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  • HPH281 : What’s it like to be an owner builder? – with Tully Gallagher

    HPH281 : What’s it like to be an owner builder? – with Tully Gallagher

    Tully Gallagher of Beartooth Passive House, explains what it was like to take a leap of faith in swapping a desk job with building a ‘forever home’ for his family.

    Interview with Tully Gallagher

    Tully had been working as an engineer in Denver for ten years when he and his family decided to move back home to Montana.

    “We went from having a very stable income, stable benefits, a pretty consistent life, to moving back home, not having jobs, living in rental houses.”

    With intentions to return and build their “forever home” for his family that would be a healthy and comfortable place to live, Tully had originally selected a builder to achieve their high performance house. When that fell through in 2017, and with the chance of finding an alternative that had even heard of Passivhaus, let alone built one, being fairly unlikely, it seemed the natural decision to take on the project themselves.

    Tully took on the house building project full-time while his wife found work at the local school to keep an income coming in.

    Passivhaus Builders’ Training gave him confidence and connections

    With his construction experience amounting to limited remodels of previous accommodation, Tully took the Passivhaus Builders’ Training in 2017. With that came access to highly knowledgeable people that he could lean on for tips and feedback during the planning phase.

    Keeping it simple was crucial

    From the outset when they decided to build the house themselves, they opted to keep the form very simple: a two-storey rectangle with engineered roof trusses.

    Emu Systems, who delivered the Passivhaus training, were trying to standardise construction methods for different climate zones and were looking for partners to pilot their system. It was a good fit with what Tully was looking for so they worked together on the construction system, building science, wall details, window installs etc.

    The remote location brought its own challenges

    Located about four miles from the town of Red Lodge (population of around 2,000), their site was relatively flat at the top of a hill in a sparsely populated area. One of the biggest problems about the location was the absence of any major DIY store; the closest being an hour and a quarter away.

    The location for the house was based on a transformer being a couple of hundred feet away so they could connect electricity without a problem.

    For waste water they had a septic system installed, and for incoming water they hired a company to drill a well. A pump runs from the well and is connected to a line that runs into the house, with a pressure tank supplying the pressure to the house and holding a reserve of the water.

    They used a pre-determined build system

    Partnering with Emu meant the construction system was already determined, which was a Passivhaus double stud wall system. Overall wall thickness is around 20 inches, incorporating mineral wool batt insulation, interior finishing and exterior siding.

    With the house being a basic rectangle shape the airtightness strategy didn’t pose any problems. The only junction that took more consideration was at the second storey floor system and how to get the air barrier out and around the floor joists.

    “But it was definitely something that we thought of early on and we picked the materials that we used for that air barrier specifically because they were really easy to work with and they were really strong and robust. They could stand up to if somebody accidentally bumped into them or something accidentally hit it and ripped it. It was pretty easy to repair and get it back to air-sealed.”

    They have moved in while finishing the interior

    Tully and his family moved into their home during November 2019. It isn’t yet finished but the pace of work has only slowed a little now that they’re in and are working on finishing the interiors. Interior doors are due to arrive soon, then it will be finishing the window trim and putting a lime plaster on all the interior walls. The bathroom installation is currently underway which Tully sees as a fairly big undertaking because of its size and his lack of experience.

    Make time to have a break

    A particularly difficult part of the build was the roof, which he saw as his nemesis and was one of the times he wished he was back at his desk job! Although not afraid of heights, he doesn’t particularly love them and with the ridge of the house being around 30 feet off the ground even getting the sheathing up there was difficult.

    He remembers one specific heart-sinking day where they had stapled all the underlayment down when it started getting very windy. Looking up from where he was having lunch at his parent’s house nearby he could see it starting to billow in the wind before a big length of it gave way and started flapping about. They ended up putting a metal roof on the house, with Tully admitting that the first couple of panels while they were figuring it out weren’t the prettiest and were put at the back of the house where they wouldn’t be seen!

    The biggest challenge Tully faced was knowing when to walk away and take a break.

    “I was wanting to get things built and it got to the point where coming out every day, I started to become a little bit more easily agitated and I just needed a break. That’s something that was a struggle for me all the way through building, knowing that I want to continue making progress so that we can move in, but at the same time I needed to take a break so that mentally and physically I could recover.”

    Take your time in the planning stages

    Tully says that although it’s been hard and taken a long time, if they hadn’t first gone through such a detailed design and planning stage it would have been a lot more difficult.

    “So, from a design phase and early implementation phase, that’s the time where it doesn’t cost you really much more money to take another month or two months to really get things lined out and understood. So, that was a big learning experience for me.”

    From a teaching perspective going forward, he would like to specialise in high performance building envelopes and the installation of that system, including the air barrier, insulation and windows. He would also like to explore the possibility of doing that in a pre-fabricated manner where the walls, floors and roof can be made into panels that can be trucked to the site and installed within a matter of days.

    It’s been a stressful but satisfying experience

    Tully’s advice to anyone taking on something similar, is to be prepared for it to take a very long time, especially if you’re doing it yourself. Spend time planning and thinking everything through as it’s a lot better to make the mistake during the planning stage than when you’re actually building it.

    Tully spent a lot of time doing 3D modelling in SketchUp, using it to model every single framing member before cutting any timber at all. He found it helped him to think through all the different junctions and how it would all work together.

    He also says to be prepared for it to cost a lot more than you are expecting.

    “So, if a budget constraint comes up and you have to choose between having really nice counter tops or spending the money to put in an additional X amount of insulation and focus on airtightness, I would say really consider that airtightness and insulation piece because you’ll probably never do that again or never have the opportunity to do that again. But you can save up for a year and upgrade your kitchen counter tops really easily.”

    “It’s stressful. I’d like to say that I’ve had way more stress in the last year-and-a-half than I had in the previous eight years probably combined. But I think I’ve also lived more and experienced more in the last year-and-a-half both in emotion and physical, actual achievement, than I had in previous years.

    I’d had an office job for the most part. I did a little bit of fieldwork. But when you go in and you’re on a computer, you can build some really cool spreadsheets or do some cool stuff in software but it’s not the same thing as being able to go to work, work hard all day, then leave and look at a forty foot long, nine foot tall wall that you built and stood up that day.”

    Find out more

    Visit the website of Beartooth Passive House

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    Transcript

    Download a transcript of the interview with Tully Gallagher.

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  • HPH279 : A beginner’s guide to building terminology – with Lee Fordham from Architype

    HPH279 : A beginner’s guide to building terminology – with Lee Fordham from Architype

    Lee Fordham from Architype simplifies some of the terminology you might come across if you’re thinking about doing a sustainable self build.

    Interview with Lee Fordham

    Shortly after qualifying as an architect in 2004, Lee spent time travelling and working for architecture practices in New Zealand and Australia. When he returned to the UK he decided to pursue his passion for sustainable design and started working at Architype, one of the UK’s leading sustainable architects, where he is now an Associate Director.

    A beginner’s guide to terminology

    For those that are just setting out in their self build journey there can be an overwhelming array of technical terminology used that can be baffling to anyone outside of the industry. Lee takes us through some of the common terms that you might come across in a sustainable self build.

    Passivhaus / Passive House

    Passivhaus (Passive House in the United States) is a building standard that was developed in Germany around 30 years ago. Using physics, the aim is to reduce the performance gap between how the building is designed to perform, and how it actually performs.

    The aim is to make the building more comfortable for the occupants and reduce how much energy the building uses, which is done with a better quality of build.

    Liz and Mike Hill’s Passivhaus – designed by Architype

    The experts will use the Passivhaus Planning Package (which you’ll hear referred to as PHPP), which essentially is a very complicated spreadsheet of data that allows them to design a building that will meet the Passivhaus criteria. The contractor will use that information to construct the building, and a certifier will guarantee the work and certify it if it meets the required standard.

    Passivhaus plaque

    MVHR

    You’ll commonly hear a Mechanical Ventilation Heat Recovery system referred to as an MVHR. They’re most likely to be used in Passivhaus buildings, but not exclusively. It is a ventilation system which extracts the used air from inside a building. It takes the heat from that air and mixes it with fresh air which is being brought into the building from outside, to provide every room with fresh, pre-warmed air.

    The air is filtered coming into the building, and different filters can be used according to whatever is in the external air in that area.

    A key benefit over natural ventilation is the element of control over any given space, ie removing moisture from bathrooms etc.

    An MVHR for a domestic dwelling is roughly the size of a combi-boiler and will need to be incorporated into the building’s design.

    MVHR unit at Landsdowne Drive Passivhaus – Green Building Store

    Foundations / Footings

    These will usually be designed by a structural engineer and are what sit under the building to evenly transfer the weight of the building to the earth. The type you use might be dependent on what your ground conditions are like, but some examples are pile foundations, deep strip foundations and raft foundations.

    U-value

    A complicated one to explain, but essentially it’s a way of measuring how thermally conductive a component or a series of components (like a piece of glass, wall or roof) is. It is the rate at which heat travels through. The lower the U-value, the better it is.

    The aim is to have fairly consistent U-values across all the components in a building. Having just one element that isn’t consistent could act as a magnet for moisture and potentially damage the structure. This can partly be achieved by better insulation, triple-glazed windows etc.

    The U-values form part of the data that feeds into the PHPP system.

    Airtightness

    At a very basic level, this is about eliminating drafts in a building. It’s relatively easy to achieve but needs to be thought about at the design stage. At Architype they denote the airtightness layer on their detailed drawings using a red line, which shows the contractors where to take particular care in the construction so as not to damage it.

    To meet building regulations, when the building is finished an air test will be carried out. The building has a giant fan attached to it and is either positively pressured, ie blowing air in, or negatively pressured, ie extracting air. The rate at which the air leaks gives you your air test result. It is a measure in pascals of the pressure of an internal area. Building regs require you to get a result of 10 or less.

    The method in a Passivhaus building is slightly different. This takes an average reading from the building being both positively and negatively pressured, to give an n50 value which is how many volumes of air changes there are in an hour. The Passivhaus requirement is that it should be less than 0.6, so significantly better than building regulations.

    Build system / construction method

    This is a way of describing what method you are going to use to construct your building. Examples include timber frame, masonry, brick and block, insulated concrete formwork (ICF), pre-cast concrete, in-situ concrete, and cross-laminated timber.

    Pre-fabrication

    Pre-fabrication is where components, or indeed whole buildings, are made off-site. This could be from wall panels, to timber frames, to bathrooms that are fully plumbed and tiled, to entire houses.

    MAKAR production facility

    You can even go to the factories and choose your handles, paint finishes, floor finishes etc. When they reach the site they are connected together. The advantages of building the elements off-site is it can be quicker, they’re not subject to delays or damage from the weather, and often it can result in better quality and working better when brought to site.

    Huf Haus

    Zero carbon

    Lee says that this is a difficult one to explain as there are many different interpretations of what it means.

    Generally it refers to off-setting the energy use in a building. So the better your building is, ie a Passivhaus, the less carbon you have to off-set because you’re not using as much energy.

    Looking deeper into it, some people will be referring to zero carbon in use, which is the energy that is used starting from the point of when it’s been built, through to its end of life.

    But there’s also embodied or sequestered carbon, which takes into account everything to do with the design and construction of the building, together with the in-use energy and sometimes through to the demolition. This is more complicated to account for, although there are tools which can help explain for instance, how much energy is used in getting a tree from Germany to the UK to use in a timber frame.

    Custom build

    Whereas self build has many decisions for you to make, whether or not you’re doing it in the purest sense of building it yourself, or whether you’re commissioning someone to carry that out for you, custom build can take some of those decisions away from you. There will be an offering from the custom build company, but with options for you to customise it. That could be in terms of the style of the house, the layout or the finishes. It might not be as individual as you would get with a self build, but it can take away a lot of the headaches!

    Potton Homes design

    Solar shading / brise soleil

    Effectively the same thing, brise soleil or solar shading would be used on the south facing side of a building to limit the sun coming in during the summer months when you don’t want the building to overheat, but allowing it to come in during the winter when the heat is required. Generally it would be a horizontal component that sits over the south facing glazing, whether that be a roof overhang, external canopy or series of louvres.

    External louvres – Charlie Luxton Design
    Wimbish Passivhaus Scheme – Parsons & Whittley
    Ditchingham Passivhaus Scheme – Parsons & Whittley

    On an east or west elevation you would usually have a vertical component, and that’s just to do with the angle of the sun at certain times of day and certain times of year. Windows on the east and west elevation can be harder for dealing with glare and overheating issues.

    Lee says the ideal situation is to have the building facing south where the solar gains can be controlled more easily.

    Design team

    The core members of a design team are likely to include: an architect, structural engineer, civil engineer, mechanical and electrical (M&E) engineer, and possibly a project manager.

    Beyond that, depending on your site and your level of involvement and interests, you might also have: landscape architect, ecologist, arboriculturist, quantity surveyor, Passivhaus designer etc.

    Renewables

    Renewables refers to technology that generates energy. This could be photovoltaics, wind turbines, hydro power etc.

    Air source and ground source heat pumps

    An air source heat pump takes energy from the temperature in the air. Any air above zero degrees has energy in it and this can be taken and transferred into heat or hot water for your house. Similar in size to a washing machine, they’re put on the outside of a building.

    The ground source heat pump works in much the same way but will take the energy from the ground. They have pipes which can either be spread horizontally in the ground which will require a lot of space, or as a vertical spread of pipes, which need less space but are a lot more expensive.

    Plans, elevations, sections and details

    These are examples of the different types of design drawings, created by Parsons and Whittley for Ben Adam-Smith’s house:

    Plan – This is an aerial view, looking down onto the building. You can have different plans to show each floor of the building, but they can show the roof, doors, walls and windows, together with the internal layout.

    Elevation – An elevation is a drawing of what the outsides of the building look like from where you’re standing. A south elevation for example would be the side of the building that is facing towards the south.

    Section – This is like slicing down through a building to show what’s inside. It will show the components of the walls, floors, roof etc.

    Details – By taking a section drawing and zooming in you will create a detail. They can be various scales, such as 1:2 or 1:10, and are an in-depth analysis and instruction for the contractor showing how to construct that part of the building. It would show them where the airtightness line is, where the insulation is, and how wide cavities would need to be.

    Soft landings and performance monitoring

    A soft landing is about making sure that once the building has been constructed, that the operator of that building knows how to use it. Obviously if you’ve built it yourself then this wouldn’t be necessary, but if you’ve largely commissioned other people to complete the project then you should have someone tell you how it all works.

    Performance monitoring can take place throughout the build process but in particular Lee refers to monitoring once the building is complete. This uses sensors to check on things like the internal temperature, humidity and CO2 levels, to make sure the building is performing as it was designed to do.

    Tender

    The way you tender will depend on what kind of contract you will have, but essentially a tender is a set of information that is put out to someone for a response. They will price up the aspects on the tender and return it with their figure and requested documentation. It can be a tender for a design team or for a contractor. The returned tender documents are then scored and weighted according to whatever your priorities might be. For some that might be 80% of the marks will be based on how competitive the price is, but for others they might weight it more heavily in favour of quality and not necessarily who is the cheapest.

    A key thing is to make sure the information and drawings you are sending out are as comprehensive as possible. That way it can be priced accurately for what you will be needing. Without that detail they will be adding an element of price risk to their response which will invariably make it much more expensive.

    Window parts

    • Sill – The ledge at the bottom of the frame.
    • Head – The top of a window where it meets the wall. It can be internal or external.
    • Jamb – The side of the window
    • Reveal – The part next to the jamb. Can be internal (usually plasterboard) or external (usually timber or brick). If the reveals are set very deep into the thickness of a wall they can provide some shading to the window
    • Mullions and transoms – Found on traditional Victorian style windows, the mullions are the vertical bar in the middle of the window, and the transoms are the horizontal bar.

    Roof parts

    • Trusses – The pieces, usually made of wood, that actually make the roof structure
    • Joists – A horizontal structural element that supports the floor and/or ceiling
    • Eaves – The part of the roof that overhangs the wall. Usually if it’s a sloping roof it would be the part which overhangs the gutter
    • Soffits – Underneath the eaves, the soffits are the horizontal section that you can see
    • Ridge – The point right at the top of the roof, usually where two pitches come together
    • Verge – The part at the side of the house. Usually there would be a bargeboard or piece of wood that goes down the side
    • Parapet – Usually a piece of wall that protrudes up above a flat roof
    Roof trusses
    Roof joists

    Find out more

    Visit the website of Architype

    Follow Architype on Twitter

    Transcript

    Download a transcript of the interview with Lee Fordham.

    The Hub

    If you’re new to self build and looking for more information, then be sure to check out The Hub. It’s full of great resources, video diaries and support from a community of like-minded self-builders.

    Please connect with me

    Subscribe, rate and review the podcast in iTunes

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  • HPH278 : A beginner’s guide to self build – with Geoff Stow

    HPH278 : A beginner’s guide to self build – with Geoff Stow

    Having worked on his own hands-on group self build project, and site managed others, Geoff Stow shares his experience on where to start when it comes to self build.

    Interview with Geoff Stow

    Geoff’s involvement with self build started years ago when he worked with a community arts project in south London, making a video with a group of self builders who were promoting their scheme in Lewisham. So when Lewisham decided to do another scheme he put his name down, chairing and being part of a group of 13 that built their own houses on a Walter Segal project. From there, his involvement continued with working as a site manager for other group self build schemes, including the Hedgehog project in Brighton.

    “My background isn’t as a builder really but I think in some ways that’s quite interesting because it’s actually coming at it as a novice. I’m sympathetic with people who are trying to get a scheme off the ground.”

    Geoff also runs courses on timber frame self build, and self build project management at the Centre for Alternative Technology in Wales.

    Hope Wharf
    Hope Wharf

    It’s likely to be harder than you’re expecting!

    Geoff says he’s never met anyone who said they wished they hadn’t done it, but does stress that you should be prepared for a lot of hard work. He thinks there is actually very little in place to make things easier, with the majority of things at the beginning like planning and finding out how to connect services, being geared up to failing.

    Whereas most people spend their time at the beginning sketching designs for a plot they don’t yet have, he recommends instead taking that time to research and understand the issues involved. That could be around planning, environmental issues, insulation, ventilation etc.

    Take the opportunity to go to the exhibitions to grow your understanding and help you talk the same language as the experts, but bear in mind that a lot of it is sales focused.

    Understand the issues around claiming back the VAT, and get yourself organised with a good accounting system so you can keep track of staying within budget.

    Build your knowledge by checking out some of the self-build books around, like Mark Brinkley’s Homebuilder’s Bible. They’re worth reading for finding out about things like health and safety requirements, working out how you’re going to organise your project, whether you might be able to site manage it yourself, and understanding what the relevant issues around that might be.

    Use your suppliers by asking for detailed information, and if they can’t provide it then don’t use them. Geoff gives the example of a window supplier, where you should be providing wall designs and asking what’s the best way of fitting them.

    Have a sensible budget

    Keep in mind that things rarely come in under budget or ahead of schedule, so have a sensible budget that is based on real costings, not just how much you’d like to spend or how much other people have spent. Be wary of the figures that people quote when they say their house cost X amount per square metre, as you never quite know what has been included and what has been omitted.

    Budget high for all of the initial stages. Things like the foundations, services and access roads can have plenty of unknowns and it’s much easier to price up more accurately for the above ground works. Add on a good contingency once you get quotes in as this should free up money later on.

    In addition to budgeting for the overall cost of the build, if you’re using a self build mortgage you will need to consider your cash flow. They work by releasing money once a stage is finished, so although you might have enough money in total, you might find the project grinding to a halt if you do not have it available at the right times.

    Finding land will probably mean making compromises

    Geoff’s key piece of advice for finding land is to be flexible, as there’s not that much of it around. He thinks it best to spend time in the area where you’re looking as quite often word of mouth can be helpful.

    Take the time to understand your site

    Geoff estimates that, depending on your skill base and level of organisation, around a year is a good length of time to spend on your research. As part of this he recommends spending time on your site and understanding how to place the house so you can get the best out of it. This will include things like orientation, window placement and learning how the sun falls on the site at different times. During this period you can also be going to exhibitions and talks, doing courses, going on Passivhaus open days and speaking to other people that have built their own homes.

    Focus on getting the fabric of the building right

    Geoff says you’re never likely to hear someone say that they wish they’d put in cheaper windows or used less insulation! So concentrate on getting the insulation, windows, detailing of doors, heating systems etc right, and getting it to the best quality that you can afford. It doesn’t necessarily have to be the perfect house straight away, and you can always retrofit your dream kitchen or build a second stage later when finances allow.

    Speak to other people for advice

    Get as much information as you can from suppliers and manufacturers about their products and their detailing. Also speak to builders’ merchants who might be able to suggest alternative products that you might not have come across.

    Geoff follows a couple of Facebook groups which he says, if you filter through a lot of the rubbish and sales pitches, can actually have really good information and experience that people are willing to share.

    “There’s no right way of doing it…what there are is a lot of wrong ways!”

    Geoff stresses that there is no right build system to use, and the method that you choose will be based on a lot of criteria. Whatever method you do choose, just make sure that it’s of the highest quality you can afford.

    A lot of it will be down to personal preference, and whether you like timber, stone, brick etc.

    Geoff’s preference is for timber frame, partly for the accuracy and speed which it affords. He personally would also avoid very innovative systems by very small companies as there can be a question of whether or not they can actually deliver.

    Also consider what kind of products you want to be using. Some people might want high performance foam insulation, whereas others will want to go as natural as possible and use sheep’s wool or Warmcel type insulation.

    “Whatever building method you go with, you just need to really understand what the issues and the criteria are. The good points and the bad points. And ignore what people say about their method being the best, it’s modern or it’s developed by NASA or something ridiculous. Just understand what the issues are with all of them and base it on real costs.”

    Decide how much involvement you’re going to have

    As a client there are options as to how involved you will be on the project, ranging from paying huge sums of money to a building company who will do everything for you, to getting hands-on and doing practically everything yourself.

    Probably the biggest deciding factor is thinking about what skills you have, but not necessarily assuming that because you can do something yourself it will necessarily be quicker or cheaper.

    “So, if a job that a skilled person can do quickly and well and you can do fairly well and take a long time over, that might mean that it’s longer before you move in and you’ve got more mortgage repayments, more insurance, if you’re renting a house then there’s the rent that you’re paying while you’re doing it. So, you might think you’re saving some money but actually, are you really?”

    You might also find that by doing a job yourself and taking longer about it, you might be holding up the next trade that can’t come in and do their job until you’ve finished. Instead there might be jobs that you can do which won’t involve holding anyone else up, like prepping and putting up cladding for example.

    When it comes to managing the project, you have the choice of paying someone else to do it, or doing it yourself. Obviously doing it yourself in theory should save you money, if done well, but consider whether you have the expertise to: keep things on track and on budget, get prices and employ subcontractors, nudge people when needed, make sure the work is being done to a high standard, check health and safety standards are being adhered to, keep neighbours on side etc.

    Do it on the terms of what you can afford, what skills you have and what you want your level of involvement to be.

    Being too fixated can be a common pitfall

    Geoff sees people that might become completely fixated on building a straw house for example, when actually the site they have might not actually be ideally suited.

    “It’s just understanding the issues around those sorts of things and not necessarily getting very fixated on one thing where you end up making your build really complicated because you’ve got this one fixed idea that you saw somewhere on television that you want.”

    He also says that no matter what you do there will be people saying that you shouldn’t have done it that way. And maybe even you yourself will look back and think you might have done it differently, but just try to get as much right as you can based on the knowledge and research at the time.

    People always say they want to be in by Christmas!

    Geoff suggests when it comes to how long a project will take, that if you’re planning to do a lot of the work yourself then try and avoid it going over two winters, as the second is always particularly tough (especially so if you’re living in a caravan!) Realistically you could be looking at 12 to 18 months on site, but less than that if you have builders.

    He also recommends trying to get as much finished as possible before moving in, even if that means throwing money at some good contractors to speed things up. Finishing off works once you’re living there is much harder to do and becomes less likely to ever get done.

    To help keep on track with the budget and schedule, try not to make changes as you go along. You can make minor changes but you don’t want to be deciding to change window placement or move walls once work is on site.

    Work with an architect who is on your wavelength

    Keep a scrapbook of ideas and images that you like and can show to a designer or architect, and make sure you work with someone who is going to design the sort of thing you want.

    Although it’s not necessary to employ an architect, having a good one on board that is sympathetic to your ideas can elevate your plans and give you a wow factor, rather than simply being a series of rooms joined by a corridor.

    Having an architect involved could just be paying someone for a simple check over your plans and offering advice, to a full package of designing the house, getting it through planning and building control, and seeing the whole project through to completion and sign-off at the end.

    A key consideration in choosing who to work with is finding someone who is on your wavelength that you feel you can work with. Ask for proof that they really understand the issues that matter to you, as some might claim to be providing a sustainable and energy efficient building just because it complies with current building regulations.

    Participants on a timber frame course

    Find out more

    Visit the website of the Centre for Alternative Technology

    Join House Planning Help’s Facebook group

    Transcript

    Download a transcript of the interview with Geoff Stow.

    Please connect with me

    Subscribe, rate and review the podcast in iTunes

    Rate and review the podcast on Stitcher

    Like our Facebook page

    Follow us on Twitter

  • HPH252 : How to reduce the embodied carbon of your new home – with Chris Magwood

    HPH252 : How to reduce the embodied carbon of your new home – with Chris Magwood

    Chris Magwood, a director at the Endeavour Centre in Canada, explains the importance of embodied carbon and how building with plant-based materials could transform our new homes into carbon sinks.

    Interview with Chris Magwood

    Chris Magwood has been working in sustainable building for the last 25 years. He’s also written several books such as Essential Sustainable Home Design, Essential Prefab Straw Bale Construction and Essential Hempcrete Construction.

    For the last 8 years he’s been teaching at the Endeavour Centre which is a sustainable building school based in Peterborough, Ontario.

    What is embodied carbon?

    Embodied carbon is the total carbon emissions associated with materials through initial harvesting of raw materials and through the entire transportation to manufacturing facility and everything that happens in that manufacturing facility. And then transportation to a job site and the associated emissions with actually doing the installation work on the job site.

    Carbon dioxide is an expression of all greenhouse gases

    As carbon dioxide is not the only greenhouse gas, other emissions are translated into a carbon dioxide equivalent.

    Chris says: “The expression that we use in the calculations is CO2-E – so, carbon dioxide equivalent. So, if it’s carbon dioxide, one molecule equals one. But if it’s methane, one molecule would equal twenty-five or whatever the number happens to be.”

    Energy isn’t necessarily a proxy for carbon

    For a long time the term that was being used was embodied energy, but it’s important to realise that energy isn’t necessarily a proxy for carbon.

    So, two factories could use the same amount of energy, but if one is all solar and one is all coal powered, then the emissions profile of the two would be very different.

    Even though in embodied energy terms, that number might look the same. So, this is specifically trying to make emissions the focus and not just energy use.

    The carbon footprint of building materials vary drastically

    While we probably understand that different building materials have different carbon footprints, when Chris crunched the numbers he was surprised by the extremes.

    Chris comments: “I was pretty stunned at the results in that some things just had such a huge carbon footprint and I had never really considered that impact being so big before. And then some things were miniscule.”

    Plant based materials give us the opportunity to turn our buildings into carbon sinks

    As plants grow they pull CO2 out of the atmosphere and release oxygen. Effectively they put the carbon into their physical structure.

    So if you’re building with a material that has atmosphere carbon stored in it – basically any plant material – in terms of the calculations, it’s a negative emission. In other words there’s a drawdown of carbon rather than an emission.

    “Building with a lot more plant material, we could not only reduce that carbon footprint to zero, we could actually take it into the negative numbers and make drawdown buildings that are in their way drawing down climate change rather than contributing to it.”

    Straw is one of the best materials

    Chris compares two plant-based materials as an example of how even a little processing can increase the embodied carbon.

    Although cork requires quite a bit of heat in its manufacture, it still ends up being a net store of carbon.

    Straw, however, has almost no emissions in terms of the harvesting and manufacturing. It’s also the waste product of an annually renewable crop. And in the case of grain straws, the carbon in the stalks would have just returned back to the atmosphere in fairly short order.

    Chris adds: “Even though all of these plants more or less store a similar amount of carbon, the amount of processing energy that’s gone into them does change the net profile.”

    Endeavour class at a straw bale raising
    Six carbon storing insulation materials

    Timber has a more complex picture

    It’s much harder to attribute carbon storage to timber because the carbon that’s in that tree, depending on when the tree was cut, that tree could have gone on drawing down more carbon as a living tree than it does as a stored tree.

    And if you only end up using about half the volume of the tree to make a timber product and the rest of the carbon from that tree ends up back in the atmosphere, you haven’t net stored any carbon. And if you’ve released a whole bunch of carbon from the soil of the forest floor, then it may be worse than a draw down. It might actually cause emissions.

    We could become more intentional about what our buildings are doing

    Chris is not advocating that all buildings need to be entirely plant based, but he does see a massive opportunity to be more intentional.

    “If you can weigh up the carbon storing materials with the carbon emitting materials, you can actually plan a building to land on a target that you’re aiming for, whether that’s carbon neutrality, storage or a slight number of emissions.”

    Environmental product declarations report the environmental profile of a material

    In carrying out this research, Chris used environmental product declarations, an ISO standardised way of reporting on the environmental profile of a material.

    This is third party document where the third party goes in and looks at a manufacturer and traces the entire chain of that product and essentially does a calculation to look at its global warming potential from harvesting of the raw materials through the entire manufacturing process.

    Chris explains how he used this information: “I’m basically using those numbers to then multiple it out on my own buildings. So, if a particular environmental product declaration says there are two kilograms of CO2-E per kilogram of this material, then I figure out how many kilograms of that material are in my building and then I can multiply that out and do that for all of the materials and then total that up and get a net, whether it’s a net emissions or a net storage.”

    Concrete, glass, foam and steel all have high carbon footprints

    Perhaps as one might expect concrete, glass, foam, and steel all have significant carbon footprints associated with them.

    Building a Passivhaus will not necessarily have any impact on embodied carbon

    If you’re building a Passivhaus, then your choice of materials is really important.

    “The way a lot of people will achieve Passivhaus standard here in Ontario, Canada, is they’ll throw a whole bunch of foam insulation at that building. And when I modelled that, the embodied carbon footprint, the upfront emissions of making that building, don’t ever get paid back by the energy reductions. So, if somebody was using that strategy because they thought they were doing something for climate change, they’ve actually done exactly the opposite.

    The carbon profile of the grid varies according to where you live

    This goes back to energy not necessarily being a proxy for carbon.

    Energy efficiency – in terms of carbon emissions – is only useful if you use dirty energy (with a high carbon content).

    “Here in Ontario, we shut down our coal plants a few years ago, and so our electrical grid is relatively carbon free. And so, savings in energy efficiency, especially moderate ones, our code is now pretty good in terms of baseline energy efficiency. Going from that to Passivhaus, while it may have good implications for the owner in terms of lower bills and comfort and all that kind of stuff, from a carbon emissions profile, it’s almost meaningless with the difference between a code built house here in Ontario and a Passivhaus in terms of the emissions profile of operating that building, it’s negligible because the carbon profile is so clean on the grid.”

    Canada’s Greenest Home

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  • HPH233 : How to choose a construction system for a house build – with Mike Hardwick

    HPH233 : How to choose a construction system for a house build – with Mike Hardwick

    Self build consultant, Mike Hardwick, explains the pros and cons of different construction systems.

    Interview with Mike Hardwick

    Mike hasn’t followed a typical path into the industry. He actually worked in the RAF for 26 years, and with all the different postings came many different house moves for him and his family. Deciding to settle in one place they selected a location (based in the middle of where possible future postings could potentially be), bought a plot of land and built their own home.

    Mike often found himself propping up the bar in the Officers’ Mess answering questions about how to build your own home. When he came out of the Services in 2005, he realised that what he would really like to do was get more people interested in building their own homes, and at that point decided to make a business from it.

    The first series of Grand Designs – copyright Channel 4

    Mike’s house build coincided with the first series of Grand Designs

    They bought the land for their self build in 1999, got planning permission in 2000 and in 2002 were able to move in. Doing the build in parallel with the first episodes of Grand Designs often left them able to empathise with the self-builders, pick up a few tips or wonder why they were doing things a certain way.

    Mike credits Grand Designs for redefining the scope of self build, making people realise that it doesn’t have to just be for the very wealthy. Although he does concede that the TV programme “Sensible Couple with Reasonable Budget Build Modest House On-time and On-budget with a Competent Builder” is never going to get commissioned!

    A build system is the structural element of the house

    That is, what it is built from and held up by. “And the confusing bit with a build system is that just because what’s on the outside of a house looks like maybe a brick, it doesn’t necessarily mean that it’s a house made out of bricks structurally.” Most, but not all, houses in the UK are built with a twin-leaf construction, where the inner leaf does the supporting work and the outer leaf makes it look pretty, with timber, brick, tiles etc.

    As well as holding up the structure of the house and being the main material used in the construction, it is what the services run through and are bolted to.

    As such, getting the right system for you is going to be an important decision to make, and generally it’s entirely your choice. Because the building system you use doesn’t usually dictate the external appearance, the planners aren’t interested. So as long as Building Control are happy that it will comply with regulations then you are free to choose.

    Price comparisons aren’t straight forward

    Mike explains that people will always ask him which system is the most cost effective, but drawing a price comparison is actually quite difficult. He does say that there is a fairly narrow band of cost when it comes to the different build systems, and what influences the price most is actually the detailing and the finishes that go on inside.

    What really hikes the price is when you trade in the materials for speed of construction, such as with houses that are pre-fabricated and then erected on site in a matter of days.

    Masonry construction

    Mortgage companies for example will typically ask whether the house you’re buying is of masonry construction with a tiled roof. They like it because it has substance to it, it’s a safe thing to invest against, and will be appealing to potential future purchasers.

    “It’s the way that we’ve trained our builders, it’s the way we’ve been conditioned to think about how houses work, and it’s what we fall back to. So, they’re easier to insure, they’re easier to mortgage against and they’re easier to sell. Which is why people still do it.”

    If you’re working to a modest budget, then using brick and block is generally at the lower end of the cost spectrum, so is likely to be a baseline for constructing your own home. They are quick and easy to build, relatively cheap to buy, and are easy to handle and cut up. They tick the boxes for mortgage companies, insurers and builders.

    Other positives are the strength they provide, that you can put beam and block floors in. The thermal mass provides a stable temperature throughout the house, and the masonry affords you flexibility of design. You can build just about anything you want in masonry, and combined with steels can give you large, open spans.

    Traditional breeze blocks were made out of cement covered cinder. Modern blocks are lightweight and made from pulverised fuel ash, so the detritus from a coal-fired power station mixed with resin and turned into a block. The aerated middle traps air and provides insulation, and also makes them lighter.  In the UK there is currently a shortage as there aren’t many coal-fired power stations remaining, so the raw materials have to be imported.

    Timber frame

    Timber frame basically replaces that breeze block element with a structural framework of timber. It is associated with being environmentally friendly, high quality, accurate off-site manufacture. It is efficient, effective and with the speed of construction it makes for an attractive proposition.

    Whereas masonry has high embodied carbon in the manufacture, timber frame is carbon neutral in that you plant a tree, chop it down and plant another tree. Timber is also a flexible material in that you can build the walls, ceilings, floors, windows, doors, stairs etc from it.

    Mike is keen to point out to people who worry that building a timber frame system might suffer from problems such as termites or rot, that probably around 65% of what we would call a masonry house is actually made from timber anyway, being the roof trusses, stairs, skirtings and so on.

    Mike concedes that, if pressed, he would say timber frame is probably the cheapest way of building the structure of the house. But that would only be if you were doing the most economical and basic timber frame with no frills, and without doing anything to attenuate the acoustics. Most self-builders would want to go above and beyond building regulations and put in good sound-deadening insulation to minimise noise transmitting through the house. When taking into account the extra money on the sound-proofing, you are probably then looking at a more expensive path than masonry.

    “Now, if you want the environmental stuff but you don’t want a lot of noise transmission, timber frame with noise attenuation is a good thing but it’s going to cost you more than it will for a masonry house straight out of the box. This is where you need to start doing your homework and making your calculations about what you actually want, how you’re going to live your life, and what you’re trying to get from the home that you’re building.”

    The thing to remember with timber frame is that it will last well as long as the moisture content in the structure is kept to a minimum, and allowed to escape so that it doesn’t build up. On the inside of the house behind the plasterboard there will be a non-breathable, vapour control layer. This stops any moisture occurring inside the property from getting into the structure. On the external wall, underneath the render or brickwork, is a breathable membrane, allowing any moisture that does get inside to find a way out.

    Insulated Concrete Formwork (ICF)

    These are a type of fire retardant polystyrene foam block. They fit together to create a solid outer wall and a solid inner wall, with the gap in the middle being filled with poured concrete. When the concrete sets and cures, you end up with a waterproof, insulated, monolithic wall which is highly insulated, highly airtight and with the strength and density of a masonry wall. This makes it popular for people building to the Passivhaus standard.

    It also benefits from being very quick to construct, you don’t need to be too skilled to put it together, and being waterproof is a good choice for flood-prone areas.

    Some people aren’t keen on this method because of the perceived embodied carbon being quite high. In reality, Mike says, they are mostly made of air with very little actual structure to them. There are other alternatives, such as Durisol blocks which are much the same in principle but use chopped up timber instead of the polystyrene foam as the insulant.

    Although there is a lot of concrete used, Mike suggests thinking about the amount of energy that the structure saves straight away with its high levels of airtightness and thermal performance.

    It is worth thinking about future use, as putting in more doors or windows for example at a later date is going to be very difficult. Also perhaps a marine ply or a Thermacell type board is advisable for indoors when there might be considerable weight such as cupboards or TVs to be hung from them.

    Structurally Insulated Panels (SIPs)

    These are manufactured off-site and built of two oriented strand board (OSB) sheets that are filled with expanded urethane insulation foam. The panels can be cut, shaped and fixed to other panels to make a complete housing structure. They tend to be accurate, airtight, watertight and put up on site very quickly.

    If you were thinking of using this building method, you would take your designs to a SIPs company whose CAD systems would create the plans to feed into the machines that produce the panels to millimetre perfection. These panels work with the other panels around them, and can even have steelwork in there for covering large spans, to give the structural integrity to the house.

    Mike explains how the success of a masonry constructed home is very dependent on the quality and skill of the bricklayer. With ICF it’s harder to go wrong, as the panels are designed to fit together at 90 degrees, meaning the walls are going to be straight and it will be easier for fitting out afterwards.

    One drawback is that you can’t later decide to move things about or add doors or windows because the structural integrity will be compromised.

    “The advice I would give to anyone contemplating building in SIPs is to spend a really long time thinking about what you want and what’s going to go into your house, and the design of your house, and then say, ‘that’s it, no more changes. We’re happy with this. Go and provide this house.’ Because once it goes into the computer and they pull the handle, then that’s what you’re going to get. If you suddenly say, ‘about that wall there, can we have another one here or another window here? Can we have that door moved to the left?’ that’s going to be expensive, it’s time consuming, you’ve got to start again and recalculate the whole thing in the worst cases.”

    In terms of cost, Mike says ICF and SIPs used to have roughly a 10% premium on them because there were new factories to be paid for, but as they are becoming more common-place the prices are more competitive. Some manufacturers are even assuring that they can produce a house for about the same cost as brick and block.

    Straw bale

    Previously seen as something you wouldn’t consider for mainstream building, nowadays the increased focus on energy efficiency, natural materials and environmentally conscious building has given straw a greater appeal. Mike explains that structural straw bales, as opposed to ones you would buy direct from a farmer, are processed and compacted to form dense blocks.

    “When you encapsulate this within a lime water and plaster that you would normally be using with this build, you’ve got something which has got no oxygen. So, it doesn’t catch fire. It doesn’t. It’s just a really good carbon neutral method, environmentally friendly way of getting all that insulated wall which looks really good as well.”

    Straw bales do mean that you end up with thick walls, but for some people that is a positive feature. The deep window and door reveals combined with the lime plaster make it look and feel like a solid house with a natural, rustic feel.

    Mike concedes that some mainstream lenders and insurance companies might not be keen to deal with these, but others like the Ecology Building Society see the benefits and will lend against them.

    Prefabricated system builds

    Most of these factories tend to be in continental Europe where the prefabricated kit is made and then brought to your plot to be assembled. This method probably won’t suit those on a smaller budget but for projects on a grander scale, or at least a grander budget, they will be rewarded with superb, quality finishes.

    “And for those people who want to be hands-off with the self-build rather than actually getting involved and really worrying about how the bricks go and how the timber frame is constructed, they can sit back and basically say, ‘here’s the house I want. Build me one of those. Here’s where I want it.’ And somebody else goes and does it for you. You pay for the privilege of doing that, but the stress levels are going to be a lot lower than somebody who’s actually project managing their own build all the way through.”

    Again, this is a system where decisions need to be made up front as any changes later are going to be extremely costly.

    Steel frame

    A steel frame self build house wouldn’t be commonplace in the UK. They tend to be more popular in warmer climates. If you have a steel structured house and are trying to stop cold-bridging then you’re starting from a losing position.

    However, recent changes in planning regulations, where permitted development allows people to take farm buildings and convert them into residential dwellings with less of the hassle, has made extensions and renovations of steel-framed farm buildings more common.

    Thin joint

    The masonry industry has recognised some of the problems of building with blocks (weather dependent, speed of construction, reliant on quality of the builder) and come up with a variation on the masonry theme called Thin Join. They use over-size versions of the cinder blocks and instead of using a 10mm sand and cement mortar base, they are held together with a type of glue adhesive.

    “But by taking out things like the mortar bed, you’re taking out two things. One is a passage for air to get through, and when air can get through, noise can get through. So, by taking that mortar bed out, you’re putting better airtightness into it, putting more insulation into the wall and you’re taking away some of the need for skilled construction to put it together”.

    It’s also a cleaner system, using a bucket of adhesive instead of having piles of sand and cement spreading around the site.

    Which system to use depends on what is right for your circumstances

    “So, if low cost is your priority then you need to be looking at the traditional masonry or the timber frame setup. If you’ve got family and you want a bit of peace and quiet, you want some separation of noise, acoustic attenuation, then the masonry end is probably the way you want to be looking at.

    If you want energy efficient, you’re environmentally aware, then you want high efficiency and low running costs. Then timber frame is probably where I’d be looking at. That’s at the lower end of the spectrum on there.

    And as you go up the performance scale, that’s when I’d start looking at the ICFs and the SIPs panels. They might cost you a little bit more to build but again, there’s a trade-off there against the cost of the materials and you need less labour to put it all together.

    At the very top end, if you really are a hands-off builder and you want the sort of quality which just comes with that continental standard, then these system builds that we spoke about, hand over the money and let these guys come and build it. You’ll have a house which will be good enough to feature in the magazines. But you will pay for that privilege.”

    Additional resources

    Build It Magazine

    NaCSBA

    National Self Build & Renovation Centre

    Transcript

    Download a transcript of the interview with Mike Hardwick.

    Please connect with me