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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

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    Transcript

    Download a transcript of the interview with Lee Fordham.

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  • HPH208 : Bringing down the cost of my self build – with Ben Adam-Smith

    HPH208 : Bringing down the cost of my self build – with Ben Adam-Smith

    Ben Adam-Smith looks at some of the reasons why his tender returns might have been so high. He then sits down with his wife Kay to consider possible savings.

     

    Why were our tender returns over budget?

    In episode 207 Kay and I received our tender returns and we got a shock. We had budgeted £400,000 for our house build but our returns were a lot higher!

    Before we consider how we might get back on track, I’m going to ponder reasons.

     

    The market is changing

    Over time prices will naturally go up. The market is never static. However, could there be a bigger change going on at the moment?

    The obvious culprit would be Brexit (although it’s almost impossible to verify).

    Dan Higginbotham from Parsons + Whittley specified our project, but he also specifies a number of projects that pass through their offices and he can spot trends. Dan told me: “We have seen a 12-20% increase on certain masonry projects over the last year.” He’s noticed the cost of labour has risen on their projects too (between 3-5%).

    As the design process takes a number of months, by the time the tender returns are opened the cost of the project can have risen significantly. Before we opened our returns Chris Parsons had warned us that several recent returns had come in much higher than anticipated.

     

    Costs can vary between regions

    Anyone who has tried to buy a property in London will know that it is expensive!

    If living in London is expensive, does it follow that everything else is expensive too (building contracts included)?

    Although we’re not building in London, we’re probably in the next most expensive place: the home counties. Our architecture firm, Parsons + Whittley, is based in Swaffham, Norfolk, and I believe there are differences between the regions.

     

    ‘Handmade’ or ‘bespoke’ items don’t come cheap

    On a self build you personally get to choose the quality. From the outset we budgeted £2000 per square metre, which I always think of as high end. However, it doesn’t mean you can just have anything you want (particularly when you’re designing a Passivhaus)!

    Perhaps Kay and I were guilty of getting carried away. We have specified handmade bricks for the plinth, handmade tiles for the roof and the walls are thick lime render (which requires a specialist skill).

    The interior also has recycled timber flooring, four bathrooms to kit out, and a couple of bespoke designed units.

    Knowing how much money can be sunk into kitchens, we’ve gone with fairly standard units . . . but our interior designer has helped us accessorise to make it seem more luxurious. Some of these extra fancy bits are expensive.

    Dan Higginbotham from Parsons + Whittley told me: “Normally when we’re tiling in the kitchen we might allow £25 per square metre, but the tiles you are using are £185 per square metre.”

     

    Our house got bigger during the design process

    First I must point out that this headline is slightly misleading. When we bought the plot of land, the extant consent was for a house of over twice the size of what we plan to build.

    However, when I did my initial sums with the land equation (land cost + build cost + 20-30% profit < value of the finished house) I based it on a house of 200 square metres and a specification of £2000 per square metres.

    These rough calculations were not stress tested at all. I didn’t envisage building a house of 226 square metres.

    And, I’m somewhat embarrassed that I made no allowance whatsoever for the garage (28 square metres). Although it will cost less to build than the house, we are probably still talking £1700 per square metre.

     

    We were forced to dig down to gain planning consent

    Due to the proximity of our house to the neighbours, we had to sink our home down by 0.5m in order to gain planning consent.

    This had knock-on effects. Initially we had imagined spreading the spoil across the half acre site, but the soil was poor quality and had to be taken away costing £9000.

     

    The word ‘Passivhaus’ can add expense

    If contractors haven’t tackled a Passivhaus before there is a risk factor, so perhaps they add on a little extra to take that into account.

     

    The value engineering

    Having received the cost breakdown from the contractor who put in the lowest bid (£612,234), the next part of the process was to look at every possible change to bring the cost down.

    Dan Higginbotham from Parsons + Whittley put together a spreadsheet of some ways we could to reduce cost.

    It started with the big ticket items, such as removing the garage or balcony, and came right down to much smaller items (like changing the doorbell!)

    Here’s an example.

     

    Scale down your plans to get back on track

    When severely over budget, like us, the most sensible thing would have been to reduce the floor area of the house.

    Reducing the building by 1 metre could save us £25,000!

    However, we’re not that sensible.

     

    Some savings are easy to make . . .

    Going through this list of potential savings is a peculiar exercise.

    For example, we had originally specified a resin driveway. We weren’t convinced about this at the time we made the decision, so changing it to gravel not only saved us £20,000 but probably was more in keeping with what we want.

     

    Some savings are not so easy to make . . .

    Nobody likes to go through their beautifully designed house and take out all the bits that they liked.

    A good example here might be the lime render we’d specified on the outside of the building. We could have reduced the thickness or even specified another type of render, but I think both Kay and I agreed we hadn’t come this far to compromise on things like this!

     

    There is another option to cutting costs

    Obviously not everybody will have this luxury, but we decided that paying more was the way to go.

    So we’ve come in between the £400,000 original budget and the £612,000 contract value.

     

     

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  • HPH207 : Opening our tender returns – with Ben and Kay Adam-Smith

    HPH207 : Opening our tender returns – with Ben and Kay Adam-Smith

    Chris Parsons from Parsons+ Whittley outlines a traditional procurement route. And Ben and Kay Adam-Smith receive their tender returns.

     

    Ben and Kay Adam-Smith are building a family home to Passivhaus standard and have hired architecture firm Parsons + Whittley to design this house. In episode 205, Technical Director Dan Higginbotham explained how the tender package was put together. Now five shortlisted contractors – sourced mainly through recommendation – are quoting for the work.

     

    What is a traditional procurement route?

    This is when the architect, working on behalf of the client, produces a comprehensive specification and a highly detailed package of drawings. Potential contractors then use this information to price up the job. The more detail there is, the more realistic the pricing will be (and like for like comparisons then become possible).

     

    The contractors submit only the headline figures

    For this tender process the contractors have been asked for the contract sum, how soon they could start and how long they would take to carry out the work.

    Chris has also asked for a detailed price specification, although he is aware that the contractors may not produce this (perhaps because they’ve priced it in a different way and can’t easily produce the document).

    However Chris says: “The sceptic in me thinks that by holding it back, if they get a telephone call from me today asking for their price specification, they get an early indication that they’re in the running.”

     

    A code of practice governs this process

    In order to make this fair, a procedure is laid down of how to invite and receive tenders, what must be done once they are opened and how errors might be adjusted, etc.

    On top of this, a company’s professional reputation would be at stake should any foul play go on!

     

    Everything remains confidential until the contract is awarded

    The client will generally be the one to open the envelopes (again, to see that everything is above board).

    All these numbers will be kept confidential until one contractor has been engaged.

    Only then will the figures be released, so as to give the contractors feedback on their pricing.

     

    Ben and Kay’s tender returns

    After waiting for the clock to strike midday, Kay opened the returns that had come in.

    The budget of £400,000 was quickly blown out of the water!

     

    Contractor 1 – £612,234 (39 weeks)

    Contractor 2 – £885,871 (35 weeks)

    Contractor 3 – £744,385 (35 weeks)

    Contractor 4 – withdrew due to family illness

    Contractor 5 – disqualified (submitted a day late; £664,000)

    Some contractors may drop out

    Despite working hard to make sure the contractors were a good fit and wanted to price the job, one still withdrew.

    And another had to be disqualified after it arrived late.

    Chris commented: “I’m pleased that we had a reasonable sized list, so we were not left with limited choice.”

    Next steps

    Look at Contractor 1’s pricing in more detail and explore what savings can be made through value engineering.

     

    Find out more

    Visit the website of Parsons + Whittley

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    As this podcast is somewhat behind the actual timeline, Ben is actually underway with his build!

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