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Tag: Insulated Concrete Formwork

  • HPH284 : Build It magazine’s Self Build Education House – with Calum Taylor and Opinder Liddar

    HPH284 : Build It magazine’s Self Build Education House – with Calum Taylor and Opinder Liddar

    Calum Taylor and Opinder Liddar talk through the design and construction of the ‘Self Build Education House’ at Graven Hill.

    Interview with Calum Taylor and Opinder Liddar

    Calum Taylor is the owner of Build It Magazine, the longest running self build magazine in the UK. Together with their website and exhibitions, their aim is to provide expert advice and information in a practical and down to earth manner, to help self builders make the difficult decisions as easy as possible.

    Calum has been working on Build It’s Self Build Education House at Graven Hill with Opinder Liddar. Opinder is a director of lapd Architects. They are based in Oxfordshire and specialise in residential projects, particularly for self builders.

    It is a showcase of possibilities

    Coinciding with Build It magazine’s 30th anniversary, Calum’s idea for the Self Build Education House was to showcase the possibilities available to self builders by demonstrating the processes and some of the products that can be involved in a self build journey, whether or not they themselves were building at Graven Hill.

    It would also be a great experience for Chris Bates, the magazine’s editor, to have hands-on involvement with the project management.

    The house has been built on the Graven Hill development

    Graven Hill is a ground-breaking development: the first of its kind in the UK. The land was formerly owned by the Ministry of Defence before being sold to Cherwell District Council to develop. The site has planning permission for 1800 new homes, up to half of which are designated for self build.

    Calum says it has its fair share of cynics however, who question the plot sizes as being more like developer plots.

    “But I think it’s incredibly important that for self-build to really become the norm in the UK as opposed to what is done by a relatively few, relatively wealthy people, that we need to look at different models and we need to look at how you can have fantastic housing on smaller plots of land. And if you can do that with the profit on the land going back into the local community via the council then that strikes me as being a perfect model.”

    The plot passport outlines the parameters

    A number of plots had been allocated for show home use and, following a tender process, Calum successfully won a corner plot around the back of the houses featured on Grand Designs: The Street.

    Each plot comes with its own “plot passport” which defines certain parameters, such as maximum height and the footprint of where the house needs to be. With those established, the design can begin to develop as a response to the site aspects.

    It needs to work as a showcase, and a home

    In five years’ time the function will change from show house to a home that will be lived in, and this consideration formed part of the brief. It needs to have enough space for people to walk around in, while still feeling like a home.

    “Primarily we want people to look at it as ‘I want to live here. This is an amazing house.’ We don’t want them to think, ‘this works very well as a museum.’”

    With a plot restriction of 160m², the design was put in for planning at a size of 150m². The Graven Hill calculations don’t include basements and void spaces, so together with a basement plus an attic that would be prime for conversion, the overall area is closer to 230m².

    The budget has been for high-end specification

    Calum explains that the budget is rather difficult to define, as it’s not being constructed in the usual way. Typically a similar house might cost £2,000 per square metre, or around £470,000 in total. But as Build It’s complete guide to the house highlights, you could build the same size of house for substantially less if it wasn’t to the same high level of specification.

    By adding in the expensive finishes and details, Calum explains that it is giving people the opportunity to look at where they want to be spending their chunks of money.

    The corner plot dual aspects led much of the thought about design

    Opinder also likes the aesthetic of a steep roof pitch on a house, and to make a dramatic feature of the front he designed two gables, with the feature continuing around to the side.

    Insulated Concrete Form (ICF) was chosen as the construction method for a variety of reasons: it has good energy efficiency, is very airtight, performs well acoustically, and was particularly well suited for constructing the basement.

    Following discussions with Nudura, their ICF supplier, Opinder decided to push the design and show the materials at their best. The resulting design has a balcony that projects over the car parking area, hanging off a cantilevered wall that flies out at the first floor level. There are also frameless windows that turn the corner and are taken up to the underside of the gables.

    The ‘wow factor’ was an important consideration

    Often the space required for a plant room is underestimated, so the Build It house is a good example of showing how much area can be needed. Their plant room is in the basement to house the mechanical ventilation with heat recovery (MVHR) system, along with the inverter for the solar panels, battery storage, water softener, control hub for the Niko smart home system, and the amplifiers for the whole house sound system.

    Calum wants visitors to have the ‘wow factor’ when they walk in, so Opinder has designed a triple-height entrance hall. There you are greeted by a sculptural ash staircase that winds its way up. The eye is also drawn through towards the back of the building and the garden.

    A mixture of door types have been used, with pocket doors that slide into the walls, and a glass screen that gives the flexibility of sub-dividing the open space if needed.

    There is further architectural interest on the ground floor, with a curved wall that comes around from the cloakroom and into the kitchen, next to the floor to ceiling windows that give an amazingly light and spacious feel.

    The ground floor is open plan with lots of hard surfaces, but the oblique angles stop it from being acoustically noisy.

    The timber posi-joists, which are great for running services through, can be prone to noise transfer, so they have used acoustic boards, acoustic insulation and a screeded floor on top.

    On the first floor there is a glass balustrade which further enhances the connection with the outdoor space.

    Each bedroom is individual because of the different aspects and how they sit within the roof forms.

    It has been a typical self build journey in many ways

    The project hasn’t been without its challenges along the way.

    Calum explains that many of the difficulties have been in the project management of coordinating suppliers and contractors to work together.

    Issues were with communication, building to the same tolerances, and even incorrect measurements on site meaning that windows and doors didn’t end up exactly where they should have been.

    His tip for self builders is to keep on top of checking things like that because you could be storing up problems for a later date if things aren’t nipped in the bud as soon as possible.

    “The problems are about people and communication and scheduling things and dealing with the weather and all of those little curve balls that come your way and how you can actually try and continually pull it back to keeping it true to the vision of what you’re trying to create and as originally in the plans. Because it can be quite easy to deviate off slightly and end up with a house that doesn’t quite look and doesn’t quite perform in the way that you hoped it would.”

    The house shows what can be achieved on a tight plot

    With Calum working on the house from a Project Director level, it has been Editor Chris Bates who has been project managing the self build, going through the hard learning process and gaining valuable lessons and insights from it.

    Regular readers of Build It have been following the journey in the magazine and have been visiting to see the finished building. And for other members of the public with no prior experience of it, there are infographics around the house that help them understand the journey and the choices that were made around materials and suppliers.

    Going forward, the house will be paramount to the magazine’s editorial, as they can relate back to the experiences and decisions they made, or what they might have done differently in another scenario.

    Although the house went over budget and needed their contingency fund, (primarily due to weather delays), Opinder is keen for the house to show what is achievable on a fairly tight plot. He says it shows that it can be attainable for everybody and offers a genuine alternative to buying a typical “Noddy-box” house.

    More Graven Hill podcasts

    We’ve been following the Graven Hill scheme with interest for some time, so if you would like to know more about the background of the project and what it’s like to build there, then check out some of our previous podcasts:

    Find out more

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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.

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  • HPH150 : Where is the balance between renewables and a fabric first approach? – with Alex Baines

    HPH150 : Where is the balance between renewables and a fabric first approach? – with Alex Baines

    Despite his background in renewables, Alex Baines explains why he embraced a fabric first approach on his self build project.

    Alex Baines in his office

     

    Interview with Alex Baines

    We’ve been following the progress of Alex Baines’ Long Barrow Passivhaus self build in episodes 74 and 100. This time we’ve brought him back to the podcast to draw on his background working in renewable energy. He first became interested in the idea back in 2008 and went on to do a Masters in Renewable Energy at the Centre for Alternative Technology, before getting a job advising a mechanical and engineering company about renewables installations.

     

    Renewables were heavily incentivised to encourage meeting carbon emissions reduction targets

    Until fairly recently it seemed to many that renewables were being hailed as the solution, and the industry was heavily incentivised with feed-in tariffs and the Renewable Heat Incentive to encourage take-up. The successful promotion of the industry meant there was, and still remains, a perception that by using renewables you create a ‘green’ or ‘eco’ house.

    It wasn’t long before Alex came to the conclusion that while renewables were a great part of the solution, they should only be the final part of the solution: “because technically you can get to zero carbon by building a pretty bad building and whacking in a massive amount of renewables.”

     

    Renewables should be “the final part to get you to the bit that you can’t avoid”

    For Alex it became important to look at fabric first in the initial instance, and then consider renewables for the parts that can’t be avoided, such as electricity. Whereas with Passivhaus you can avoid the need for the majority of heating, you can’t avoid the need for electricity around the house, which is where renewables can still play their part.

     

    Reducing the energy demand of a building means fewer renewables are needed

    It was quickly apparent to Alex that Passivhaus was where his focus needed to go, because he cared about reducing the energy demand in the first instance.

    “So you look at a building, the building is the demand and the renewables are something that meets that demand. So if you can reduce the demand then you reduce the size of your generator.”

    Alex points out that renewables will eventually fail, and at that point the building will no longer for example be zero carbon, or running at an improved efficiency.

     

    A change in public perception may need to be driven by government

    Alex explains that if/when the Building Regulations become more stringent, then people’s understanding may change too, as currently there is a general lack of knowledge and promotion around it. He uses the example of Brussels – where Passivhaus standard has been adopted – which has resulted in manufacturers coming to the city because that’s where the demand is (rather than sourcing products from overseas).

     

    Passivhaus is really a ‘human comfort’ standard

    According to Alex, the current Building Regulations don’t focus on a holistic approach of what is best for the occupants. Instead they are made of separate parts looking at individual elements, for example, ventilation requirements having no link to acoustic requirements, and having no link to energy demands.

    “I would much rather we just said right, let’s go for a human element design and actually funnily enough, you focus on the human element you end up with Passivhaus because that’s where Passivhaus came from.”

     

    Long Barrow Passivhaus progress – know when you can take a pause!

    Alex had opted not to take a mortgage for his self build until they got to the airtight / watertight shell stage, so when his employment situation changed nearly a year ago, they decided to pause the project. Because they are using Insulated Concrete Formwork (ICF) as a construction method they were able to pause before getting the windows in and the waterproofing on. With other building methodologies it wouldn’t be possible to pause until they are airtight and watertight, but Alex suggests you work out at what stages you would be able to take a break if circumstances unexpectedly arose that might make it necessary.

    Work is due to recommence shortly with the insulation waterproofing going on the roof, before putting the windows in and waterproofing the rest of the building. Once the services have been connected up Alex can start on the internal layout. The internal space has been designed to be flexible, which has the benefit that Alex can work on one part while still being able to live in the other spaces. If the budget allows at the end, he will be installing photovoltaics for generating electricity and solar thermal panels to provide the hot water.

    Roof-on-Long-Barrow

     

    Find out more

    Follow Alex Baines on Twitter

     

    Transcript

    Download a transcript of the interview with Alex Baines.

     

    The Hub update

    We’re just getting ready for our next progress call, where we bring people together within the community and try and resolve any issues. It’s always interesting to see the hurdles that people are facing at the various stages of their projects.

    Our new module is about VAT refunds, explaining how the process works and what you can and can’t claim for.

    The new module also ties in with the latest video project we’re following – Buckinghamshire Passivhaus – which started out as a renovation project. After doing all their research they realised it just didn’t make sense – either financially or in terms of risk and complexity. Combined with various other reasons they decided to opt for a new build instead. If you’re a Hub member you can check out the video now, and we have the next instalment coming very soon.

     

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