WikiHouse, Sheffield: could this be the solution to the UK’s housing crisis?
Case study: the first WikiHouses to be built by a housing association
Project date 2018
Team:
Open Systems Lab, product design - Alastair Parvin
Architecture 00, architect - Clayton Prest, David Saxby
Chop Shop, manufacturer
Castle Building Services, constructor
Mascot Management, construction management
South Yorkshire Housing Association, client - Christine Davies
South Yorkshire Housing Association is the first housing association in the country (world?) to build a WikiHouse. Why did we do this?
The short answer is that in England we need to build more houses, better and faster, to hit the target of 300,000 new homes each year that is needed to tackle our housing crisis.
And we think WikiHouse could be part of the answer.
The longer answer is that while WikiHouse shares the benefits of other offsite construction methods - better/more airtight build quality, lower energy costs, higher environmental sustainability - it has some extra features which set it apart. These include: open source design, opportunities for citizen-led building, easy adaptation and distributed manufacture.
It was these features which made us want to test WikiHouse as an offsite construction product.
This post tells you:
#1 Why we chose WikiHouse
#2 What we learned from our WikiHouse test
#3 What we like about it.
“South Yorkshire Housing Association deserves an enormous amount of credit for having a very clear, brave and values-driven approach to pioneering innovation; and then sharing this innovation and the lessons in a way that allows other housing associations and councils around the country to take it, learn from it and replicate that model. Which is now what we see happening.”
#1 Why WikiHouse?
The housing crisis in England
wikihouse frames being delivered to site from the factory
photo open systems lab
An estimated 8.4m people in England are living in unsuitable housing including overcrowded, unaffordable or sub-standard homes according to a report published by the National Federation of Housing, the body which represents social landlords.
Although last year we built 240,000 new homes in England, the highest figure for almost 30 years, only 1 in 6 of these were built for affordable rent, despite this being the market sector most needed. The Nat Fed estimates we need 90,000 new affordable homes every year for the next decade to help end the crisis.
The Farmer Review published in 2016, subtitled ‘modernise or die’, looked at how the construction industry needs to change to deliver the number of new homes we need. It advocated that the industry should embrace offsite construction at scale, homes that are partially or wholly built in factory conditions.
Offsite construction, as well as building faster should allow us to build better: homes with a lower carbon footprint and lower running costs.
Testing offsite construction
We tested the LoCal Homes closed panel timber frame system in Maltby near Rotherham
A group of the largest Housing Associations in the north of England, Homes for the North, is exploring which offsite products would work best for social housing and whether by working collectively we can create a pipeline of orders that will make their manufacture more viable and therefore more affordable.
A study led by Tim Hall of Build Offsite has short listed a number of manufacturers who seem to fit the bill including WikiHouse.
South Yorkshire Housing Association owns some 6,000 homes across Sheffield City Region. We work exclusively in this geography and are committed to helping solve local problems, including by building as many new homes as we can for social/affordable rent and shared ownership.
We are always looking to build faster and better and have to date tested two offsite products: LoCal Homes closed panel timber frame and WikiHouse. Both schemes have been supported by Homes England through its Shared Ownership and Affordable Homes Programme - thank you!
We chose LoCal Homes because it had been tried and tested by Accord Housing Association (who own the product). We knew it would work for our customers and our business. And any profits would go back into building more affordable homes. What’s not to like?
Our WikiHouse pilot
“If you ever had a meccano kit..or put a jigsaw puzzle together..those two skills are perfect for putting this type of house together ”
We chose WikiHouse because it is part of a wider concept of citizen-led housing developed by Alastair Parvin and WikiHouse Foundation which was itself established by Architecture 00. This video tells you more about the thinking behind WikiHouse.
We were interested in testing a product that could work for self/custom build homes as well as for our portfolio of homes for rent. And it chimed with our thinking about frugal innovation. We also feel it is important to test experimental products alongside more established ones.
WIkiHouse is a form of offsite construction. The plywood frame is cut on a CNC machine using digital files and assembled like a jigsaw using a step-by-step manual.
We worked with Alastair and Architecture 00 to develop and test our two-storey Sheffield house.
And we worked with local businesses Chop Shop, Castle Building Services and Mascot Management to deliver the two houses.
We built 2 semi-detached homes on a plot of land we owned in Sheffield, close to the city centre.
We wanted primarily to test whether these homes would work as products for our portfolio of rented homes rather than as a citizen-led model.
The scale of the project combined with the little-known construction technology meant that a standard design & build contract was not an option. Instead we ran a construction management contract.
There were major undetected problems in the ground which meant that the project as a whole went significantly over programme and budget. In our evaluation we have however separated out the WikiHouse test from the rest of the scheme.
the plywood frames are cut on a cnc machine
photo open systems lab
the frame is then assembled like a jigsaw
photo open systems lab
#2 What we learned from our WikiHouse test
We wanted to test through the pilot:
#1 How the product would perform for our customers, our business and for the planet
#2 Whether it could deliver better value for money than traditional brick and block
#3 Whether it would be fit for purpose for a Housing Association across a range of parameters including customer satisfaction, repairs and maintenance, insurance & mortgageability, life cycle costs, scalability etc
Key outcomes
Our customers are very happy with the finished product:
“What can I say? It’s perfect!”
“It’s not that much different from living in any other house except that it’s warm.”
the finished sheffield house
The completed homes (excluding substructure) were an estimated 33% higher in cost than the traditionally built version on a nearby site in Sheffield. However we estimate that if we did it again, having learnt from the pilot, the premium would reduce to 12%.
And that if we could ensure efficient construction, including timely connection of utilities, through better up-front planning then the all-in cost could be competitive mainly because of the shorter time on site. (The programme for our LoCal Homes test was 25% shorter than a traditional build.)
We have had zero defects which has delighted our customers (and our development team).
We are monitoring the environmental performance of the homes including thermal performance, humidity, energy efficiency and the impact on customers’ fuel bills and quality of life. So far anecdotal evidence from customers is that their homes are warm and bills are low.
We had no problem insuring the product but we had a challenge with the warranty: we were let down well into the construction process by our insurers who told us the warranty had been mis-sold to them. We were able to secure a different warranty before the final grant claim but as warranty is a condition of Homes England grant we had a few sleepless nights. This is one of the challenges of a new and unfamiliar product.
It is too early to say how the product will perform in terms of life-cycle costs. We believe, in principle, it is scalable.
Design & planning
“As a designer you have more control over certain design elements and more impact on how those designs get built.”
It is easy to adapt the design by using the WikiHouse toolkit, a system which stretches or reduces house types and their corresponding floor plans.
The toolkit is designed to allow the self-builder to analyse and control costs at each stage but doesn’t include all the other costs associated with delivering multiple homes by a building contractor. It would be great if the toolkit could be adapted to do this.
The design is currently about the house - the “box” itself - but it doesn’t consider in detail how it interacts with the ground/site. More thinking on this is needed up front.
Future schemes should be easier, quicker and cheaper to design now that a model that suits our requirements as a housing association has been developed.
We were keen to avoid all wet trades in the test. We therefore proposed a dry cladding (fibre cement tiles) which was controversial with planners but got approval in the end.
The post-planning period was problem free but, as with all offsite construction projects, greater time and attention should have been given before construction started to on-site logistics, programme scheduling and ordering utilities etc. This would have prevented delays later.
The pilot has enabled Architecture 00 and WikiHouse Foundation to learn, refine and revise the product. Like all new offsite products, it needs a few iterations for the manufacturer and the buyer to find out what works best.
Revisions need to include a more detailed assembly manual and development and improvements in instructions for all parties; and refinements to the product itself - for example access to pipework/wiring would be easier if a services channel was recessed so no battens are needed and the plasterboard lining can be fixed directly to the plywood walls.
photo open systems lab
photo open systems lab
Manufacture and construction
“Very hot, very tiring but very rewarding. Once the frames are built it’s very fast in going up.”
photo open systems lab
We wanted to do a small pilot and the plot we chose was a tight urban site. This made on-site storage and assembly challenging: a crane would have been useful to raise the second house as the site was even tighter by then.
Manufacturing was quick. But Chop Shop had to store the materials until the site was ready.
Given the extent of offsite manufacture in this product there is a clear advantage in using a factory environment to store, sort and conduct the frame stage of assembly. This also makes lifting and handling easier from a workers’ safety perspective, shields materials from the weather and creates a suitable work surface.
photo open systems lab
This means you need enough warehouse space for storage as well as assembly. And storing the product offsite requires a strict “just in time” approach to delivery. It would be better if the manufacturer and assembly were done by the same people. Again, this is no different from many offsite products.
Efficient cutting of the plywood sheets to minimise material waste needs to be balanced against the efficiency of the assembly process. In our case WikiHouse chose the former (commendably sustainable in terms of materials) but it was labour intensive and time-consuming for Castle Building Services to sort all the pieces ready for assembly. The instruction manual - Ikea style but the size of a telephone directory - was very complicated and took some figuring out.
The timber frames were small enough to be delivered to site in a transit van rather than via a lorry which was both cost effective and easier to manage. Chop Shop was only 1 mile from site.
It took about a week to build the two frames and they were erected in a couple of days. The cladding, waterproofing and the rest of the structure took a couple of weeks.
The second home was much quicker to erect than the first because the team understood how it worked after completing just one. They felt that the process would get faster on a bigger scheme. Even so, the WikiHouse was faster to first fix than its block and brick comparator.
Overall more planning is needed up front, for example in the sequencing of manufacturing the parts and of the different trades. CDM is also more challenging with a new product.
Conclusions
“So would we use it again? The answer is yes but.... we would want to do another small site before trying it on a big scheme. ”
We feel that WikiHouse has the potential to be well-suited to a larger housing association scheme in future: it works for our customers, is scalable and a suitable house type for many housing associations.
WikiHouse is currently more expensive as a product than traditional build but on a larger site and with more experience it could prove to be a competitive alternative, especially if the cost of ply reduces.
It is however still in its early stages of development and further product testing and development is needed before a big scheme is proposed.
This pilot contributed greatly to the development of the product and all those involved invested in learning - it would make sense for the same team to collaborate on a second site to consolidate that learning.
One challenge on a bigger scale would be the maturity of the market. Although local capacity could generate, say, 50 homes a year, manufacturers may need to be bigger and to understand that they are engaging in a manufacturing process not just producing a product in order to service a big development of 50+ homes on a single site.
#3 What we like about WikiHouse
There is a plethora of offsite construction products out there - what was it about WikiHouse that made us want to test this? Lots of reasons:
Image by Open Systems Lab
Open source design
The design is digital, flexible and shared as a set of open source digital files, which means anyone in the world can access them for free. WikiHouse is developing software tools to make it easy to alter the design to suit different sites and to stretch or reduce housetypes and floor plans. As a charitable housebuilder we like the idea of sharing knowledge.
Image by Open Systems Lab
Co-production
At South Yorkshire Housing Association we have trail-blazed co-production in LiveWell, our supported housing services, and co-designing, co-producing and co-evaluating everything we do with our customers is important to us. We were interested in learning about the WikiHouse, partly because it could be a key enabler for a new citizen-led way of building homes.
We didn't test this in our pilot, because we wanted to build the homes for our own rental portfolio so that we could learn how they perform long term, but it was a reason for doing the pilot.
Lower energy bills
WikiHouse should be more affordable to live in. One of the attractions of offsite construction methods, where houses are manufactured and assembled in factory conditions, is that the buildings should be better built and less "leaky" in terms of heat. This makes them cheaper and easier to keep warm and dry..
In the case of WikiHouse, the plywood structure is supplemented by thick insulation covered in ply panels which makes the house super-insulated. The houses are new and we are still monitoring how well they perform but our customers tell us they are warm and bills are low. We’ll keep you posted.
Image by Open Systems Lab
Image by Open Systems Lab
Sustainable materials
It's made of wood and has a very low embodied carbon footprint. We like wood because it is the most sustainable building material there is. Part of South Yorkshire Housing Association’s purpose is to be here for the long term and so sustainability really matters to us. It would be even better if the structural timber sheets were grown locally; ours were imported from Finland.
Image by Open Systems Lab
No wet trades
WikiHouse comprises only "dry" trades. Offsite construction is generally better, faster and less messy (especially for the neighbours) than traditional ways of building but often a product comes to site and then requires finishing with wet trades.
The WikiHouse lends itself to being clad with dry finishes such as the fibre cement tiles we used on our pilot. This is helpful given that bricks and bricklayers are often in short supply and/or expensive. Also there is no wet plastering inside.
Image by Open Systems Lab
Easy to maintain and adapt?
We like efficiency and one of the features of the WikiHouse is that it comes with an assembly manual that shows where all the pipework, wiring etc goes. Our Home Maintenance Team observed how the WikiHouse was assembled and understands how it works. This should make it easier to maintain and adapt. It's early days but we'll let you know.
Image by Open Systems Lab
Local & distributed manufacture
One of the great things about the WikiHouse is that it doesn't need a big factory. It just needs a CNC cutter and a roof or tarp to keep the ply dry. This means that small local firms can make it, which cuts down on transport costs and fuel.
Our homes were built by Chop Shop in Sheffield whose workshop is less than a mile from the site. Parts were delivered to site as and when needed in small vans (because it comes in small pieces). Developing WikiHouse technologies for pre-assembly offsite as whole beams and frames would reduce the complexity of organising small parts for assembly on site
If we wanted to build at scale we could access a network of manufacturers. This might mean higher transport costs but not the high cost of setting up a new factory. Nor the need to maintain a pipeline of work in order to keep it in business.
That said, there could be complexity in coordinating a network of manufacturers, storage etc so I suspect this idea works better in theory than practice for a large-scale development. Investing in our own on-site cutter might be an option.
Image by Open Systems Lab
New construction skills and jobs
There is a national shortage of construction labour but the WikiHouse can be built by joiners and even by relatively unskilled labour. We used a local firm, Castle Building Services, for most of the work on ours.