So far we have posted about our building project mainly in Finnish so now I’ll try to summarise in English for those of you who don’t speak our beautiful language.
Our partner for building the house is Natural Building Co (NBC) in Billnäs (Raasepori) who are the leading company for building straw bale clay houses in Finland. Our son Jaakko has designed the house (he will soon graduate as an architect from Oulu University) under the supervision of Kati Juola, head architect at NBC. The cooperation has been good and we have had plenty of time to plan and Jaakko has been redrawn the house details several times and even the re-planned the whole house when we decided it needed to be smaller than originally planned.
We applied for the building permission in January 2016 and we finally received the permission on 16th June so it took about 5 months. We did re-plan the house during this time because it became evident that the house would exceed our planned budget. The main principles remained the same (with one exception) but we planned a smaller house and simplified the plan. But it is still a strawbale-clay house on pillars, with timber frame, 2 massive stoves for heating, gravitational ventilation, green roof and off-grid and overall avoiding artificial materials. The only important change was that instead of a dry-toilet we changed the plan for a willow system for handling the wastewater. The willows need all the nutrients we can ”produce” so the dry-toilet was not an option anymore. (We still have the composting dry-toilet hut outside – our first building.) The two main factors why it took so long to get the building permission were, first that we re-planned the house in the middle of the process and, second that the authorities required us to have a third party opinion that the wall structure functions in a house with gravitational ventilation. To prove this NBC had to have a third party to do measurements in existing similar buildings. The other points that we presumed might be problematic for the authorities were not big issues. Gravitational ventilation – which is very rare in todays house building in Finland because of the energy efficiency requirements – was accepted without problems. Maybe because the energy in our off-grid energy-system is anyway produced on-site. Likewise the willow system was accepted. Basically we felt that we got permission for the solutions we wanted. The only thing we are still waiting for is the permission for the wind mill which is a separate application. One of our neighbours is complaining even though he doesn’t even live here.
Above I just listed the principles but each one of them would merit a full chapter of explanation. The keyword is ”Natural Building” which to us does not mean only energy efficiency but also natural and ecological in terms of materials used and impact on the inhabitants and natural systems. To us it seems that the whole house building and construction industry has been going and is still going in a totally wrong direction in overly emphasising energy efficiency over anything else. Ok – we have climate change and that requires that we build more energy efficiently. But it doesn’t make sense to build zero-energy houses which are made of artificial materials (plastics etc), depend on machinery and automation for ventilation and go mouldy and make people sick. Finland is investing huge money in buildings that are uninhabitable and need to be constantly renovated (they still stay mouldy) and reconstructed. Apparently we have stricter rules for energy efficiency than EU requires (of course EU is blamed for that anyway) and much more problems that f.ex. Sweden and Estonia which have comparable weather conditions and the same EU rules. Of course this is a money-making machine for the construction industry which is in a highly profitable never-ending cycle of building, renovation, consultation and rebuilding. (1)
We want to build differently – we want to build a healthy house!
The first principle is to use natural breathing materials in the walls and floor. No plastic moisture barriers! Breathing in a house construction doesn’t mean that air goes through the wall – it means that moisture can go through the wall and on the way it is balanced, absorbed and released by the wall material. Same for the floor and roof. This can be achieved with wood, like traditional stock houses (as long as there are no plastics or non-breathing paints used) or straw-clay constructions. The problem with stock houses is that the stock would have to be huge for it to fulfil modern insulation requirements (even though in Finland the requirements are not as strict for stock houses as for other materials). So usually modern stock-houses are insulated. This can still be a breathing material like cellulose fiber ’selluvilla’ but it is very difficult to find insulation materials that are really ’clean’. What is typically used in cellulose fibre is a lot of Borax (sodium borate) as anti-flaming agent (up to 20% of weight) and effectively also as an antimicrobial and anti-fungal material. Antimicrobial materials should not exist in a house as a house needs its microbes as much as we do! Using antimicrobial substances enhances the appearance of nasty microbes because the nice ones die much easier. For our walls this problem was solved with going for the strawbale-clay walls where pure high-quality straw bales (organic in our case) plastered with 5 cm of clay on both sides provides us with sufficient insulation. We’ll use strawbales all the way up to the ceiling in order to avoid the need to use other insulation materials in the walls of the upper level.
But we still have the insulation in the floor (400 mm) and roof (400 mm) which are a little problematic. An option we found is flax-fiber in rolls from Isolina who use soda as anti-flaming agent. Acceptable but very expensive. An other possibility is to use sawdust as was traditionally used in Finland until the 1950’s. It must be dry (fresh sawdust from the mill is not dry enough) but the main problem is that the thermal conductivity is more than double (roughly 0,1 W/m2K) compared to cellulose fibre (0,041 W/m2K) or flax fibre (0,038 W/m2K). So 400 mm insulation as planned wouldn’t be sufficient. One possibility would be a clay-sawdust mix as manufactured by the German company Holz-Lehmhaus GmbH (0,045 W/m2K) but does it make sense to transport it from Germany? However even then it would be half the price of Isolina flax fibre but still double the price of cellulose fibre.
Building the house on pillars gives us a breathing floor structure (wooden structures and insulation) and minimises the use of concrete (only in the foundation of the pillars below ground level). The visible pillars will be wood. And the idea of building the house on a concrete slab just doesn’t feel right. However even now the amount of digging and moving soil is overwhelming. Obviously people didn’t dig this kind of pits 100 years ago. This might be something we should have studied more closely but now it is too late. We did think about avoiding plastics and polystyrene (styrox) in the foundation which will be insulated with Leca (expanded clay aggregate). (In a normal building site you would put several cubic meters of polystyrene in the ground.)
The foundation should be finalised by the end of July and in August the timber frame will be put up.
The timber frame will be supplied from Antskog just 10 km from us. More about this in a later postings. The aim is that the house would be built up to the roof (including floors and insulations) by the end of August. We will be involved where there are tasks that require less skills like nailing the lumber on the roof. So up to this stage the construction will mostly be done by professionals. Having the roof on will enable us to do several things including running workshops in the next stages:
- We can build the walls with the straw bales as they now are safe from bad weather. This and the inside plastering of the walls will be done as workshops for interested participants. The workshops will be run by Charlie Jespergaard from Natural Building Co (NBC) together with Marja and held mainly in English. So there will be several 5-day workshops with drying time in between probably through September and October. Check the facebook event for updated info.
- After the bales but before plastering the doors and windows need to be installed so it keeps warm inside.
- When the roof is on the massive ovens can be built. We need heating to dry the clay plastering. Also the ovens will be built as workshops with Iiro Sahramaa from Tulisydän where Heikki Hyytiäinen has developed maybe the most efficient and clean burning massive stoves in the world. Follow this blog and our facebook page for more information about schedules.
- We can install the solar panels and collectors on the roof which also contribute to warming the house and then we don’t need to use the generator for electricity. Hopefully by then we also have the building permission for the wind mill and we can connect it to our off-grid system.
- We can prepare the green-roof.
- Outside wall plastering will be done next spring or summer so in the meantime the straw bale walls need to be protected.
The easiest way to follow the day-to day progress of the house is to join the Iso-orvokkiniitty -facebook page where we can post photos of the development more easily.