As it took a while to get the website and blog up and running, my first blog comes as we await the first floor PC slabs for the flats. For historical purposes, 400mm of Dow Floormate was placed without difficulty beneath the 300mm RC rafts, and the insulation is now all nicely wrapped up and backfilled. All the service penetrations were installed ready to receive air tight grommets and the blockwork commenced.
Most Passivhaus’s in the
are built by enthusiasts for enthusiasts, but at Wimbish we are trying to build them in a normal commercial volume house building environment. That means getting your everyday subcontractor to understand the process and the importance of quality and detailing that wouldn’t normally apply in this environment. UK
Initially this included making sure the Aircrete thin joint blockwork was laid fair face to the outside rather than the inside, as the insulation has to be fitted later with no air gaps between the sheets.
Our air tightness barrier is to be the wet plaster but where we pass through the first floor void the ground and first floor plaster skins are linked by a Solitex Plus airtight membrane. Initially we had proposed PC slabs even in the houses because of the ease of obtaining this air tight seal, but value engineering changed this to timber posi-joists which present a few more challenges, particularly with restraint straps and in the corners. Several mock ups and some significant time and effort on site has been expended to ensure this is properly placed and installed.
So, the PC slabs should arrive on Monday for the 6 flats and then we can speed ahead to getting the roof trusses on. The next passivhaus task will be the air tight membranes at ceiling level, and then maybe a preliminary air test before plaster to see how we are doing.
Parsons + Whittley Architects
17th October 2010