marekk

Hi all Thought I'd introduce myself after lurking for a while, taking in the advice and discussions. I'm starting to plan a second self build after a gap of 25 years. The first build was to start a family in and this new one will be to retire into. I'm on a bit of a journey, born in London to Polish parents who came to the UK after WWII, met my wife and then built the aforementioned house in Scotland, I now want to retire to Krakow in Poland where I already have a holiday apartment, i.e. going back to my roots. The last build was brick and block where the shell was constructed by a builder and then I got all the other trades in. I installed UFH and MVHR myself, which the various trades found fascinating. This time around I want to go down the prefabricated route and get as close to passive as budget will allow. I want to include PV and ASHP and repeat the use of UFH and MVHR which we found to create a brilliant environment even though I've now realised the lack of air tightness meant the full benefits of MVHR were not realised. Searching around for timber frame suppliers in Poland, the main ones I've found all construct using wood construction and insulating materials from Steico. I've seen a number of posts here where Steico i-joists or wood fibre insulation have been used, so that's reassuring. I'm also drawn towards a twin stud frame as supplied by MBC, but no Polish firm seems to offer this. The closest in performance has the following wall structure from outside to in: 6-9mm render 60 mm Wood fibre insulation board (Steico Protect) 300 mm Wall construction using I-joists/LVL/KVH with either blown or flexible wood fibre insulation (Steico Zell / Flex) 15 mm OSB-3 board Vapour barrier membrane (Steico Multimembra 5) 60 mm Flexible wood fibre insulation (Steico Flex) between battens 12mm OSB-3 board 12.5 mm GKFi fire resistant plasterboard I'd gladly welcome any opinions on this. There is one other interesting prefabricated method I've found - concrete sandwich wall panels filled with 20cm of PIR giving a U value of 0.11W/m2*K . The exterior wall finish can be customised for texture and colour ,so no need for any render or other cladding. The walls can have holes, channels or grooves for services incorporated so interior finish can also be left in the currently fashionable concrete or painted once you get fed up with it! So it looks like you can get to fairly finished state in terms of walls in rapid time - assuming you have pre planned all your service runs and terminations ahead of time, as there will be no easy way of fixing these after. Ceilings can also be of concrete construction. Roof is timber. Plus points include high thermal mass and good acoustic insulation. Drawbacks to my mind is these will be fairly hefty panels, so will require good access for the large supply vehicles and crane. I'd also think the foundations, which can be any type to suit the ground conditions, would need to be pretty bang on in terms of level. Can anyone think of other possible issues? Thanks Marek