Barny Posted April 16 Share Posted April 16 Hi. Has anyone done a passivhaus (aiming for) timberframe using block and beam foundations but not using Tetris? Our foundation design currently uses Tetris to keep the thermal bridging down but it is coming out 50% more than a raft (which we can’t have due to site conditions) and 100% more than traditional block and beam with 200mm of PIR. Just wondering if anyone else has achieved near passivhaus using block and beam and can share foundation designs? thanks Link to comment Share on other sites More sharing options...
Thorfun Posted April 16 Share Posted April 16 can't you just use normal block and beam and put loads of insulation on top? 🤷♂️ 1 Link to comment Share on other sites More sharing options...
Thorfun Posted April 16 Share Posted April 16 ps. have a read of this thread as the OP was also told couldn't have an insulated raft due to ground conditions but their SE made it possible. Link to comment Share on other sites More sharing options...
Barny Posted April 16 Author Share Posted April 16 17 minutes ago, Thorfun said: can't you just use normal block and beam and put loads of insulation on top? 🤷♂️ I think there will be thermal bridging issues between the block and frame. Has anyone got a design that works around this? Link to comment Share on other sites More sharing options...
Iceverge Posted April 20 Share Posted April 20 @ProDave did a suspended I joist floor with a screed on top. Search his recent posts. Added to his external woodfiber layer it should have excellent thermal bridging characteristics. Or like @Thorfun says just shove lots of insulation on top of block and beam. Perimeter thermal bridges are pretty straightforward to deal with for timber frame anyway. What's your planned wall build up. Link to comment Share on other sites More sharing options...
IanR Posted April 20 Share Posted April 20 On 16/04/2024 at 11:26, Barny said: (which we can’t have due to site conditions) Have you looked at all options of raft? Ie. Rafts with piling support. Link to comment Share on other sites More sharing options...
Roundtuit Posted April 20 Share Posted April 20 On 16/04/2024 at 11:48, Barny said: I think there will be thermal bridging issues between the block and frame. Has anyone got a design that works around this? Marmox blocks. I looked at them for ours, but in the end decided the benefit was neglible as we had continuous 40mm pir layer around the inside of the frame. Link to comment Share on other sites More sharing options...
JohnMo Posted April 20 Share Posted April 20 This is a construction detail for block and beam from the Durisol build manual it may be some you could use or modify. 2 hours ago, Roundtuit said: Marmox blocks. I looked at them for ours, but in the end decided the benefit was neglible as we had continuous 40mm pir layer around the inside of the frame. I also looked at Marmox, and once I had been through the calculations, couldn't see the benefits. I constructed as per the below, but with the additional 70mm upstand not shown on the screed perimeter. My slab isn't block and beam, but similar in many respects, but ground bearing, see image above for an idea - 160mm reinforced slab on numerous stub walls, cast in place. Then insulation, then a further cast concrete floor. Link to comment Share on other sites More sharing options...
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