Mike_scotland Posted March 9, 2021 Share Posted March 9, 2021 Hi Group, Me and my partner are currently working through our building warrant and SAP calcs stuff, What would be a good u value or thickness of insulation for the ground floor with UFH? Would 150mm be a enough? Link to comment Share on other sites More sharing options...
Mr Punter Posted March 9, 2021 Share Posted March 9, 2021 Yes, 150mm is good. PIR is a bit better than XPS for the thickness, but costs more. Link to comment Share on other sites More sharing options...
Mike_scotland Posted March 9, 2021 Author Share Posted March 9, 2021 So far our builder has suggested i think The external walls will be frametherm 32 150mm thick, horizontal FF ceiling 2layers totalling 400mm wool and sloping parts of ceiling will have PIR board (150mm) with 2nd board (20mm)over the face. Its all about the sap guy but i want a good insulated house, just lookong for past experiences Mike Link to comment Share on other sites More sharing options...
A_L Posted March 9, 2021 Share Posted March 9, 2021 22 minutes ago, Mike_scotland said: The external walls will be frametherm 32 150mm thick This is relatively poor at probably not lower than U=0.25 25 minutes ago, Mike_scotland said: horizontal FF ceiling 2layers totalling 400mm wool If this DIY shed loftwool, thermal conductivity 0.044W/m2 .K then the U-value will be around 0.13 31 minutes ago, Mike_scotland said: sloping parts of ceiling will have PIR board (150mm) with 2nd board (20mm)over the face. U--value around 0.20-0.22 With the floor area and external perimeter I can calculate a U-value Link to comment Share on other sites More sharing options...
Mike_scotland Posted March 9, 2021 Author Share Posted March 9, 2021 Ermmm i think its 19m length by 7.5m wide. Floor area is about 230m2 or therby. The architect reckons a B rated house but maybe not of really poor insulation. Link to comment Share on other sites More sharing options...
A_L Posted March 9, 2021 Share Posted March 9, 2021 (edited) If the ground floor is a 19 x 7.5 metre rectangle, 150mm of PIR or anything else of equivalent thermal resistance will give a Passivhaus level 0.11 U-value. Personally I think you need another 100mm on the walls and 75mm on the sloping ceiling (same material) to get U values down to 0.12/0.14 Edited March 9, 2021 by A_L minor typo Link to comment Share on other sites More sharing options...
Mike_scotland Posted March 9, 2021 Author Share Posted March 9, 2021 Yeah it is a rectangle, roughly 19m by 7.5m its 1.5 storey. I will wait and see the SAP calcs and then ask what the price would be to upgrade the insulation. So what is a good thickness level for roof, sloping ceiling, walls and floor? Or u value. Thanks, MIKE Link to comment Share on other sites More sharing options...
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