Bonner Posted February 10, 2022 Share Posted February 10, 2022 Roof going on soon, I need to decide which insulation material/system to use. It is included in main contract but spec says “160mm K7 or equivalent to give 0.20 W/m2K”. I am aware this is min building regs so will be upgrading ... Builder wants to use Actis (Hybris and H Control) to save labour cost. Kind of like the H Control as a continuous layer but not at all sure about Hybris! I don’t want to push for PIR because I know it will end up with loads of gaps and I can’t be there to supervise. Would 200mm loft roll be easy enough to install from the underside, ie. self supporting until plaster boarded or would we need to use batts? I have plenty of space for insulation between and below rafters; raised tie trusses with 360mm rafters! What is the best balance of benefit vs cost? Link to comment Share on other sites More sharing options...
PeterW Posted February 10, 2022 Share Posted February 10, 2022 2 minutes ago, Bonner said: Builder wants to use Actis That isn’t your spec - who’s paying ..? 2 minutes ago, Bonner said: Would 200mm loft roll be easy enough to install No because it’s the wrong product - you need something such as Frametherm. 3 minutes ago, Bonner said: 160mm K7 or equivalent to give 0.20 W/m2K 160mm of K7 (which would be 2 layers of 80mm) is not anywhere close to 0.20 - it’s more like 0.13 or lower with insulated plasterboard so something is amiss Link to comment Share on other sites More sharing options...
Russell griffiths Posted February 10, 2022 Share Posted February 10, 2022 I’m not surprised your builder wants to use actis, it will save him thousands in labour cost. But it’s your house and your spec. Do you not have a drawing. 160mm of k7 is a good spec. If your worried about fitting then get a spec for the product and tell them that is the standard it needs fitting to, end of. Fit it correctly or f##k off. This insulation should have a layer underneath the rafters as well, to mitigate against cold spots through the joists. There is a product that expands to keep the insulation fitting tight. If your having a fight with the builder buy some of the GAPO TAPE to make his life easier. What is happening with a vapour control layer. 1 Link to comment Share on other sites More sharing options...
redtop Posted February 10, 2022 Share Posted February 10, 2022 The way its worded so long as he gets to 0.2 he can use anything provided its suitable for the installation 1 Link to comment Share on other sites More sharing options...
Bonner Posted February 10, 2022 Author Share Posted February 10, 2022 54 minutes ago, PeterW said: That isn’t your spec - who’s paying ..? Unfortunately the spec says ‘or equivalent’ so I just getting ready for battle ... 56 minutes ago, PeterW said: No because it’s the wrong product - you need something such as Frametherm Thanks, I will look at that 57 minutes ago, PeterW said: 160mm of K7 (which would be 2 layers of 80mm) is not anywhere close to 0.20 - it’s more like 0.13 or lower with insulated plasterboard so something is amiss Architects building regs spec, I will ask them what they were thinking ... Link to comment Share on other sites More sharing options...
Bonner Posted February 10, 2022 Author Share Posted February 10, 2022 48 minutes ago, Russell griffiths said: I’m not surprised your builder wants to use actis, it will save him thousands in labour cost. But it’s your house and your spec. Do you not have a drawing. 160mm of k7 is a good spec. If your worried about fitting then get a spec for the product and tell them that is the standard it needs fitting to, end of. Fit it correctly or f##k off. This insulation should have a layer underneath the rafters as well, to mitigate against cold spots through the joists. There is a product that expands to keep the insulation fitting tight. If your having a fight with the builder buy some of the GAPO TAPE to make his life easier. What is happening with a vapour control layer. Drawing also says ‘or equivalent’ so I am going to have a battle with the material spec ? I work away a lot so the builder can fit the insulation and cover it before I can inspect Ultimately I can tell him to do it properly and leave it for me to inspect but this will delay completion which is already well overdue. I want to work with him if there is a good cost effective solution, considering material and labour. Will look at the VCL aspect, thanks Link to comment Share on other sites More sharing options...
redtop Posted February 10, 2022 Share Posted February 10, 2022 1 hour ago, Bonner said: Drawing also says ‘or equivalent’ so I am going to have a battle with the material spec ? I work away a lot so the builder can fit the insulation and cover it before I can inspect Ultimately I can tell him to do it properly and leave it for me to inspect but this will delay completion which is already well overdue. I want to work with him if there is a good cost effective solution, considering material and labour. Will look at the VCL aspect, thanks Provided its equivalent and used in a way thats approved why do you care? If you wanted to be more specific then the price would have changed. Link to comment Share on other sites More sharing options...
crispy_wafer Posted February 10, 2022 Share Posted February 10, 2022 (edited) Is this a dormer roof type construction? If so then stick to your guns - the k7 kooltherm or equivalent is what you want for a proper job (the Pink stuff) or PIR minimum (white/yellow stuff), Actis Hybris wont be enough to satisfy your drawing and your SAP calcs .033 wmk vs k7 @ .018wmk (not that I know what that means... Lower the better?) Standard PIR is at .022 ish I think. @Russell griffiths has got it spot on. Gapotape is ok I bought some but in then didnt bother using all of it as I was having great results cutting the PIR to fit (Straight edge/clamps and a festool isc) Sorry edit... 360mm rafters does give a bit of wiggle room to alter from PIR to something a little easier to handle and install correctly. Playing with UBAKUS may help. Edited February 10, 2022 by crispy_wafer Link to comment Share on other sites More sharing options...
PeterW Posted February 10, 2022 Share Posted February 10, 2022 But 0.2 isn’t building regs (new build) so I am intrigued at what the actual BRegs / SAP spec is that has been signed off ..?? If you’ve got 350mm to spare, then I would go with 3 layers of 100mm Frametherm overlapped then a 25mm layer of PIR / K7 below rafters and taped which will give you your VCL if done properly. That’s a massively thick insulation layer and will also work well on sound absorbtion. 1 1 Link to comment Share on other sites More sharing options...
Thorfun Posted February 10, 2022 Share Posted February 10, 2022 with 360mm rafters could you potentially consider blown in cellulose to fully fill that space? I guess you might have to get someone else to do it as I believe it's specialised but maybe get the cost taken off from the builder and use that money to get someone else to fit. just a thought. 1 Link to comment Share on other sites More sharing options...
PeterW Posted February 10, 2022 Share Posted February 10, 2022 1 hour ago, Bonner said: Unfortunately the spec says ‘or equivalent’ so I just getting ready for battle ... Why ..?? Is this a fixed price contract ..?? And anyway, Hybris isn’t equivalent to 160mm of PUR so that cannot be classed as the same. 1 hour ago, Bonner said: the builder can fit the insulation and cover it before I can inspect Ask for photos - not unreasonable. Link to comment Share on other sites More sharing options...
Bonner Posted February 10, 2022 Author Share Posted February 10, 2022 1 hour ago, redtop said: Provided its equivalent and used in a way thats approved why do you care? If you wanted to be more specific then the price would have changed. I have read some negative reports about Actis stuff, not fire retardant, not BBA approved? Anyway lesson learned I should have been more specific in the beginning, just went with the building regs spec. Link to comment Share on other sites More sharing options...
Bonner Posted February 10, 2022 Author Share Posted February 10, 2022 1 hour ago, crispy_wafer said: 360mm rafters does give a bit of wiggle room to alter from PIR to something a little easier to handle and install correctly. Playing with UBAKUS may help Correct, I can increase the depth of lower performance material. I will have a play with UBAKUS. Cheers Link to comment Share on other sites More sharing options...
Bonner Posted February 10, 2022 Author Share Posted February 10, 2022 58 minutes ago, PeterW said: I would go with 3 layers of 100mm Frametherm overlapped then a 25mm layer of PIR / K7 below rafters and taped which will give you your VCL if done properly. That’s a massively thick insulation layer and will also work well on sound absorbtion. Thanks Peter, just what I was looking for. I will price it up for comparison Link to comment Share on other sites More sharing options...
Bonner Posted February 10, 2022 Author Share Posted February 10, 2022 43 minutes ago, PeterW said: Why ..?? Is this a fixed price contract ..?? Sorry, should have said that in the beginning. Fixed price contract with loose specification, lesson learned! 1 Link to comment Share on other sites More sharing options...
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