Super_Paulie Posted July 23, 2023 Share Posted July 23, 2023 Evening gents. The build-up for my suspended floor is the same as the attached image. PIR 120mm but less in places where it was necessary. My question is, the area where the support battens are, that's a void there. Would there be any benefit in running a membrane under the joists and laying in a 50mm fibreglass roll in that void area? I could also potentially friction fit/foam in another pir board of 50mm. Was just wondering if a PIR/fibreglass roll combo would provide any additional benefits. I'm aware you need twice as much fibreglass to be comparable to PIR but a mix of materials might provide untold benefits? Link to comment Share on other sites More sharing options...
SteamyTea Posted July 23, 2023 Share Posted July 23, 2023 5 minutes ago, Super_Paulie said: provide any additional benefits Sound reduction maybe. Link to comment Share on other sites More sharing options...
Super_Paulie Posted July 23, 2023 Author Share Posted July 23, 2023 2 hours ago, SteamyTea said: Sound reduction maybe. Yeah probably not really a concern seeing as it's the ground floor. I was going for the more insulation the better, seems to make sense if you can get either of the types for next to nowt/free. Link to comment Share on other sites More sharing options...
Nickfromwales Posted July 23, 2023 Share Posted July 23, 2023 1 hour ago, Super_Paulie said: Yeah probably not really a concern seeing as it's the ground floor. I was going for the more insulation the better, seems to make sense if you can get either of the types for next to nowt/free. The more the better, is the simple answer. If you can robustly add 40mm or 50mm of PIR to the existing 120mm then you'll have a very good level of insulation (U-value). What would make this all a waste of time is ventilation heat loss (drafts) around the perimeter, up behind the skirting, and tenting into the dwelling. How have you planned to kill this off? Link to comment Share on other sites More sharing options...
Super_Paulie Posted July 23, 2023 Author Share Posted July 23, 2023 I was going to go with expanding foam all around the perimeter? Seems to be the easiest way and what I've done in the past. Link to comment Share on other sites More sharing options...
Nickfromwales Posted July 23, 2023 Share Posted July 23, 2023 3 minutes ago, Super_Paulie said: I was going to go with expanding foam all around the perimeter? Seems to be the easiest way and what I've done in the past. Yup, great. Just be mindful to NOT use anything other than Illbruck 330, or you may bridge damp / cause issues. The 330 is closed cell foam, and builders sheds sell open cell, which is not the best thing for this application tbh. I buy from here LINK Link to comment Share on other sites More sharing options...
Nickfromwales Posted July 23, 2023 Share Posted July 23, 2023 Regular foam dries like the inside of a Crunchie, but the 330 is totally non-friable and you have to work hard to remove it where you've 'gone mad' with it. Remember to get a (Hozelock / other) spray bottle with a 50/50 mix of PVA/water, and spray everything liberally, immediately prior to applying the foam. The difference is night & day, as most do not realise that PU products are 'moisture cure'. Applying this into bone dry places results in the foam 'honeycombing' and not curing anywhere near as well / expanding effectively as it should. 1 Link to comment Share on other sites More sharing options...
Super_Paulie Posted July 23, 2023 Author Share Posted July 23, 2023 Understood captain 👍 If I have any left over fibreglass should I whack that in our just bite the bullet and order in more 40mm PIR? Link to comment Share on other sites More sharing options...
Nickfromwales Posted July 23, 2023 Share Posted July 23, 2023 4 minutes ago, Super_Paulie said: Understood captain 👍 It's Mr. Captain, please. The very last thing I need is dissension in the ranks! 🙄😆 6 minutes ago, Super_Paulie said: should I whack 6 minutes ago, Super_Paulie said: in more 40mm PIR? We both know you've just answered your own question. Link to comment Share on other sites More sharing options...
Super_Paulie Posted July 23, 2023 Author Share Posted July 23, 2023 💸 another week another dollar! Link to comment Share on other sites More sharing options...
Nickfromwales Posted July 23, 2023 Share Posted July 23, 2023 8 minutes ago, Super_Paulie said: 💸 another week another dollar! You only pay for, and install insulation once, you pay your energy bills every 3 months for the rest of your life. Which dollars would you choose! 1 Link to comment Share on other sites More sharing options...
Super_Paulie Posted July 23, 2023 Author Share Posted July 23, 2023 Any genius suggestions on how I attach? The top layer is resting on the battens obviously but the lower board will have nothing underneath it. Nails angled downwards slightly? I don't have the room underneath to get a driver in to attach any supports. Link to comment Share on other sites More sharing options...
Super_Paulie Posted August 8, 2023 Author Share Posted August 8, 2023 On 23/07/2023 at 22:10, Nickfromwales said: Yup, great. Just be mindful to NOT use anything other than Illbruck 330, or you may bridge damp / cause issues. The 330 is closed cell foam, and builders sheds sell open cell, which is not the best thing for this application tbh. I buy from here LINK Illbruck 330 ordered and i have all the insulation in and to be foamed. Filled the "batten void" with 50mm PIR with the 120mm resting on the battens. Would i be right in thinking that i should create an insulated barrier from where the pug/biscuit mix goes to the end of the joist run to avoid it losing heat into the wall? like this crudely drawn image (without biscuit mix shown) Link to comment Share on other sites More sharing options...
Nickfromwales Posted August 8, 2023 Share Posted August 8, 2023 7 hours ago, Super_Paulie said: Illbruck 330 ordered and i have all the insulation in and to be foamed. Filled the "batten void" with 50mm PIR with the 120mm resting on the battens. Would i be right in thinking that i should create an insulated barrier from where the pug/biscuit mix goes to the end of the joist run to avoid it losing heat into the wall? like this crudely drawn image (without biscuit mix shown) Yes, but 120mm is a lot for perimeter insulation. 50mm would suffice, and will retain more heated m2 of floor area. Link to comment Share on other sites More sharing options...
Super_Paulie Posted August 8, 2023 Author Share Posted August 8, 2023 9 minutes ago, Nickfromwales said: Yes, but 120mm is a lot for perimeter insulation. 50mm would suffice, and will retain more heated m2 of floor area. Fair enough, I've got a shed ton of 50mm left anyways. Thanks my good man, might even have heating in time for winter, who knows! 1 Link to comment Share on other sites More sharing options...
Nickfromwales Posted August 8, 2023 Share Posted August 8, 2023 8 minutes ago, Super_Paulie said: Fair enough, I've got a shed ton of 50mm left anyways. Thanks my good man, might even have heating in time for winter, who knows! Spoil yourself lol. 1 Link to comment Share on other sites More sharing options...
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