Jimbouk Posted March 21, 2018 Share Posted March 21, 2018 Looking for the best way to achieve airtightness where pipes and cables go through joists. I have used Pro Clima cable grommets elsewhere, but these cable and pipes have been installed already. Wondering about cutting a grommets and sliding over or maybe using Tescon Vana tape? Was planning on puttting some felt pipe insulation in the hole too. Thoughts? Link to comment Share on other sites More sharing options...
gravelld Posted March 21, 2018 Share Posted March 21, 2018 Are they penetrating the AT layer? If not, I don't see the problem... Link to comment Share on other sites More sharing options...
Jimbouk Posted March 21, 2018 Author Share Posted March 21, 2018 Yes, they go through to a plant room, which is the other side of the airtightness layer. Link to comment Share on other sites More sharing options...
Bitpipe Posted March 21, 2018 Share Posted March 21, 2018 We penetrated the airtight envelope (for outside sockets and lights) with duct that was siga taped on the inside. When the cables were run, they were backfilled with silicone and taped. One duct per cable so it was easy to make them airtight. LE foam and judicious use of airtightness tape looks to be your best bet there. Link to comment Share on other sites More sharing options...
Roundtuit Posted March 21, 2018 Share Posted March 21, 2018 A combination of silicon and strips of vana tape. It won't be pretty, but even if it's not perfect, any leakage won't be worth worrying about, especially if you can get to both sides. Link to comment Share on other sites More sharing options...
Onoff Posted March 22, 2018 Share Posted March 22, 2018 Is there no airtight expanding foam on the market that actually works? Or is that the ones that claim it aren't airtight enough? I know Illbruck claim some of theirs is. Would have to check for any detrimental effect on cabling of course. Link to comment Share on other sites More sharing options...
nod Posted March 22, 2018 Share Posted March 22, 2018 The Blue foam that readyfix sell is about as airtight as you will find with gun foam 1 Link to comment Share on other sites More sharing options...
Onoff Posted March 22, 2018 Share Posted March 22, 2018 37 minutes ago, nod said: The Blue foam that readyfix sell is about as airtight as you will find with gun foam Do you know how airtight that is, do they give a figure? Link to comment Share on other sites More sharing options...
nod Posted March 22, 2018 Share Posted March 22, 2018 33 minutes ago, Onoff said: Do you know how airtight that is, do they give a figure? I’m not sure But I know someone who does air tightness testing and he says it’s the only one that works Link to comment Share on other sites More sharing options...
Gone West Posted March 22, 2018 Share Posted March 22, 2018 Soudal flexifoam is pretty airtight. https://ironmongerydirect-assets.s3.amazonaws.com/product-documentation/technical/481292.pdf Link to comment Share on other sites More sharing options...
Dudda Posted March 22, 2018 Share Posted March 22, 2018 The thing with foam is they degrade with time even if only slightly. Foam may pass an airtight test when newly installed but will struggle after a few years. A lot of foams are not good to have touching cables either. The best job is as Roundtuit said and some airtight mastic or silicone like Orcon F and try and cover with tape. If you get both sides you'll be fine. 1 Link to comment Share on other sites More sharing options...
Bitpipe Posted March 22, 2018 Share Posted March 22, 2018 Newton Stopaq 308 is a never curing mastic designed for waterproofing cable entry for basements etc. I used it to seal between a 110mm foul in a 150mm duct. May do the job here. Phenomenally sticky stuff.. Link to comment Share on other sites More sharing options...
gravelld Posted March 22, 2018 Share Posted March 22, 2018 Foam also gets eaten and the adhesive layer can detach. The AT figures given for foam is for the foam itself, not the foam installed, if that makes sense. Foam is not a solution for AT. Link to comment Share on other sites More sharing options...
richi Posted March 22, 2018 Share Posted March 22, 2018 3 hours ago, Dudda said: A lot of foams are not good to have touching cables That is good to know. Thank you, @Dudda! Link to comment Share on other sites More sharing options...
Jimbouk Posted April 6, 2018 Author Share Posted April 6, 2018 Thanks all. Vanatape purchased! Link to comment Share on other sites More sharing options...
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