Airtightness advice - cables and pipes

[Jimbouk]

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?

[gravelld]

Are they penetrating the AT layer? If not, I don't see the problem...

[Jimbouk]

Yes, they go through to a plant room, which is the other side of the airtightness layer.

[Bitpipe]

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.

 

 

[Roundtuit]

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.

[Onoff]

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.

[nod]

The Blue foam that readyfix sell is about as airtight as you will find with gun foam

[Onoff]

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?

[nod]

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

[Gone West]

Soudal flexifoam is pretty airtight.

 

https://ironmongerydirect-assets.s3.amazonaws.com/product-documentation/technical/481292.pdf

 

 

[Dudda]

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.

[Bitpipe]

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..

[gravelld]

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.

[richi]

3 hours ago, Dudda said:

A lot of foams are not good to have touching cables

 

That is good to know. Thank you, @Dudda!

[Jimbouk]

Thanks all. Vanatape purchased!