Fill hole around copper pipes

[grimbouk]

Hi,

I have several copper pipes (hot and cold) that enter my loft from my kitchen and bathroom (I live in a bungalow). The pipes have quite large holes around them (up to 3 cm in one case!).

I want to fill the holes mainly for insulation reasons, I'm not too worried about appearance. What's the best way to achieve this?

I've been reading forum posts and saw some people advise NOT to use expanding foam. Can I just fill the holes with one of the hole filling compounds? Will the pipes expand when the heating is on causing the filler to crack?

 

[DAZB]

Expanding foam is designed to fill holes including around pipes etc so as long as you don't get trigger happy a small application will expand nicely and then trim off the excess once cured.

 

[stevethejoiner]

I would also go with foam, but an additional tip for large holes is to cut some cardboard or paper to slip around the pipes and tape upto the ceiling before foaming up. Make or leave a tiny hole for the foam gun tube and then foam it up. Then the wet foam will rest on the cardboard and expand up and over the ceiling board rather than keep falling out in sticky lumps into the room before it sets.
When it has set the card will just peel off and you wont have muck cuttting back of foam to do.

 

[grimbouk]

Thanks stevethejoiner,

As the ceiling is only plasterboard thick, I wasn't sure foam was the way to go ( ie a wide but not deep hole).

So it sounds like you would fill the holes from the loft above against the card, how much foam would you use? Would you try to keep it shallow and in the hole? Or would it be better to overfill, causing more of a cap?

This would give more surface area for the foam to stick too wouldn't it? ( the top of the plaster board along with the side)

 

[stevethejoiner]

It will expand out and up. If you not worried about the look of the foam in the loft leave it as is when set hard. When you peal off the card you can carve away at the hardened foam to allow you to patch with plaster. As to how much foam to use, I would say apply adequate so that you have covered the hole and a little more around the pipes. When the foam sets hard around the pipes it will help key it all together.
Foam is also moisture activated, so lightly dampen the existing plasterboard you want it to stick too.

 

[grimbouk]

great, thanks for the advise

 

[stevethejoiner]

great, thanks for the advise

And wear the disposable gloves that should be pushed up in the cap unless you want hands stained black for a week because no matter how careful you think you will be, something always happens, so somehow you will end having the long nozzle transferring wet foam onto your hands. Ah, you said you were working in the loft, I will add ,elbow, knee, earlobe, to the list as well.