expanding foam - suitable for gaps with pipes or wires?

[iloverhubarb]

Can I use this stuff to fill gaps where a gas pipe, central heating pipe or electric wire feeds through a wall? Will the foam gently surround the pipe/wire or will it squash it/cause a fire?

Continuation of previous thread re rodents - confirmed we have a (fairly occasional visiting) rat/s not mice! All holes being filled with mixtures or wire wool, cement and this foam. Among other tactics which I won't bore you with.... Thanks

It's not strong enough to squash anything.

It won't squash the pipes but it is a bit of a pain. We had to remove vast quantities of the stuff from our kitchen as the previous owner had bashed loads of holes in the wall for various pipes without checking the size and then just filled around (badly) with the foam. It wasn't terribly efficient, as it still let lots of cold air in, and it was pretty unsightly (although usually hidden behind the washing machine etc). I also don't think it was a great idea to have a load of it behind the cooker, as I worried about the fire risk, but I'm not sure whether that was a real risk or not.

When we redid the kitchen, we had the outside wall bricked up as much as possible and then new plasterboard fitted inside to cover the gaps and it was much better, both visually and from an insulation point.

Thanks both of you. Will go ahead to fill specific gaps without that concern then.

lilystar the detail you give is useful. If we were taking out the kitchen it would be alot easier to do everything properly. As it is I've been lying on the floor trying to get behind things to make sure that every single gap is filled, and the foam is useful for the hard to get to bits of floor to wall gap as well as wall holes. Bit of an emergency.. I assume once the foam's out of the can it's no longer a fire risk, but not using behind cooker!

What a great way to spend the extra time I had today.... Need

you should not apply it to electric cables. Many rigid plastics in contact with the cable sheath will leach the plasticisers out of the PVC (polystryrene foam does it as well). This looks like a sort of sticky wet glue on the surface, and the cable sheathing and insulation look shrunken and cracked. You can imagine that cracked or broken insulation on cables is undesirable. To avoid this, protect the cables by putting something over it. A bit of plaster or filler would be more suitable for a hole that cables go through.

If the cable is in a plastic or metal conduit, you can apply plastic foam without damaging the cable inside. However this is very rare in modern domestic installations due to addition cost and time.

There is also the issue that putting thermal insulation on cables causes it to overheat when under load. If it is just a few inches entering a wall this is not significant though.

BTW if you have not used plastic expanding foam before, be aware that it is astonishingly sticky, and will swell up out of the hole you squirt it in. It will stick to your skin, clothes, hair, eyeballs, the wall, the floor, and if you accidentally tread it into a carpet it will never come out. Have lots of disposable gloves handy, and a water mist spray to make it set hard, and wear protective clothing and a hat. You can use cling film to protect nearby objects, or tape newspaper on the wall and floor.

PJ really useful, thank you. In fact we have used it minimally, and under one electric wire only - I'll have a good look at this tomorrow and see if I can carefully cut out the foam. Will switch off electrics first!

Found it a pain actually, all the things you say in your last para dead right. Sticky patch on laminate, sticky patch on mat. We are unscathed, but I will go back to cement and filler, which I can use in a controlled manner....

you can get a tin of a product called "Foam Eater" from places that sell the foam. it does.

I think acetone nail varnish remover might also work but have never needed to use it.