Filling gap after moving radiator

Discussion in 'Plumbers' Talk' started by ASIF HUSSAIN, Dec 1, 2021.


    ASIF HUSSAIN New Member


    I've just had a new tall panel radiator installed. I originally had a regular radiator on the wall next to it so the guy chiselled a channel from original radiator location around to the next wall.
    It's a 10 year old house and the holes are about 1.5 inches deep. The pipework for radiators is plastic
    I need to fill sand and paint. Can I use expanding foam filler ?
  2. woodbutcherbower

    woodbutcherbower Well-Known Member

    I'd be inclined to use plaster, Asif. You can buy patching plaster in small bags. Mix it up fairly stiff so it doesn't slump, smooth it using a wet filler knife, wait till it dries, then sand & paint.

    ASIF HUSSAIN New Member

    I tried some ready mixed plaster which I got from b&q earlier and it didn't work. Some of the gaps are about 3 inches deep.
    I've seen the no nonsense fire rated expanding foam on Screwfix. Would that do the job
  4. tehvlb

    tehvlb Member

    The trouble with expanding foam is it doesn't take a coat of paint, if your gap is 3 inches then just layer in plaster over a few days.

    ASIF HUSSAIN New Member

    I'm planning on applying a coat of plaster once I've sander the foam down. That should work shouldn't it
  6. WillyEckerslike

    WillyEckerslike Screwfix Select

    How thick are your walls Asif? Three inches is a deep chase if I've understood you correctly. You should only chase ⅓ of the thickness vertically and ⅙ horizontally. I think I'd be protecting the pipes and using a strong sand and cement mix
  7. DIYDave.

    DIYDave. Screwfix Select

    Not best practice to plaster / cement / the pipes in directly, regardless of them being copper or plastic

    Apart from possible corrosion issues from cement being in direct contact with copper - and yes, I know you’ve said plastic pipes - you need to allow for a tiny amount of expansion from these pipes (copper or plastic) and just bunging in a load of ‘muck’ won’t allow for this

    Result may be cracked plaster and as the pipes heat up and cool down, a really annoying ticking noise from inside the wall (not guaranteed, you might just get away with it)

    Expanding foam will insulate the pipes and cushion them, allowing for expansion - as you say, then plaster over. Maybe use the low-expansion foam as just skimming over with 2/3mm of plaster leaves this section of wall weak and liable to impact damage. A good depth of bonding plaster over the foam and then a final skim over

    Or wrap the pipes with hair-felt lagging, build up the depth with plasterboard, tape and skim over

    Or ,,,,,,,,,, various options ,,,,,,,, :)

    ASIF HUSSAIN New Member

    Think I'm gonna go down the route of expanding foam and plaster to finish. It's gonna be behind a sofa so no chance of any impact

    1 more question. Am I best of using the expanding foam with the heating on once the pipes have cooled down

    Thanks for all the help so far
  9. tehvlb

    tehvlb Member

    I'm not sure if plaster will take to expanding foam, if it does then bobs your uncle.

    ASIF HUSSAIN New Member

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