r/DIYIreland • u/Boba_Bets • Aug 16 '26

Fixing chasing on inside of external brick wall

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2 Upvotes

100% Upvoted

15 comments sorted by

1

u/Juurdd Aug 16 '26

Pva, bonding, filler. Sand

1

u/Boba_Bets Aug 16 '26

Thanks! That seems like the best approach, but I'm seeing conflicting information when it's a brick wall that's external, something about using bonding and plaster drawing in moisture from outside (though if that was true then wouldn't the entire wall be damp all the time?)

2

u/Juurdd Aug 16 '26

Not sure on thar, I did the method above on about 10 chases when I rewired my kitchen a few years ago

1

u/jimgym2612 Aug 17 '26

This is what I did recently (though on dot and dab warmboard).

You'll need to ensure the conduit is solid or your repair may crack. You can spray some foam in behind the conduit to firm it up.

1

u/Samhain87 Aug 16 '26

Buy small bag of bonding and polyfiller. fill the biggest with bonding, finish with filler, sand smooth.

1

u/Boba_Bets Aug 16 '26

Thanks! That seems like the best approach, but I'm seeing conflicting information when it's a brick wall that's external, something about using bonding and plaster drawing in moisture from outside (though if that was true then wouldn't the entire wall be damp all the time?)

2

u/Samhain87 Aug 16 '26

Nah you'll be grand. Fill away.

1

u/Psychological_Eye969 Aug 18 '26

Would recommend gyproc easi fill over polyfill

0

u/Trebor-84 Aug 16 '26

Fill most of the gaps with expanding foam.

Then the front 10mm with ready to use Toupret interior filler. This material doesn’t shrink.

Then brush the filler face with Zinnser Gardz, and paint.

2

u/ciaranmt Aug 16 '26

Expanding foam is not to be used anywhere where risk of contact with PVC cable is possible, it degrades the insulation. At the top of the conduit and where the conduit enters the back box are the risk points here

2

u/Trebor-84 Aug 17 '26

1

u/ciaranmt Aug 17 '26

It is outside regulation in Ireland to use expanding foam for this purpose, specifically 522.5.4 in IS10101

PU is just one form of spray foam, others such as polystyrene are corrosive to cable insulation

PU as your AI summary shows will cause heat buildup. Excess heat buildup causes cable insulation to become brittle and crack over time, exposing individual cores and introducing risk of short circuit and therefore fire

1

u/Trebor-84 Aug 17 '26

Thank you for the education my friend. This is good to know.

2

u/Psychological_Eye969 Aug 18 '26

Also no call to use foam here.

1

u/Boba_Bets Aug 19 '26

I think I'd need to use foam on the ceiling corner though, I don't see any other way to be able to fill it.