Share
Have a 9cm Diameter Hole from AC removal I am patching today + patching from old screw holes.
Plan is for the interior to fill with Earls Expanding concrete, then UniPro Multipurpose Filler - Sand and Paint.
Was going to apply the same process to the screw holes or it that overkill with the multipurpose filler being sufficient?
How long should I wait after applying the expanding concrete before the filler?
On the outside I was just going to messily shove a brick with some of the expanding concrete in there and then cover with a vent to make neat (see vent below).
Will post progress pics just seeking advice/comments - thankyou
Hi @robjow,
That method sounds like it will work.
For the screw holes, I'd be inclined to just use the multi-purpose filler. With the expanding concrete, by the book, you should wait for it to fully set, which is at least 30 minutes. After that, I'd just fill over it. It cures with a chemical reaction, so you shouldn't experience any issues filling it over by that stage.
The vent on the outside sounds like a reasonable option, or you could use the expanding concrete again and trowel to a smooth finish.
Please let me know if you have any questions.
Mitchell
*Update
So I started filling with the expanding concrete but I found there was so much hole to fill and the concrete kept melting down flat I would have to do it in stages
instead I found a spare brick and crushed it into chucks, i threw the chunks in the hole which gave the cement something to stick to
I left too much gap for the multi-purpose filler not realising you only apply it in 3mm applications - then wait ~ 2 hours to dry - so had to to do about 10 coats of that but it came out perfect, just need to paint! Vent worked well to hide the repair on the outside too
ty all
