Patching awkward hole

shiraz99

I've got this deep hole in the corner of the room under a window sill and was wondering what's the best way to quickly patch and fill it. The walls are solid brick so I don't want to use a gypsum bonding coat and it would be difficult to build up without actually cutting out a bigger section.

Could I just use some foam filler for the bulk of the hole and finish it off with some finishing filler, eh, Toupret or Easifill?

moneysaver1978

I had a similar thing and I used Easifill (or similar) and it worked fine for me.

But... I am not an expert and I do not know what the implications are with that wire.

WIAWSNB

Hi Shiraz.
Is there dampness on the wall surrounding the hole?

shiraz99

WIAWSNB said:

Hi Shiraz.
Is there dampness on the wall surrounding the hole?

Just a bit of condensation, it's a cold spot in that corner with the hole being there right under the window frame.

WIAWSNB

How far up does the void go? Can you see the wall cavity? 

In short, what you propose is fine, but I wouldn't want the foam to travel too far in case it causes a bridge for damp to travel across - tho' very unlikely.

So, personally, I'd first tape over the cable, as far in as the foam will go; it's unlikely to be harmed by the chemicals in the foam, but it's not worth the risk. 

Then, to prevent the foam going in endlessly, I'd aim a few controlled bursts of spray-foam inside the hole but against the sides, so that they stick and form foam lumps. Allow to fully expand and set. Once almost set, you can then add more foam bursts to bridge the remaining gaps until the hole is closed. Or, if there aren't any easy 'sides' you can stick the foam dabs to, you could cobble together a piece of card with a string attached to the centre - push it in to the hole, and then pull it gently back until it stays in the hole in the desired place - spray in against this. Fire a dab against each side, and let it almost fully go off. Then subsequent dabs can be added to close up the hole. 

Allow to set fully, so there's no more movement.

I'd probably want the best part of a half-inch or more of surface recess to be left for applying the general purpose filler, so it'll be nice and solid.  

plumb1_2

The foam will stick better if the area is slightly damp. Spray the foam in about 20mm from the surface. Plus if you have a small spray bottle, spay water on it after you filled the hole it’ll put a skin on it and help it set quicker 
You need a min of 10mm filler otherwise it’ll crack