How to fix a hole on external wall after electrical box being removed?

[Vincero1]

The Situation

At the bottom of my external wall, there was a poorly positioned electrical box. It was about 10cm x 10cm x 10cm in dimensions and was sitting directly on the paver. This caused moisture to build up, tripping the electrical circuit. The box has been removed, leaving a hole in the wall. The wall is a bit damp, so I’d like to seal and repair it before it causes further damage.

The ask:

I’m hoping to understand the repair process and what product I should use. The location of the hole is directly above ground, so the wall is a bit damp.

 

[JacobZ]

Hi @Vincero1,

I'd suggest using this Polyfilla Exterior Brick and Render Masonry to fill the damaged area. 

Start by tidying up and removing any loose material. Chip off any loos larger bits and give it a clean up with a wire brush.

Once tidy, use a Pro Renovator 100mm Plastic Scraper to apply the filler. Depending on the depth, as the Polyfilla can only be applied in 10 mm-thick layers, you may need to build it up in more than one go.

When you have fully filled the damaged area, use a damp sponge to tidy up and give it a little bit of texture.

When everything is fully dry, paint the repair patch to match the surrounding area.

You might like to check out @Nailbag's handy step-by-step guide on How to repair a rendered wall which uses the same process.

Let me know if you have any further questions.

Jacob

[Vincero1]

Hi @JacobZ,

Thanks for the detailed guide. It’s comprehensive and easy to follow.

I have one question. Since the area was damp because it’s closed to the ground and had an electrical box that trapped moisture, do I need to do anything when  preparing the surface before applying the filler? Or are there any additional steps I need to take to waterproof it?

[JacobZ]

Hi @Vincero1,

I wouldn't worry too much about it being a little bit damp. This could actually be of benefit as it will help the render bond to the surface better.

You could apply a coat of Crommelin Sprayable Exterior Grade Waterproofing to the render before painting over with 2-3 coats of a suitable exterior paint, like Dulux Weathershield to help prevent further water ingress.

Let me know what you think.

Jacob

[AlanM52]

Hi @Vincero1,

Pretty sure you will not have any damp issues once all that material and other build-up is cleaned out and the sun drys that damp area.

Cheers.