How to patch missing mortar around letterbox?

heffa

I need to replace/patch the mortar gaps on either side of this letterbox. The frames are solidly bedded in, so it's just patching for cosmetics and weather protection.

My plan is to clean out all the loose debris, then cut some strips of plywood the same width and height as the gaps and wedge them in from the inside, giving a surface to bond onto. Then take either Mortafil or No More Gaps Bricks & Mortar and fill in the surface from the outside.

Does this sound like a good approach? Or is there a better method?

MitchellMc

Welcome to the Bunnings WOrkshop community @heffa. It's sensational to have you join us and many thanks for your question on mortar filling.

That approach sounds like it would work well, especially using the backing to give the filler something to grab onto and fill the void. For a cosmetic/weather seal job, that’s a pretty practical solution.

The other option is to skip the backing and just pack the whole gap with mortar (DIY mix with water). That’ll give you a more solid, traditional repair.

Quick tip for finishing: once the mortar starts to firm up, lightly spritz it with water and then smooth it off (sponge or trowel). You’ll get a much cleaner, more professional-looking finish that blends in better with the existing mortar. Also, it's best to tape up the face of the letterbox to prevent getting mortar on it. It can get a bit messy and saves additional cleanup.

Either way, you’re on the right track.

Please let me know if you have any questions.

Mitchell