How to patch hole in Besser block wall?

[notaz]

Hi all, seeing what would be the best method to fill in this hole in my besser block wall where the old gas heater was? The top hole is 30cm x 40cm x 8cm and the bottom one is about 15cm x 15xm x 8cm.

[EricL]

Hello @notaz 

Welcome to the Bunnings Workshop community. It's sensational to have you join us, and thanks for sharing your question about your Besser block wall.

I propose filling the hole with Brighton Masonry 200 x 100 x 50mm Charcoal Mypave 215 Paver as close as possible to the front level of the wall making sure to leave enough space for rendering. I suggest using Dingo 10kg Mortar Mix to keep the pavers together. You can fill the incidental holes with mortar if the pavers are not able to cover the unusual shape of the Besser block hole. Allow the mortar to cure to full strength, I then suggest rendering the surface with Dunlop 20kg Multipurpose Acrylic Render.

As for the smaller hole I suggest spraying the space with Parfix 340g Expanding Foam Filler. Your goal is to fill the space just enough so that you can render its surface. The foam can be cut and sanded down if necessary. My best advice is to make sure to give the foam enough time to cure to reach maximum hardness before you render over it. 

Let me call on our experienced members @Dave-1 and @Nailbag for their recommendations.

If you need further assistance, please let us know.

Eric

[Nailbag]

Hi @notaz 

Its a bit hard to tell for surer, but if the depth of the cavity is only around 40mm or so I reckon you could get away applying 3-4 layers at a time (allowing drying time in-between of a pre-mixed mortar.

@EricL suggestion of filling the main hole with a paver is also a great idea. You would need to square off the opening though with an angle grinder fitted with a diamond blade to cut the open inline with the paver size. The paver also needs to be thinner than the depth of the opening. Fasten the paver using landscaping liquid nails.

Nailbag

[Dave-1]

Good Morning @notaz 

I really liek @EricL's suggestion to fill most of teh space with a paver and then fill around with teh mortar mix. Pretty much like doing a large outside plaster patch I would love to see the photos as you step through @EricL's instructions as this type of repair is one that pops up every now and then. 

I also like the idea of a hardened foam over the waterpipe section instead of just filling the space with only mortar.

Dave