We have enclosed a veranda that sits on an existing foundation wall from 1929. The veranda has a crawl space, and today I drilled a hole to install a 200x200 mm ventilation grille. The wall is cast with quite sparse cement and full of natural stones.

Naturally, I hit right on a larger stone. Rather than trying to break it, I chose to take a new attempt just beside it. Again stone, but managed to free it after drilling around. Thus, quite a bit more damage to the wall than what the grille covers. The plan is to re-plaster the foundation, but it will take some time as a new staircase needs to be done first. I would like to fill in the hole I started with and build something that looks a bit more like a channel rather than a tank-made hole.

My question to the people is which product I should use to tidy this up. Mortar, and if so, what type? Or some plaster mortar? The thickest repair will be about 70 mm and the thinnest place maybe 10 mm. How would you have done it?

A hole in a stone wall for ventilation with exposed rocks, beside a 200x200 mm metal vent grille being held by a gloved hand.

A rectangular hole in an old concrete and stone wall, discussed for ventilation and repair. Debris is scattered at the base, and uneven edges surround the opening.

Vent hole in an old concrete foundation wall with rough edges, next to a metal vent grill; soil and rubble are visible beneath the wall.
 

Best answer

S
Suffice with some cement mortar, but don't extend completely, then the replastering has something to adhere to.
 
  • Like
Bernieberg
  • Laddar…
It became cement mortar and it worked fine. Applied much more than one should in one go, so it tended to slump, but managed to get something reasonable together in the end. It just needs to be somewhat mammal-proof while we wait to properly fix the foundation.

It could make any mason a little teary-eyed!

A cement wall with a repaired hole and rough cement patching, surrounded by rubble and dirt.

Rough cement wall with newly applied cement patch around a metal vent. Ground below with scattered rocks and soil near a rain downspout.
 
S
To make a long story short, what you've done is perfect :) you'll have to search far to find teary-eyed masons
It's good to have proof of what you've done
 
  • Like
Bernieberg
  • Laddar…
Click here to reply
Vi vill skicka notiser för ämnen du bevakar och händelser som berör dig.