ᐅ Filling Conduit Chases in the Shell Construction Phase – Which Mortar to Use?

Good evening forum members,

We are allowed to seal the conduits in the interior walls ourselves, but it turns out to be not as simple as it seems. If you ask the “www,” you get a wide range of answers. However, whether these are technically correct is often questionable when you think about it more closely.

For the exterior masonry, we sealed the recesses with quick-mix LM5/21 mortar because we have perlite-filled hollow bricks, so the insulation properties were the main priority. We noticed that this mortar shrinks significantly while drying and repeatedly causes cracks. Unfortunately, there was no alternative mortar for us because of the mentioned insulating properties of this lightweight masonry mortar. Now we have looked at all the slot filling mortars on offer. The prices range between 20 and 30 euros per bag. Naturally, we wonder whether these are necessary or if there is a technically equivalent but more affordable alternative.

Our plasterer is unfortunately already on summer vacation and won’t be available until the end of August. We need to be finished before that. What kind of mortar have you used for this? Did your plasterer recommend a specific mortar, or have you received any important tips on this topic? It would be great to get some helpful information here.

Thanks in advance for reading and responding.

There are good reasons to use joint mortar. It also matches the thermal insulation properties of the brick well. It is a bit unusual to mix, but you get used to it.