ᐅ Repointing Sand-Lime Bricks – Which Mortar to Use?

Created on: 17 Feb 2021 20:23
S
South
South17 Feb 2021 20:23
Hello dear community,

we have purchased a rural farmhouse from 1904 and are currently renovating/modernizing parts of it, including the exterior mortar joints. Some of these need to be replaced, depending on the wall’s orientation and the weather exposure. Our mortar specialist suggested using quick-mix (cement mortar).
This does not necessarily have to cause problems, but with old solid bricks, likely field-fired bricks, there is an increased risk that either the joints will crumble again or even the bricks themselves might be damaged due to differing strength and moisture absorption.

I have done some research and identified lime mortar alternatives, such as air lime/ shell lime and pozzolanic lime mortar, for example gräfix 55 coarse, as better options. Spontaneously, I would prefer the latter since it is ready mixed and costs about 9.00 EUR per 30 kg (66 lb) bag, which should yield around 20 liters (5 gallons) of mortar.

Does anyone have experience with this?
I will try to get in touch with the architect tomorrow, although that has been somewhat difficult lately.
N
Nordlys
17 Feb 2021 20:51
Yes, I have experience with historic buildings. Your suspicion is correct, lime mortar is softer—use that instead of quick-dry mix.
South19 Feb 2021 09:23
Thank you for the response. Would hydraulic lime mortar be an option? It seems opinions on this vary quite a bit. Solubel was also recommended to me, but there is no supplier within a radius of 150 km (93 miles), so I doubt I can find a plasterer who works with this product. For example, our plasterer was not keen on shell limestone mortar, saying it was too complicated.
N
Nordlys
19 Feb 2021 10:49
Trass makes mortar waterproof.
Use it.
South22 Feb 2021 21:38
Thank you for your feedback again 🙂