Masonry foundation A for slurrying before plastering?

[BiFuel]

I am going to plaster a leca wall for a greenhouse and read that you should use Masonry Primer A before plastering with mortar B. It seems a bit overkill for me to apply several mm with the A compound... can I mix it more like porridge and just brush it on with a lime brush? Then proceed with 5-10 mm of masonry and plaster mortar B?

 

[Claes Sörmland]

Yes!

 

[BiFuel]

My father-in-law claimed that it was enough to do the same with regular plaster mix B, but as usual, I got anxious and thought that the masonry base had to be better. Then I became uncertain again... as usual.

 

[neo11]

A mortar is generally used at ground level as a plinth.
But it also functions as a thin priming mortar.
So, as mentioned above, apply a thin layer.
Then parge and plaster with b mortar.
If there is a cap on the wall, c mortar might work better, but I'm not familiar with your project.

 

[BiFuel]

A cement is generally used down at the ground as a base.
But it also works as a thin grounding cement.
So, as mentioned above, thin wash.
And then stock and plaster with B cement.
If there is a cap on the wall, C cement might have worked better, but I'm not familiar with your project.

I'm not entirely sure what you mean by a cap on the wall... I have laid 3 rows with leca blocks, and then a greenhouse will be placed on it (kit, aluminum).

 

[Claes Sörmland]

I'm not entirely sure what you mean by lid on the wall... I have laid 3 layers with leca, then a greenhouse will be placed on it (kit, aluminum).

It sounds like an exposed construction, which suggests using A-bruk for the thin surface foundation.

The safest option is to have a metal roof extending over the masonry with the plaster. If water finds its way behind the plaster, it can easily be frost-blasted.

 

[BiFuel]

It sounds like an exposed construction, which suggests using A-grade for the thin grounding.

The safest way is to have a metal roof that extends over the masonry with the plaster. If water gets in behind the plaster, it will be easily frostbitten.

Yes, it will probably be quite exposed. The greenhouse has an aluminum strip that is supposed to cover the top part of the plaster, but there is a risk that it might not cover it completely.

 

[neo11]

3 layers with leca means that the walling is about 60 cm high?.
Base with a mortar and plaster with b mortar.
As written above, water cannot seep into the stone from above and behind.
Then it will eventually freeze and break apart.
If you have that, you should skip the b mortar and only use cement mortar A, so it lasts longer.

 

[BiFuel]

3 shifts with leca means that the masonry is about 60 cm high?.
Base with a mortar and plaster with b mortar.
As written above, water cannot run down into the stone from above and behind.
Then it eventually freezes and breaks.
If you have that, you should skip the b mortar and only use cement mortar A, then it lasts longer.

Yes, 60 cm. I'll see how it goes when we have the frame on top. If it looks like a water risk, I'll try to find a suitable sheet to place there.

 

[BiFuel]

It sounds like an exposed construction, which suggests using A-bruk for thin grounding.

The safest option is to have a sheet metal roof that extends over the masonry with the plaster. If water gets behind the plaster, it can easily cause frost damage.

At the back, I will refill to reach the original ground level. Can I apply a slurry twice and then place a platon mat against the wall before refilling? It feels unnecessary to plaster where it won't be visible. If so, how much time between applications of the slurry?

 

[Claes Sörmland]

At the back, I will refill to reach the original ground level. Can I apply plaster 2 times and then place a Platon mat against the wall before refilling? It seems unnecessary to plaster where it won't be visible. If so, how much time between the plastering sessions?

5 hours?