Attach lightweight concrete to existing plaster?

[Händige_Helge]

Hello.

We suffered water damage in our turn-of-the-century brick house. It had previously been insulated internally with a stud framework, 90mm insulation, vapor barrier, and drywall. No sill paper = mold in the sill🙄 External additional insulation on the gables, with foam plastic and plaster. Ventilated construction.

Now I have torn down the interior walls and exposed the plastered brick. Instead of a new stud wall, I was thinking of insulating internally with lightweight concrete blocks, to keep the wall "open" and avoid organic material. Then spackle and paint with open paint. What do you think about that?

When I put up the lightweight concrete, can I do it against the old plaster, or does the plaster need to be chipped off so that the lightweight concrete adheres to the brick?

Note! The dark areas on the plaster I don't think are mold. The plaster is sticking fairly well.

Best regards,
/Helge

 

[Händige_Helge]

Hello.

We suffered moisture damage in our turn-of-the-century brick house. It had previously been insulated internally with a stud frame, 90mm insulation, vapor barrier, and drywall. No sill paper = mold in the sill🙄 External additional insulation on the gables, with foam plastic and plaster. Ventilated construction.

Now I have torn down the interior walls and exposed the plastered brick. Instead of a new stud wall, I plan to insulate internally with lightweight concrete blocks to keep the wall "open" and avoid organic material. Then fill and paint with a breathable paint. What do you think about that?

When I put up the lightweight concrete, can I do it against the old plaster, or does all the plaster need to be knocked down so that the lightweight concrete adheres to the brick?

Note! The dark on the plaster I don't think is mold. The plaster adheres fairly well.

Best regards,
/Helge

Does anyone have an opinion on whether lightweight concrete blocks adhere well to plaster?

 

[Anonymiserad 405730]

No one has an opinion on whether aerated concrete blocks adhere well to plaster?

Hi, what is the size of the blocks?

 

[Händige_Helge]

Hello, what size are the blocks?

I haven't decided yet, but maybe 75x400x600🤔

 

[Anonymiserad 405730]

I haven't decided yet, but maybe 75x400x600🤔

Ok, I wouldn't rely solely on gluing these, but you can build them up with thin-set mortar from the floor upwards and then attach wall ties approximately 4 per m2 or even better with a wall anchor..
You drill a plug into the existing wall and then attach a wall tie or screw in the wall anchor that I attached..
In this way, the entire load isn't on the adhesion of the mortar, but the blocks are held in place by both parts..
You can keep the plaster on the wall..

https://www.k-rauta.se/produkt/murkamspik-essve-40x125mm-rostfri-a4-100-pack/7317761041528

https://joma.se/Lemoon/MasterPages/<%= Content.Url() %>

https://www.bauhaus.se/tunnfogsbruk-m10-20kg

 

[Händige_Helge]

Thank you very much! Is it a reasonable solution to replace the previous wooden construction with aerated concrete? I have worked a lot with wood, but never with aerated concrete🤔
The goal is good insulation with a diffusion-open construction.

 

[Karl-Ove Qvarfordt]

Big thanks! Is it a reasonable solution to replace the previous wood construction with aerated concrete? I've worked a lot with wood but never with aerated concrete🤔
The goal is good insulation with a diffusion-open construction.

If you're after good insulation, you might want it a bit thicker than 75 mm.

 

[Anonymiserad 405730]

Thank you very much! Is it a reasonable solution to replace the previous wooden structure with lightweight concrete? I have worked a lot with wood, but never with lightweight concrete🤔
The goal is good insulation with a diffusion-open construction.

I would have placed a tongued and grooved 50mm XPS insulation in between if you want better insulation..

 

[Händige_Helge]

If you're looking for good insulation, you probably want something thicker than 75 mm

Thanks for the input! What's reasonable for good insulation? Previous stud wall was 90 + plaster

 

[Händige_Helge]

I would probably add a tongue and groove 50mm XPS insulation in between if you want better insulation..

Doesn't that ruin the construction if you want to keep it open for moisture transport?

 

[Anonymiserad 405730]

Doesn't that destroy the construction if you want to keep it open for moisture transport?

Can't find anything on that..
But comparing EPS insulation with concrete should come to diffusivity..
So I don't think you need to worry about that..

https://www.sundolitt.com/globalassets/inriver/resources/sundolitt-produktguide-sept-2019.pdf

 

[Händige_Helge]

Can't find anything about it..
But EPS insulation compared to concrete when it comes to diffusion openness..
So I don't think you need to worry about it..

[link]

Thanks! But if you then build up a wall of lättbetong inside the brick wall, how do you finish when you reach the ceiling? Should the wall go all the way up and finish with something like a sill strip against the wooden ceiling, or how do you finish it?

 

[Anonymiserad 405730]

Thanks! But if you then build up a wall of lightweight concrete inside the brick wall, how do you finish when you get to the ceiling? Should the wall go all the way up and be finished with something like sill paper against the wooden ceiling, or how do you finish?

Yes, some form of barrier doesn't hurt..

 

[Anonymiserad 405730]

But EPS or XPS insulation is not a must, you can increase the thickness of the lightweight concrete with..

 

[Händige_Helge]

But EPS or XPS insulation is not a must, you can increase the thickness of the lightweight concrete instead..

Thanks for all your help! What is a "good" thickness for internal insulation? 🤔