I've talked to many "experts" about how to internally add insulation to my walls, and no one can give a clear answer on what works. However, I feel that I have approached a decision, but a few sleepless nights still remain. I would gladly welcome any opinions.
I currently have an uninsulated brick structure (one brick thick) with thick plaster on the outside and 7 cm of lightweight concrete ("Lecasten") on the inside. I have no idea about the function of the lightweight concrete or if it has been there from the beginning or added over time (the house was built in the 30s, fully renovated in the 60s).
My idea is now to attach 45 cm steel studs with 45 cm foam board on the inside of the lightweight concrete blocks. Then another 45 cm steel studs, offset to avoid thermal bridges, with 45 cm foam board. On this, an OSB or Plywood and then a gypsum board.
If I get condensation between the foam board and the lightweight concrete, no harm should be done since it is not organic material. Or am I making it too easy for myself?
I currently have an uninsulated brick structure (one brick thick) with thick plaster on the outside and 7 cm of lightweight concrete ("Lecasten") on the inside. I have no idea about the function of the lightweight concrete or if it has been there from the beginning or added over time (the house was built in the 30s, fully renovated in the 60s).
My idea is now to attach 45 cm steel studs with 45 cm foam board on the inside of the lightweight concrete blocks. Then another 45 cm steel studs, offset to avoid thermal bridges, with 45 cm foam board. On this, an OSB or Plywood and then a gypsum board.
If I get condensation between the foam board and the lightweight concrete, no harm should be done since it is not organic material. Or am I making it too easy for myself?
I assume you really mean 45 mm!jaso said:
But to the point: I don't think you need to worry about the thermal bridges, but it might be appropriate to have an inner layer of 45 mm to accommodate electrical wiring.
I think you should choose mineral wool instead of cell plastic for insulation. It's not easy to insulate with cell plastic in a framework; you usually need to use foam sealant to ensure the cell plastic seals everywhere.
In areas of the country with heavy rain, you should be cautious with internal insulation of brick structures, but I don't think that risk is significant in your area.
Indeed, I had confused cm and mm :blushing:.
Good point about the difficulty of practically insulating with celloplast between the studs.
The reason for celloplast was mainly its resistance to mold, really. When I tore out the existing additional insulation from the 60s, it wasn't a pretty sight. The previous owner had framed with wooden studs and used glass fiber boards as insulation. The wooden studs were exclusively in top condition, but the glass fiber was almost completely black on the backside in many places. I assume it was mold.
On the other hand, I will now install proper ventilation (FTX), so less humid air should be pushed out into the construction.
Good point about the difficulty of practically insulating with celloplast between the studs.
The reason for celloplast was mainly its resistance to mold, really. When I tore out the existing additional insulation from the 60s, it wasn't a pretty sight. The previous owner had framed with wooden studs and used glass fiber boards as insulation. The wooden studs were exclusively in top condition, but the glass fiber was almost completely black on the backside in many places. I assume it was mold.
On the other hand, I will now install proper ventilation (FTX), so less humid air should be pushed out into the construction.
Don't think the black on the gullfiber is mold, there's nothing for the mold to "eat" on gullfiber. Old gullfiber can usually turn black. I don't know what causes it. You don't need to have two layers with staggered studs, start with a full layer of foam boards (no studs) then use 45 mm studs and place mineral wool in between.
It would be a great relief if it wasn't mold, I must say. The question is just what else it could have been.
Thanks for the idea that one can have a whole layer of cellplast without studs and then add studs on top of it. I hadn't thought of that at all.
Thanks for the idea that one can have a whole layer of cellplast without studs and then add studs on top of it. I hadn't thought of that at all.
The insulation above our ceiling was also thoroughly black in places, but without any moisture - the beams were also completely healthy. It was clear that the insulation was black where there were holes in the plastic, either behind nail holes or poor overlaps. I guess it's dust or soot from smoking that has leaked out...
I have now decided to build the additional insulation as suggested above. That is, 45mm of foam plastic without studs and then a 45mm metal stud wall with mineral wool where the electricity is also routed. Then an OSB and a plasterboard. Whether it was the right decision will be revealed in 10-20 years.
JPW, I think you are absolutely right. It's just a pity that I assumed it was black mold from the start without using my brain...
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JPW, I think you are absolutely right. It's just a pity that I assumed it was black mold from the start without using my brain...
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