Hello everyone,
We are renovating our 1950s house (wooden beams, cold roof) mainly by ourselves.
Unfortunately, I followed bad advice and initially installed 16cm (6 inches) of mineral wool as insulation between the rafters without ventilation behind it. As a result, I had to remove everything again, treat mold, and sand the surfaces.
Now a company has redone the entire job. However, another craftsman suggested that it would be better to use a climate membrane instead of a vapor barrier (PE 200).
The assembly from outside to inside is as follows:
Roof tiles on battens
Bitumen membrane (nailed, vapor tight)
1.5cm (0.6 inches) boards (sheathing)
3cm (1.2 inches) air gap
16cm (6 inches) mineral wool with thermal conductivity class 035 (between doubled rafters)
Vapor barrier PE 200 (blue)
Substructure
Gypsum board
According to Ubakus, everything is fine in winter, but there is a risk of moisture in summer.
A master builder working with a well-known insulation manufacturer’s system recommended a climate membrane without question.
Another craftsman said simply: “It’s fine as is.”
Unfortunately, this is also challenging financially. Additionally, I found several mistakes by the company, such as unglued spots at the walls (there were more issues as well). These spots have already been repaired.
Important: On the flat ceiling areas, the vapor barrier was not glued to the walls because, according to my father (a retired bricklayer), “that’s how it was done back then.” However, there have been no problems with this, even after 2 years.
Moisture or mold issues appeared only on the sloped surfaces—where the mineral wool had direct contact with the roof covering and partly on the beams.
At the moment, I see three options:
- Wait until summer and check for moisture in the insulation during muggy weather → possibly claim warranty
- Remove everything again and redo it with a climate membrane
- Repair connections and sealing, then hope it works
Thank you for any advice!
Best regards,
Jakub
We are renovating our 1950s house (wooden beams, cold roof) mainly by ourselves.
Unfortunately, I followed bad advice and initially installed 16cm (6 inches) of mineral wool as insulation between the rafters without ventilation behind it. As a result, I had to remove everything again, treat mold, and sand the surfaces.
Now a company has redone the entire job. However, another craftsman suggested that it would be better to use a climate membrane instead of a vapor barrier (PE 200).
The assembly from outside to inside is as follows:
Roof tiles on battens
Bitumen membrane (nailed, vapor tight)
1.5cm (0.6 inches) boards (sheathing)
3cm (1.2 inches) air gap
16cm (6 inches) mineral wool with thermal conductivity class 035 (between doubled rafters)
Vapor barrier PE 200 (blue)
Substructure
Gypsum board
According to Ubakus, everything is fine in winter, but there is a risk of moisture in summer.
A master builder working with a well-known insulation manufacturer’s system recommended a climate membrane without question.
Another craftsman said simply: “It’s fine as is.”
Unfortunately, this is also challenging financially. Additionally, I found several mistakes by the company, such as unglued spots at the walls (there were more issues as well). These spots have already been repaired.
Important: On the flat ceiling areas, the vapor barrier was not glued to the walls because, according to my father (a retired bricklayer), “that’s how it was done back then.” However, there have been no problems with this, even after 2 years.
Moisture or mold issues appeared only on the sloped surfaces—where the mineral wool had direct contact with the roof covering and partly on the beams.
At the moment, I see three options:
- Wait until summer and check for moisture in the insulation during muggy weather → possibly claim warranty
- Remove everything again and redo it with a climate membrane
- Repair connections and sealing, then hope it works
Thank you for any advice!
Best regards,
Jakub
Similar topics