ᐅ Roof insulation of a one-and-a-half-story detached house built in 1964 using mineral wool
Created on: 16 Oct 2023 12:37
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patrick8549P
patrick854916 Oct 2023 12:37Hello everyone,
I’m new here and took over a house built in 1964 just over a year ago. The house has now been gutted, and I can start the reconstruction.
My first question in this forum concerns roof insulation.
The house did not have a solid ceiling between the upper floor and the attic. There were only loose wooden battens between the rafters, with a very thin layer of insulation on top. The ceiling, including the loosely laid battens, has been removed. Beneath was a ceiling made of bamboo mats covered with gypsum plaster—apparently the standard construction technique in 1964.
In the attic, the previous owners had loosely installed insulation wool—a mixture of various types of insulation material. All of this has now been removed, and a walkable floor made of 18mm (0.7 inch) OSB boards has been installed on the rafters. Now the attic can be safely accessed without concern.
So here is my question:
Since the attic height is about 1.20 meters (4 feet) with a very shallow roof pitch, I want to install 120mm (5 inches) insulation between the rafters in the attic. The usable depth of the rafters is 150mm (6 inches). This leaves about 30mm (1 inch) between the battens and insulation for air circulation. On top of the OSB boards, additional insulation boards will be installed because the floor is not going to be used as living space anyway.
In the living area of the upper floor, I want to increase the thickness of the rafters so that 200mm (8 inches) insulation can be fitted between them. Above this, there will, of course, be a vapor barrier followed by drywall panels.
The space between the installed OSB boards in the attic and the drywall will be used for electrical wiring. I don’t plan to install a vapor barrier in this area because the OSB boards themselves will act as the vapor barrier, and the joints will be taped.
The insulation material will be Rockwool Klemmrock. From your experience, does this setup make sense, or am I risking problems with the dew point?
Best regards
I’m new here and took over a house built in 1964 just over a year ago. The house has now been gutted, and I can start the reconstruction.
My first question in this forum concerns roof insulation.
The house did not have a solid ceiling between the upper floor and the attic. There were only loose wooden battens between the rafters, with a very thin layer of insulation on top. The ceiling, including the loosely laid battens, has been removed. Beneath was a ceiling made of bamboo mats covered with gypsum plaster—apparently the standard construction technique in 1964.
In the attic, the previous owners had loosely installed insulation wool—a mixture of various types of insulation material. All of this has now been removed, and a walkable floor made of 18mm (0.7 inch) OSB boards has been installed on the rafters. Now the attic can be safely accessed without concern.
So here is my question:
Since the attic height is about 1.20 meters (4 feet) with a very shallow roof pitch, I want to install 120mm (5 inches) insulation between the rafters in the attic. The usable depth of the rafters is 150mm (6 inches). This leaves about 30mm (1 inch) between the battens and insulation for air circulation. On top of the OSB boards, additional insulation boards will be installed because the floor is not going to be used as living space anyway.
In the living area of the upper floor, I want to increase the thickness of the rafters so that 200mm (8 inches) insulation can be fitted between them. Above this, there will, of course, be a vapor barrier followed by drywall panels.
The space between the installed OSB boards in the attic and the drywall will be used for electrical wiring. I don’t plan to install a vapor barrier in this area because the OSB boards themselves will act as the vapor barrier, and the joints will be taped.
The insulation material will be Rockwool Klemmrock. From your experience, does this setup make sense, or am I risking problems with the dew point?
Best regards
It’s best if you take some photos and make a drawing of your project. By the way, I have a fresh reading recommendation for you from today: https://www.hausbau-forum.de/threads/spitzboden-rauspund-auslegen-tipps.46229/
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https://www.linkedin.com/company/bauen-jetzt/
https://www.instagram.com/11antgmxde/
https://www.linkedin.com/company/bauen-jetzt/
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patrick854916 Oct 2023 21:13I have already read several threads on this topic. The question is whether it even makes sense to install 120mm (4.7 inches) of insulation between the rafters in the attic if there will be insulation applied on top of the OSB boards anyway. Basically, only a service hatch without a ladder will be installed at the end since the attic space is otherwise unusable.
Since the OSB boards are already installed, I am not going to change that. They also provided the horizontal rafters with good stability, as they were previously only notched and partly unstable. I would then connect the vapor barrier from the sloped roof sections to the OSB boards.
Since the OSB boards are already installed, I am not going to change that. They also provided the horizontal rafters with good stability, as they were previously only notched and partly unstable. I would then connect the vapor barrier from the sloped roof sections to the OSB boards.
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