ᐅ Insulation of a pitched roof when an additional insulation layer above the rafters already exists
Created on: 10 Jul 2019 20:49
A
AndreMiHello everyone.
I have the following question. A few years ago, we bought a prefabricated house. It has a ground floor and an upper floor used as living space. Above that is the pitched roof, which has about standing height.
The insulation is currently installed on the ceiling of the upper floor. The attic space above is not insulated and only has a membrane under the roof tiles (presumably for vapor protection). I now want to lay OSB boards in the attic. For this, I plan to create battens beneath the boards to allow air circulation near the insulation.
While examining the insulation setup, I found the following: The ceiling of the upper floor is drywall, above that is a vapor barrier (I assume this because it is a metal-coated paper), and on top lies the insulation wool. Now my question is whether I can insulate the attic space and, if so, what the construction would look like—specifically how to connect to the vapor barrier. Do I need to open the roof insulation and vapor barrier and fold it upwards?
I hope my explanation is clear.
Thank you very much in advance for your answers.
I have the following question. A few years ago, we bought a prefabricated house. It has a ground floor and an upper floor used as living space. Above that is the pitched roof, which has about standing height.
The insulation is currently installed on the ceiling of the upper floor. The attic space above is not insulated and only has a membrane under the roof tiles (presumably for vapor protection). I now want to lay OSB boards in the attic. For this, I plan to create battens beneath the boards to allow air circulation near the insulation.
While examining the insulation setup, I found the following: The ceiling of the upper floor is drywall, above that is a vapor barrier (I assume this because it is a metal-coated paper), and on top lies the insulation wool. Now my question is whether I can insulate the attic space and, if so, what the construction would look like—specifically how to connect to the vapor barrier. Do I need to open the roof insulation and vapor barrier and fold it upwards?
I hope my explanation is clear.
Thank you very much in advance for your answers.
G
garfunkel12 Jul 2019 18:32It makes sense that you want to install the OSB boards with a gap to the insulation. However, I would still leave some larger gaps between the boards to ensure proper air circulation.
I consider your plan to be risky. The attic would be insulated but remain unheated. Sealed all around with a membrane, meaning no air circulation. Naturally, the air will stagnate there and will very likely cause problems at some point. You would need to keep it open to the upper floor, but I would think carefully before opening an existing insulation layer. From what you describe, it also seems quite easy to renew or upgrade the insulation if needed. It’s something I would keep as an option.
Is the additional storage space the main goal?
I consider your plan to be risky. The attic would be insulated but remain unheated. Sealed all around with a membrane, meaning no air circulation. Naturally, the air will stagnate there and will very likely cause problems at some point. You would need to keep it open to the upper floor, but I would think carefully before opening an existing insulation layer. From what you describe, it also seems quite easy to renew or upgrade the insulation if needed. It’s something I would keep as an option.
Is the additional storage space the main goal?
Hello Garfunkel.
Yes, that's correct. Additional storage space is to be created. Currently, the attic is hot in the summer and not frost-free in the winter. Anything stored there becomes damp and moist.
I should also add that there are three ventilation holes on each gable wall for attic ventilation. If I insulate the attic, I would probably have to close these as well.
Yes, that's correct. Additional storage space is to be created. Currently, the attic is hot in the summer and not frost-free in the winter. Anything stored there becomes damp and moist.
I should also add that there are three ventilation holes on each gable wall for attic ventilation. If I insulate the attic, I would probably have to close these as well.
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