I am installing a vapor barrier in the attic and am considering how to handle a specific area.
I have emptied the attic of sawdust and am placing the membrane between the rafters but not wrapping it around and over in this case. I have installed a masonite board with an air gap against the outer roof. The membrane has an sd-value of 18.
At the edge of the ceiling, there is a beam on which the rafters rest, and there is only 15cm out to the masonite, where I think it might get a bit colder than the rest of the structure. There will be 40-45cm of insulation above the ceiling. On the other side of the beam (in the closet with the sloped ceiling), the plan is to lower the ceiling at least 45mm below the beam to increase the insulation.
The question is whether you think I should extend the vapor barrier over the beam and then down the other side?
I see risks with both solutions actually. Without the vapor barrier, more moisture will escape in that area, which is a risk in itself, but the advantage is that it won't be trapped and can be vented out. With the membrane, it will be sealed, but the moisture level in the beam should be higher, and with only 15cm out to the outer roof, I see a risk with that as well.
I have emptied the attic of sawdust and am placing the membrane between the rafters but not wrapping it around and over in this case. I have installed a masonite board with an air gap against the outer roof. The membrane has an sd-value of 18.
At the edge of the ceiling, there is a beam on which the rafters rest, and there is only 15cm out to the masonite, where I think it might get a bit colder than the rest of the structure. There will be 40-45cm of insulation above the ceiling. On the other side of the beam (in the closet with the sloped ceiling), the plan is to lower the ceiling at least 45mm below the beam to increase the insulation.
The question is whether you think I should extend the vapor barrier over the beam and then down the other side?
I see risks with both solutions actually. Without the vapor barrier, more moisture will escape in that area, which is a risk in itself, but the advantage is that it won't be trapped and can be vented out. With the membrane, it will be sealed, but the moisture level in the beam should be higher, and with only 15cm out to the outer roof, I see a risk with that as well.
