I am in the process of decorating my upstairs in our Småland villa.
I've been thinking about leaving it open to the ridge in the dormer, but now that I've reached that stage in the construction, I'm a bit uncertain.
In the other sloping roofs, I have 240mm insulation, but if I saddle (or whatever it's called in technical terms) so much, the roof angle will drop so far down the wall in the dormer that it won't match the ceiling height in the rest of the room, I hope you understand what I mean.
Now to my questions.
Is it unwise to have only 200mm in the sloping roof in the dormer, and about 160mm at the ridge since the air gap takes up some space there?
I don't want to risk function, I'd rather close up the ridge and insulate as usual than have it poorly executed.
Here you see what I mean, I would ideally like to have more insulation there, but then I'd have to saddle more, and then the truss comes further down the straight wall.
Here there will only be about 160mm of insulation? doesn't feel right
I have a question about the area marked in this picture, should there also be an air gap there? The air has nowhere to go? But maybe you do it anyway, perhaps the function isn't solely for the air to pass from one side to the other? Please enlighten me, thank you
I hope some carpenter or someone who has done something similar can help me.
Dallelkpg wrote: I have a question about the area marked on this picture, should you also have an air gap there? the air has nowhere to go? but maybe you do it anyway, the function might not only be for the air to pass from one side to the other?
Yes, there should be an air gap connected upwards and downwards so that the air can circulate/ventilate away moisture.
If the ceiling height is not too low, I would build out and lower the sloping wall a bit to fit in 240mm. At the ridge, you can place a "nockbräda," i.e., a board/gypsum strip that gives a few dm wide flat ceiling strip, so it becomes fully insulated everywhere.
Thanks for the response, Oldboy! What would you recommend as a column right there? I don't know if you know what it looks like in an SMV Kalmar from that angle, but it's a bit difficult to get something tight. I've been using hardboard between the rafters and windproof paper at the bottom by the eaves, but I'm not quite sure how to solve this... Any tips? And while we're on the topic of insulation - is there a specific thickness, or are 200-300mm in sloped roofs just recommendations?
Just so I haven't misunderstood:
Is the masonite forming the underlayment, or have you placed it there to act as a backing so that the insulation does not press against the outer roof/boarding?
If the masonite is acting as a backing (so that the insulation does not press against the outer roof/boarding), and there is an air gap between the masonite and the outer roof/boarding, then there should not be an additional air gap in the red-marked area (or anywhere else).
(I don't know how this particular house is constructed, other than what I can discern from the pictures + text.)
Insulation thickness in sloped ceilings is just like any other area, the more the better. Sloped ceilings usually have insulation thickness based on what's practically possible, especially in older houses. It's important to ensure it's properly windproof; otherwise, it doesn't matter how much insulation is added. Remember that masonite expands and contracts a lot, and consequently, gaps can easily form at the joints. So it's not wrong to use insulation with windproof paper against the masonite.
Hello again! I am installing masonite to create an air gap between the insulation and the outer roof (which also consists of masonite boards). I fasten the boards to a 25*50 batten, thus creating a 50 mm gap. The masonite seen in the red-marked area on the picture above constitutes the outer roof. I attach a picture from my own attic... One picture shows the dormer and the area that I don’t know how to resolve (the black rubber mat...). I suspect it's supposed to make it airtight, but how to deal with the air gap right there? The other picture shows the masonite forming the air gap in the other sections, at the bottom I plan to attach windproof paper against the top plate.
Does the rubber mat seal completely against the outside air everywhere?
I would think that the rubber mat is meant to make the underroof tight at the roof angle, i.e., it should go roughly like the corresponding metal angle under the roof tiles? Then there should be an air gap down towards the facade? Additionally, the ventilation is complicated by the slanting supports. Is it possible to drill ventilation holes in them?
If the house is designed to be finished on the upper floor - how does the house/building company do it? Can you call and ask?
