I have a patio roof that I have torn down and will redo as I needed to replace the posts due to rot. I have replaced them with pressure-treated 90x90mm posts but noticed after taking down the old construction that where the rafters were mounted on the wall, it is a very "wobbly" and insecure construction. It is a window wall that for some reason doesn't seem to be anchored at the top, which makes it sway when you close the patio door hard. I will address this when I replace the windows and patio door in the future. But I am considering a simpler solution for the patio roof that would mean I wouldn't have to tear it down when I demolish that window wall.
What I thought of doing was to place a glulam beam above the window section and the patio door, which is about 5.5-5.6 meters in width. But what thickness is required for the posts on the outer edge and the thickness of the glulam beam to be able to support the roof as before? The roof will be metal instead of polycarbonate, but it's probably the snow load you should consider since the roof itself is not that heavy.
Attached are pictures where I have marked in red where I plan to have the glulam beam and the two 90x90 posts that are there now. Can I manage with 90x90, or does something else need to be there?
The posts on the side and at the front are, of course, not yet cut to the correct length
The depth of the roof is 4m, the posts are standard pressure-treated 95x95 uncertain if they are strength-classified, but of course, they can be replaced if needed
The glulam beam needs to be at least 90x405 mm. If you choose a thicker beam, you can instead take a 140x360 mm. The posts, which are 95x95 of pressure-treated wood, are sufficient (but barely) if they meet at least class C 24. C 14 is too poor. Ideally, I would like you to replace them with 90x90 glulam posts. It's the beam's long span and the high snow load values in Gävleborg that cause the issue.
justusandersson, you seem to have an eye for this. I was initially thinking of using pressure-treated beams at the front where there are 3 posts towards the lawn, but since they only come in 5.2m and I need 5.5m to have a single beam there, I also thought about using a glulam beam at the front instead of 2 split pressure-treated ones.
What size might I need for it when there is a middle post not against the wall? The wall is now glulam posts 90x90 on either side of the windows anchored to the wall, as well as a glulam beam 90x405 anchored to the posts and the wall.
For example, could one manage with 42x180 or 56x225 out there? I prefer the beam to be as low as possible, otherwise, I'll bump my head on it if we go out that way.
