I am going to change the floor plan in a house built in 1970. The roof trusses are so-called W-trusses, and my question is whether these are always self-supporting. When the house was built, they clearly put up the trusses, then nailed plywood sheathing on the underside, and then put up interior walls consisting of 70 mm wide studs. This makes me believe that the trusses are self-supporting. However, I removed an interior wall, and then the saw pinched, so the roof probably dropped 1-2 mm. Where I removed that wall, there is an additional interior wall 1.5 m away that will remain, so I am not worried about this. But in another part of the house, I want to open up about 3 m completely without an interior wall, the span is about 8.5 m. Do they ever build with W-trusses assuming they should be supported by interior walls?
The trusses of that type are supposed to be self-supporting, but this assumes, for example, that the attic isn't used as storage. At some point a few decades ago, the snow zones were changed after some roofs collapsed one winter with very heavy snow, which means some trusses are a bit too weak.
If it's some kind of modular or prefab house, it could be different.
Interior walls also have a stabilizing function, i.e., ensuring that the outer walls don’t buckle.
If you want to be sure about removing more walls, you should hire a construction engineer with knowledge of houses from that time.
If it's some kind of modular or prefab house, it could be different.
Interior walls also have a stabilizing function, i.e., ensuring that the outer walls don’t buckle.
If you want to be sure about removing more walls, you should hire a construction engineer with knowledge of houses from that time.