Hi!
I'm considering renovating half of the attic.
The house is half-timbered and the rafters have varying centers between 1000-1300. And of course, they're not perfectly aligned. My question is whether I should hire a structural engineer to check if the rafters can support the additional weight that plasterboard entails.
My initial thought is to "hang" a 45x145 or similar on the existing rafter and use a string to get them reasonably aligned. Then attach 45x45 and plasterboard. Ventilation and insulation too, of course.
I was thinking of using cellulose insulation, and they claim that no ventilation is needed, but it sounds uncertain to me.
Is there any point in providing these new rafters with braces and collar ties? I'd prefer to skip the collar ties since it looks awful with double collar ties when it's finished.
To clarify, I'm wondering
1. Is a structural engineer needed to ensure the roof can handle the extra weight, especially of the plasterboard?
2. Do the new "rafters" need to be anchored in any way other than just screwing them into the old rafters?
3. Can someone knowledgeable confirm that cellulose insulation doesn't need ventilation?
All the best!
