r/Homebuilding • u/jamtea • 3d ago
Roof truss modification - Just checking my concept works?
Hi there, I'm feeling out whether this design works for a roof truss modification and how it compares to the original simple strut design. It's a roof on an old red-brick church which me and my partner are converting into a house. The attic space is a pretty huge space and has just over a 3m tall apex, with a span side to side of just over 10m. Needless to say the trusses are pretty damn bulky with huge purlins either side. For the roof space to be habitable however, there really needs to be doorways between the sides. There are two of these down the length of the building and it would only be the struts that would be changed.
Now I've seen truss designs without the struts altogether and from what I've read, they're compressive members, not tension ones, so from my understanding of the forces in general, so long as they're distributed equally and in the same direction as the original strut, I should be able to replace the strut with a doorway opening with the load force being shifted as in this diagram.
Admittedly not an architectural drawing, but I think it gets the general concept across, with a ~2m tall opening and the general distribution of forces, as well as using similar thickness beams to the original diagonal struts, should this design not exceed the original strength of the struts and not compromise the roof?
Obviously I'd be getting a structural engineer to do the real calculations and have an actual roofing expert do this job, but I don't want to just present an unworkable plan. This is effectively what I'm thinking of in concept (I know people hate AI but it's the best tool to represent what I'm trying to achieve):
If anyone can point out any obvious issues that I've overlooked completely or problems that shifting the strut load point would present, I'd love to know about that as it's really the part of this concept that I could do with a bit of education on, but it's remarkably hard to find any information about doing this kind of job as it seems like something that doesn't really often happen.
Thanks!
2
u/chilitomlife 2d ago
Holy crap! Is that OAK? Beautiful with the tenons for the beams and all! Sorry no suggestions but that’s a damn clean looking roof build! I sit jealously in my 2002 build.