We have received a couple of questions about the ridge beam connection detailing. Even though we do not have a final series of blocks for it yet, we thought it might be a good idea to share some work in progress just in case it might be useful to the community.
What is a ridge beam?
It is the beam at the top of the roof. It collects the loads bearing on the roof (e.g. snow), and it transfers them into the side walls supporting it.
Do you need one in your WikiHouse project?
Most likely. We see the ridge beam as the easiest solution. The alternative is to use a tension element (such as a cable, or a timber element) on each couple of roof blocks. This might reduce the liveable space compared to the ridge beam, therefore we think it might be less appealing.
What is the ridge beam made of?
Solid timber is likely to be the easiest solution. It can be either Glulam, Laminated Veneer Lumber or I timber joist. Glulam and LVL offer higher capacity/stiffness than I timber joists, so these last might not be strong/stiff enough for longer spans. There are calculators available online to estimate the likely cost of a solid beam, such for example this on here Glulam Beam Price Calculator
What about the dimensions?
It depends on the size of the roof and the span that the beam has to cover.Talk to your structural engineer about it. This is actually bread and butter for her/him.
How does the ridge beam connect to the WikiHouse wall?
There are probably different ways of doing this. A possible solution is to create a sitting bracket for the ridge beam to sit on. It also would be good to provide a connection (for example by using a small plate with screws) that prevents the ridge beam from uplifting and sliding. This is necessary because wind loads will try to uplift your roof, and we should secure that.
3D models of the sketches available here Ridge beam – Google Drive
Hope this might help.