Does a ridge board have to be continuous?

[Ron247]

Although I would have never built a roof that did not have the ridge board continuous, I ran into one this week that has about an 18" gap between rafters at one location. EAch side of the gap has a ridge board. I do not see anything in the 2015 IRC that says it must be continuous and they still allow you to build with no ridge board provided you attach rafters to each other with a gusset.

Any thoughts about if this meets code or not? It looks terrible even if it meets code.

 

[KootK]

I see no compelling mechanical reason why a ridge board should need to be continuous. Its primary function is simply that of transferring compression from one rafter to its buddy on the opposite side. There's surely a little bit of a weak axis flexure demand given that rafters are never perfectly aligned but I'd deem that nominal. Obviously, I think that it's good practice to have these things as continuous as possible. A splice every 8' or so wouldn't bother me; a splice every 4' would start to grate.

 

[Ron247]

I think my bigger problem with it the is use of 1/2" cdx or some other sheet material that can sag or bow with time. I see the sags mostly at the end span of the plywood. In older houses when they used no ridge board, the decking was 3/4" lumber which was less prone to sags. Once sags start, the transfer of compression gets less efficient. The lumber was also random length so the need to maintain a routine spacing was not as needed as it is with 4x8 sheets.

They IRC still allows no ridge board at all provided the rafters mate with an "undescribed" gusset.

We always had to splice them but the splices occurred at a rafter. Each ridge board got 3/4" to bear on.

I really find no code requirement in the codes I deal in but was curious if other codes did require continuity.

 

[r13]

I think zig-zag sagging is the primary concern of piecewise ridge boards.