Simple question: Simpson LUC hangers with common rafters?
This should be a super simple question to answer, but I’m just not finding said answer yet.
I will be building a hip roof out of 2×10 rafters. The engineer specified that the common rafters be attached to the ridge beam with Simpson LUC (LUC210Z) hangers. Those are hangers with concealed flanges and a 90 degree perpendicular (non-angled) bottom.
Question: How do I install the rafters with a 4:12 slope in a hanger with a non-angled bottom?
Do I make a little birds-mouth at the top so that part of the rafter lies flat on the hanger bottom? Or do I just place the rafter in the hanger and nail it from the sides but do nothing with the bottom, leaving a 4:12 empty gap between the bottom of the hanger and the rafter (the rafter only touches the edge of the hanger bottom)?
(I know there are LRU hangers that are specifically for rafters, but that’s not what was specified)
Replies
A question to ask the engineer perhaps? They do make hangers designed specifically for rafters as you mentioned, not sure why the engineer did not specify those. Also, you may not even need them. The only time engineers have specified hangers on the ridge for me has been when building a cathedral ceiling where a ridge beam was used. If it’s typical construction with collar ties, purlins, etc you may not need them (but don’t know specifics of your project). I did have an engineer spec joist hangers for rafters as opposed to a rafter hanger once. For that project we made a level cut (but not removing any wood), so basically a notch in the rafter that we slid into the hanger. We found the saw blade thickness enough to allow hanger to fit, but if you are using ultra thin blade it might not allow hanger to slide in.
Okay, good to know. I'll look into the notch option. I supposed I could also call Simpson directly, since they do say that angling up to a certain amount doesn't reduce the load... but then don't show what they mean.
I'll take it, though, that this is just not something that's done very commonly, so maybe it's not a simple question after all...
And, alas, asking the engineer just isn't an option at this point. Communication between us was always very poor but in the end, I essentially had to threaten him to get him to respond at all.
It's not done commonly. Simpson does make adjustable pitch rafter hangers, which I think is a better option than cutting into the end of the rafter. But you really should make peace with the engineer for long enough to verify that as a better option.