Does header size depend on roof type?

[Alan Gage]

Was doing some research on header sizes and started to wonder if it made a difference depending on roof type.

I realize you can get away with less (or no) header in a gable wall since it carries little load but what happens when you go from a bearing wall on a gable roof to any of the 4 bearing walls on a hip roof? It would seem to me a hip roof would spread the roof load over 4 walls instead of the 2 walls of a gable roof, which means less load per wall.

Am I wrong? Does code allow lighter headers with a hip roof? The only charts I've found make no distinction.

Alan

[MountainDon]

Interesting question Alan. The IRC prescription seems to be based on gable roofs. With a hip roof the longer side walls will be loaded the same as a gable roof would until the area of the end walls are reached. Then the load spreads out to the end wall some. It would be less than the load on the side walls, but how much less? I believe one would use the same header sizes over door and window openings in the end walls as would be used in the side walls. That makes the prescriptive nature of the IRC easy. On the other hand an engineer would be able to calculate more precisely and perhaps reduce header size requirements. Then again the conservative nature of the typical engineer may enter and there might be no difference spec'd.


Side note:  Our home was built from plans that were meant for a tract builder. The windows in the gable end walls have the same size headers as those in the side walls, even though technically they did not require headers. I was told that made it easier for the framing crew to construct walls; make them all the same as far a header sizes so nobody had to think too hard. No real harm done except for a little more material than necessary and the heat bridging, but that was of little concern 25 years ago.

[Don_P]

That is still common, I build that way. If you can use all the same size and length bolt in an assembly there is less chance of a screw up down the line, same theory here.

A header is required in a gable end if supporting more than 2' of wall above. The framing and sheathing can in some cases form the header if you are trying for OVE, I'd have an engineer on board at that point.

[Alan Gage]

M_Don:

I think you're right. The end walls would take some of the load but most of it would still be on side walls. Looks like I'll be keeping the end wall headers nice and beefy. Certainly not worth getting an engineer involved in order to maybe save a couple 2x10s.

I can see the benefit of doing all the headers the same size too, especially if you're doing it for a living.

Thanks for the answers.

Alan

[PEG688]

For all intents and purposes a  on a hip roof all exterior walls are bearing.  Maybe a little less if it 's a truss roof hip with a bearing girder truss, but on a stick frame I'd say the exteriors walls all bear the same.