Whats the deal with hip roofs

theory2code2practice · Apr 28, 2025

I'm sure this topic comes up quite a lot. I have seen soooooo many hip roofs framed. We all know about the lateral thrust at the corners/lower support if there is nothing holding up the edge of the ridge or if the roof is framed with trusses. So why in the world are these roofs still standing for years? some of them I've seen don't even have hanger for the jack rafters, they are just toe nailed into the end of the ridge beam or an angle. I theorize that the sheathing provides some kind of support. But in theory if nothing hold up the ridge beams then the thrust in jack rafters can be quite high. I've seen older framing books show tension rings around the lower framing, or trusses,..... all this to say.... what's the deal with these hip roofs that are clearly not being structurally analyzed. Thoughts anyone?

TRAK.Structural · Tuesday at 8:59 PM

Ron247 said:
There is another tension tie that is relied on we used to call a "hog trough". It is centered on each span of CJs and we extended it to the wall the hip jacks that were parallel to the ridge sat on. It provided some tension tie ability.

I've seen those a bunch but never knew what they were for, thanks for the insight. Are they typically fastened to each crossing CJ or just to the end walls/hip jacks?

XR250 · Tuesday at 10:12 PM

TRAK.Structural said:
I've seen those a bunch but never knew what they were for, thanks for the insight. Are they typically fastened to each crossing CJ or just to the end walls/hip jacks?

We call them "rat runs" around here. I don't really count on them for anything

Ron247 · Friday at 3:37 PM

The hog troughs are fastened to every CJ and they cut down the unbraced length of the top of the joist and add some vertical load-sharing stiffness so when someone walks over the isolated CJs, they don't cause a ceiling crack. We did connect them to the exterior wall on a hip roof by framing blocking between the short lookout CJs and then nailing into the blocking. While they are not designed as a tension-tie, they serve the purpose to some degree because they go from exterior wall to exterior wall.

gte447f · Friday at 5:43 PM

Ron247 said:
The hog troughs are fastened to every CJ and they cut down the unbraced length of the top of the joist and add some vertical load-sharing stiffness so when someone walks over the isolated CJs, they don't cause a ceiling crack. We did connect them to the exterior wall on a hip roof by framing blocking between the short lookout CJs and then nailing into the blocking. While they are not designed as a tension-tie, they serve the purpose to some degree because they go from exterior wall to exterior wall.

Sadly, modern builders where I am from (American south) would never do this these days, because they ~~couldn't~~ wouldn't spare the cost of a few 2x6's.

XR250 · Friday at 8:47 PM

Many of the incestuous engineers around here will just call out a double rafter on each side of the hip peak in an effort to "brace" it. No connection called out to the ceiling joists or anything. It also does not seem to matter to them if the ceiling joists are perpendicular to the rafters.
I call them incestuous because they all learned it from one particular engineering firm.
The standard of care around here is pretty darn low.

Ron247 · Friday at 10:35 PM

I have seen several where there was no CJ at the last common rafter of the ridge board because it was not part of the normal rafter spacing (24" or 16" oc). Always bothered me.

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Whats the deal with hip roofs

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