Spliced roof rafters

This home is new construction with tile roof. The roof rafters are 2x8 on 16" centers with 2x10 ridges. Several roof rafters have been spliced in a ‘v’ pattern near the roof ridge; several have a plywood scab brace on the side, but several do not.


     \
      \                rafter splice - 
      /                forgive the crude 'drawing'
     /

Will post pic’, but it is hard to see.

100_4861a (Small).jpg

Ridge boards are also spliced in a similar manner. If the rafter has a to span a long distance they have to splice it sometimes. I dont like the installation of the purlin. Its looks like it was laid on its side instead of the trailing edge and should be the same size as the rafter its supporting.

From my understanding Some areas may required engineer to design the splice. Im interested to see others replies to this post. The best place to make ths splice in my opinion would be over a support (purlin)

I was curious too. The splice was in a ‘v’ pattern. Some had plywood nailed on the side of the rafter to strengthen; others didn’t. The construction was heavier than most, 2x8 and 2x10, but the roof was tile, too. The builder is an independent, not the average neighborhood.

It’s hard to understand the whole roof framing system (if there is one) from the photograph. Generally speaking, rafters cannot be spliced. That single 2x4 is not exactly enough to function as a beam. If I were an inspector, I might write something like “Roof framing is unorthodox, and an architect or structural engineer should be consulted to verify its adequacy”:

Linda, you may have to resummit the post. For some reason post under some catagories get less hits than others. Usually newer post do better.
Good luck

James L.

often if a rafter needs to be spliced because the length is too long for a single full span, then it would be doubled-up. that would be the cautious way to do it in the field.
it was not designed by a professional to be built like this. consulting a structural engineer (not an architect) would be advisable.

Sorry, but there is no reasonable way to splice a rafter and still maintain structural integrity. and this is something every architect should know. Very long rafters require premium extra-length lumber, or intermediate supports. otherwise a truss should be used.

Richard Hetzel is correct.

There is no reasonable way to splice rafters and splicing rafters constitutes a serious building code violation.

Not only should any structural engineer or architect know this, so too, should every builder and code official.

Could you tell us about this code that its violating? I would like to know so I can reference it.

Thank you

Since Texas uses the International Residential Code in most jurisdications, you can view Chapter 8 of the 2000 through 2006 versions of that Code to help you understand proper rafter construction techniques.

But I’ll give you a hint:

Try section R802.6 of the 2003 IRC or 2006 IRC:

Unless each end of the ‘splices’ of rafters are supported at the ‘splices’ (as Richard Hetzel rightly stated a few posts back) by a structural support at least 1 1/2" wide under each end… these ends ‘spliced by plywood’ do not structurally* ‘bear’* on anything…only ***‘air’***…and therefore do not meet code minimums…

Therefore, the rafters illustrated in the photos above… violate IRC Code… and remain illegal under any circumstance where the IRC is employed.

When I was working in Florida as a roofer when a reroof was pending, existing shingle and new to be cement tiles there would be engineering and modifications done to bear the new roof loads.

James is right, that type of splice is typically used for ridges, and it’s a very sophisticated, strong splice if done correctly… for ridges. This is not a great framing job. I’d recommend a contractor evaluation, and as a contractor I’d add a plywood gusset to any rafter spliced like that. I’d gusset both sides, use glue and a lot of nails. It’s probably OK… but maybe not and who carries the liability if it’s not?

The purlin is badly done and should have been a 2x6 on edge square to the roof pitch if possible. The flat 2x4 is ineffective for most of the distance between braces.

homebild, thanks. Interesting point of view but it doesnt really say that you cant splice it. Its similar to the code saying that the roof decking should be solidly decked. I am not saying your wrong and it definetely is a poor framing job. Like I said earlier an engineer may be required not only due to the splice but the actual purlin being installed incorrectly (if indeed its a purlin, which it does appear to be) and providing inadequate support. If it was my call I would be calling out for further evaluation.

A “purlin” is a secondary member that spans between primary roof framing members such as trusses. A purlin is not a support for trusses or rafters. Such a support is called a “beam” or a “girder”. The 2x4 in the picture has a lot of growing to do before it can assume either of those names. A 2x6 would barely be any better. Since there is a rafter splice, the rafters are structurally compromised, and must be properly supported under the splice by a beam or girder which is designed to carry the loads of the roof to points in the structure below, where such loads have a direct path to the earth. I’d expect to see something like a pretty beefy double LVL where that 2x4 is, but without knowing the exact roof load nor the span of the girder, that’s all that can be said. The roof framing is improper, and requires evaluation by an architect or structural engineer.

Absolutely wrong. A truss roof never has a purlin assembly and a purlin assembly is designed to cut rafter spans and brace down to the tops of walls. Rafters do rest on purlins. I don’t know how you define “secondary member”, but what you’re descibing is known to us master carpenters as a “block”.
Girders are framing members installed under floor framng. There are also members called girders which are part of a truss roof assembly.

Odds are good that any competent framing contractor could not only evaluate but correct this little problem for what you’d have your client pay just to have an engineer look at it.

Absolutely positively wrong. There are primary framing members in a roof. They could be rafters, trusses, or any other kind of structure, such as in steel buildings. Sometimes, especially in commercial buildings, they are widely spaced, perhaps in the order of 25 feet in steel structures. Obviously no decking can span that distance. So, in that case, secondary framing members are introduced, running perpendicular to the primary members, and these are called purlins. Purlins reduce the spans required for decking. When repetitive primary members such as rafters or trusses need intermediate support, a girder is introduced. The definition of girder is a beam which supports several other members. Rafters, joists, and girders are all beams. Any structural member which spans a distance is a beam.

It would be the rare master carpenter who could calculate the loads on a structure and design beams or girders to support those loads. With the splice in the rafters, a girder is necessary to carry the two end loads of the rafter sections. That 2x4 on the flat isn’t even close to enough to do so. If there is a load-bearing wall directly beneath the splices, then a row of studs with spacing no greater than the rafter spacing could carry the loads, but then, a double top plate would be normal. And that is provided that the roof load was designed into whatever supports the load-bearing wall at the lowest level. If the original rafter design did not call for the splice, then the structure below was probably not designed to take roof load at that location.

See why an architect or structural engineer is needed?

I think he meant a purlin is not used on roof trusses. Which I have not personally ever seen.

We’re in general agreeance here except that I would say the purlin cuts the span of the rafters. I was saying a purlin doesn’t go between framing members as per your post

In my experiance a purlin runs benearth rafters, not between them. My background is in residential carpentry in CA and CO and I went through the 4-year apprenticeship program. What’s pictured there is what I’ve always heard called a purlin system. When you start talking to people with different backgrounds (as in commercial building orengineering) you start seeing confusion about terms. I think that’s what we have happening here. To a residential carpenter, rafters, joists, girders and beams have specific meanings. I think we’re mixing carpentry and enginering terms here Richard, I’ll bet your background is as an engineer. :slight_smile:

I don’t think carpenters should do engineering. From past experience I’d feel comfortable as a contractor using gussets to support this spice. I just don’t see it as that serious an issue as long as that splice is done correctly and there are no special loads like mechanical equipment above.

I originally found that splice illustrated in Architectural Graphic Standards, which, when this splice is used in a ridge, does not recommend placing a post directly beneath the splice, as this loads the splice, but moving the post over so that bending forces will be neutral at the location of the splice. whew!

Yes, that’s what I meant.