I recently went to a newly constructed house that had a header spanning over 17 feet and holding the rafters to the 6 pitch roof. I was surprized that the double 2X10 header with OSB center was designed by an engineer and passed the city inspection. My question is with the dead weight of 20 pounds/sq.ft. of the decking and roofing material, would the doubled 2X10 with a 17 foot span be able to hold the weight? I have looked for header detail in the IRC and Framers references with no avail.
A photo is included.
Personally, after validating that the framing was done in accordance with the design, I would look no farther than the engineer’s certification, for a “plan review” is a dozen light years outside of the scope of a home inspection
It may be regional thing but I have never heard these referred to as “headers” but rather purlins. Very common around here and found in old and new homes. Old homes before the days of trusses this was a common practice and method.Purlin
Purlin, or purline, is a horizontal part of the support system in a roof. Purlins offer support for the load of the roof deck or sheathing. They, in turn, are supported by the main rafters or by the building walls themselves.
The use of purlins instead of closely-placed rafters is common in metal buildings and in wood-framed construction. Before there were trusses, purlins were used to extend the support rafters for greater distances than the rafters alone could support.
Read more: http://www.doityourself.com/stry/purlin-roof#ixzz0zWxypHhe
With Doug on this on this one. Headers are found over a door or window around here.
The purpose of purlins is to reduce the span of the rafters (they basically extend the rafter length by putting the brace at the rafter splice).
The span is probably OK. It’s based on R802.5.1(1). That table will tell you the spans for 10 & 20 lbs/sf dead loads.
What I question is the lack of purlin supports. R802.5.1 says purlins are to be braced by 2x4s not more than 4’ apart, tied to bearing walls.
Unless I saw the plans myself, I’d probably comment about the deviation from traditional building methods and recommend that the client verify the design drawings that specify this structural member and it’s lack of bracing.
It may be that the engineer has designed a beam (not a purlin) because there is no bearing wall to brace to. Was it supported at both ends and did the load transfer all the way to the foundation? (Determining the later would be technically exhaustive and I wouldn’t do all that for a home inspection.)
It’s not an ordinary, everyday purlin. It’s a site constructed beam. Notice that it’s supported on 5 studs at the end (probably no load bearing wall below to support a purlin).
I’m with James on this. If it’s an engineered structure and done in accordance with plan, I would only comment if I saw some sign of distress.
BTW: is the roof pitch change over the beam intentional? No rotation?
The term “lintel” had been historically used for load transferring framing over windows and doors. “Header” had been used for load transferring framing around openings in floor joist and rafter systems. Due to the constant and persisitent use of “header” for over windows and doors, in the last 10-15 years, header is now being accepted by many authorities.
True that Brian. Now that you mention it I remembered working for a modular home company years ago and remember seeing header being used on some of the floor drawings. I just thought we had imported Yankee engineers at the time 
That’s not really a “header”. Headers are installed above door and window openings to carry the load normally carried by the studs.
That’s just a structural, built-up beam that’s part of the roof system. If it’s a relatively new home, it would have been approved by an engineer unless the home was built without a permit.
As long as it’s sized adequately, and passes the load to the foundation via a proper path… no problem.
It is strange that it has plywood sandwiched in the middle. That’s usually done when building headers so that the header is the same width as a wall built using 2x4 studs. The plywood is only 8’ long at the most, so it really doesn’t add much strength to the header. Almost as if the framer did it out of habit.
You don’t have to approve the engineering, just comment on signs of failure if you find them.