I am making some changes to an older home … adding a door here, a window there, etc. These outside walls are the bearing walls of the house.
Instead of the usual solid wood header one commonly sees above doors and windows, is it allowed to ‘double up’ pieces of TJI of an overal size equal to the header? For example, to replace a 4×10 header with a pair of 2×10 TJI’s?
I ask for two reasons:
1) It’s easier to cut the thinner TJI’s; and,
2) I can fill the voids with insulation.
So … what say you?
Replies
It's possible to use I-joists as headers. But they're not exactly like 2x lumber, so each header would have to be looked at individually.
If you get it approved by the manufacturer of the I-joists, you're likely to end up with some blocking and web stiffeners. By the time you're done it would have been easier and cheaper just to use 2x lumber.
There are manufacturers who make insulated headers. You might ask around locally about those.
You might want to look into alternatives that involve plywood boxed out to allow insulation. Someone will come along with the link - I lost that link when I changed computers and haven't googled it in a while, but it's from a nationally recognized organization and is probably simpatico with local code officals.
I'm really glad the cache count for this post was increased - for a second I thought my reply may not make it 'cause of the cache limit! lol
Perhaps it's best I explain the plan a little more.
I have an exterior frame wall, a bearing wall, on a single-story house. It is my intent to add to this wall a window and a door.
The existing wall already has one window. I intend to 'skip' over a 16" stud bay, add another window that will fill two stud bays (32" o.c. between the remaining studs; appx 27" rough window opening), skip another stud bay, then add a 32" exterior door (meaning that three stud bays will be affected.) That means a 30" header and a 35" header.
It occurs to me that, especially over the door, I might later desire a way to pass wires over the door ... pairing TJI's would create a chase for those wires.
Naturally, the 'easy' thing for me to do is to simply copy the construction details of the existing windows (which are 36" wid) and the existing doors elsewhere in the house.
Truth is, considering my location - deep in the heart of "flyover country" - it's most likely that I'm going to have to pair up lengths of 2x lumber to make the header. I'm not overly fond of that idea; the sceptic in me suspects such an assembly is weaker than a solid piece of wood. I'm certainly not equipped to plane the 2x's and sandwich a steel plate between them; getting the plate would be as much a challenge as finding anything else around here.
About the only bit of 'grace' I have is that these are rather modest spans.
FWIW, I will also face a similar structural issue when I cut open the floor in one room, to add a crawl-space access. That will mean cutting one, possible two, floor joists. At least, in that instance, I can add supports under the floor.
Plywood box beam will do what you want
http://www.apawood.org --
http://www.apawood.org/level_c.cfm?content=pub_searchresults&pK=panel%20and%20lumber%20beams&pT=Yes&pD=Yes&pF=Yes&pubGroup=plyhttp://www.apawood.org/level_c.cfm?content=pub_searchresults&pK=panel%20and%20lumber%20beams&pT=Yes&pD=Yes&pF=Yes&pubGroup=ply
All you need to know. I know these were addressed in the IRC at one time, don't know if the current edition covers it & I'm too lazy to look.
Joe H
Hmm ... thought I had already replied ...
Joem thanks for the info - and the link. Look like we have a solution!
Link isn't right
It went to this PDF but went missing.
Joe H