If you use an LVL to fill the entire space you are defining, it will be 7" tall, 5 1/2" thick, and 22' long. You will have a different problem... you won't be able to lift it into place without a lot of help or mechanical assistance.
That might be a good reason to build a header.. it can be lifted one piece at a time.
If you build it as a 2x6 box header, it can be insulated. And you won't need TimberLoks- nails will work fine.
SV reX said:In reply to volvoclearinghouse :
I'd verify that with the actual code or from a building official. I think those construction guys are incorrect. I'll bet in MD many people build using 2x6s so they can get more insulation (R-19). But even that isn't required... you are in Climate Zone 4, which means the US Departmwnt of Energy only requires R-13 (2x4)
Ask your building inspector.
I believe the insulation thickness may be the real reason for exterior walls being 2x6. MD has started doing some really strict stuff in the name of energy efficiency. Like, for example, for a roof over an area without an attic, the rafters need to be 10" thick to allow for enough insulation thickness
A 2x6 box header with rigid insulation inside can have an R value of R-19.55. A 6" thick LVL is closer to R-6.
SV reX said:A 2x6 box header with rigid insulation inside can have an R value of R-19.55.
How's that?
In reply to OHSCrifle :
Overall wall thickness = 5.5".
2 layers of 2x6 = 3" @ R-1.1 per inch. Total R-3.3
2.5" of Polyiso @ R-6.5 per inch. Total R-16.25
3.3 + 16.25 = R-19.55
Of course that is only possible where the box is hollow. The top and bottom plates are still solid wood, so a third of the beam is still only R-6, but it's still an improvement. (Average about R-15)
I think that just a double 2x4 Douglas Fir top and tie plate is all that you need for a header @ 24" o.c. spacing. Think of all of the second story floors, walls, and roofs that sit on bearing walls all of the time without worrying about where the studs line up with regards to the floor or roof spacing. Usually, most of the reason you need to place studs at 16" o.c. is because that is the minimum spacing for 1/2 drywall although it sure depends on the loads above. And of course, there are always exceptions. 
All point loads need to be transmitted uninterrupted from roof all of the way down to the footing through studs and or headers.
Make sure to double up the studs next to the window opening.
Strap the second story walls to the first story walls with strapping.
Look up Portal Frame Construction particularly Garage Portal Frame Construction.
Bing.com: continuous garage portal frame detail
jlconline.com: The Portal Frame Option
Got any photos of the proposed work area?
In reply to volvoclearinghouse :
I think I figured out the insulation thing....
I misread the chart a bit. US Department of Energy does allow R-13 wall insulation, but ALSO recommends an additional continuous layer on the exterior of R-10. That make a total of R-23 in your area. That could be done with 2x4's (R-13), but you'd need R-10 continuous on the exterior. That's 2" thick- that's hard to attach siding to.
Alternatively, a 2x6 wall cavity can be R-19 plus R-5 on the exterior. That's only 1" thick- easier to attach siding.
Your local builders choose to use 2x6 because they can meet the energy code easier. But 2x6s are not required for structure.
Sorry for the confusion.
In reply to SV reX :
Or just use R-23 fiberglass insulation.
In reply to VolvoHeretic :
I haven't dug deep into it, but I think the USDofE requires the continuous R-5 on the exterior.
R-23 might work. Not sure.
R-19+ 5 is definitely a better system than R-23 alone.
In reply to VolvoHeretic :
...or 3.5" spray foam in a 2x4 wall. 😉
Where's Frenchy when we need him?? 😂
First of all, I hate polystyrene insulation also known as solid gasoline. Mostly because I don't think that it is cost effective, but also because of that time the owner insisted on holding the floor system in 1" so that the we could place 1" extruded polystyrene board against the outside of the floor trusses only but the plates and walls all where located out at the edge of the concrete basement wall. It was near impossible to layout and square up and very confusing.
Anyway, the full length header is already acting as the top plate so it can be eliminated and the 2x4 can be replaced with 2x6s. Something like this:
Edit: Oops, change STUDS to BOARDS.
SV reX said:Of course that is only possible where the box is hollow. The top and bottom plates are still solid wood, so a third of the beam is still only R-6, but it's still an improvement. (Average about R-15)
That is why I asked.
In reply to SV reX :
Thanks for digging deeper on that. We got down the rabbit hole of structural vs. non structural and I forgot about the insulation requirements.
There's no second story here, so it's just a roof load over this wall. This is a mudroom off the kitchen; it's a simple shed type (single pitch) roof.
Agreed, the big ass beam would be heavy to deal with. I've put 18' 2 x 12 LVL's up on a second floor for my garage by myself, it's not too hard, just tedious. And I do have a front end loader if I really need the help.
I built a different garage (old house) about 15 years ago basically using fitch beams (though I didn't know what they were at the time). I had a 24' span to make and did it with 8', 12', and 16' length 2x12's all sandwiched together, secured with tubes of liquid nails, and screwed. I used a forklift to put them into place. Each beam was 4.5" wide (triple two by 10's). That was fun.
I think a lot of builders just prefer using 2x6's because it makes other stuff easier....like hiding plumbing and wiring. I've built several garages and sheds and have always used 2x6 walls. The structure just "feels" more stable. I know that's not an engineer-y explanation (hey, I'm a Mech-E, not a Civvy) but I have yet to have a structure fall down on me. Having discussed it here, I think I'll go with the 2 x 6 headers.
Concrete guys have been here this week pouring the turn down pad. One fellow has on his company t-shirt...on the bottom of the back it reads: "We may not be the best, but I've yet to find anyone better." I appreciated his truth in advertising.
Also, if it makes a difference, my lumber supplier is quoting spruce, not SYP or Doug Fir. This is a local lumber supplier I've worked with before, they generally have better quality stuff than the Big blue and orange box stores.
In reply to volvoclearinghouse :
2x6 walls are also good for getting more insulation in the walls too besides the extra strength
In reply to volvoclearinghouse :
I enjoy building with 2x6's. Just can't usually justify 150% increase in cost.
Spruce is fine for what you are doing. You might even be able to get 22' long spruce 2x6's
If it was me, I'd probably do a continuous header across the top of a 2x8 on each side and leave the middle open so you can stuff insulation in from the bottom. Really, whatever the fits the height of the window is fine as long as it's above a 2x6. It not for the load though, it will just be easier.
Technically the span is a bit larger than 24" OC since you'd have 22.5"between the studs at 24"OC but you aren't really into scary loads at all and a LVL is overkill
In reply to Antihero :
The span is 24", because that's the window opening. The on-center spacing of the studs would be 25 1/2", which means it would not work for the rafter spacing if they needed to stack.
I'm re-thinking my box bean suggestion.
Since your loads are virtually non-existent, I think I'd build it with 2x6's like this:
That would give you space to insulate after it's built, instead of having to insulate inside the box while you are framing. You wouldn't have to worry about insulation getting wet during the building process. It wouldn't make any difference structurally.
SV reX said:In reply to Antihero :
The span is 24", because that's the window opening. The on-center spacing of the studs would be 25 1/2", which means it would work for the rafter spacing if they needed to stack.
You are right, it was more a pedantic observation for the OP so if he had to describe it that it is a 24 inch span, not 24" OC span.
I may have had a very similar discussion with an engineer once lol. I also had to explain to him that a 4 ft open doorway on a non load bearing wall did not need a 28" x 8 inch aluminum beam and that 2x12s can hold more than 15lbs a running foot at 4 ft
Here is a floor plan and elevation of the wall. With this spacing you wind up with a 36" shear wall on each end of the room. I am assuming these are outside corners? I don't calculate shear walls. I am assuming a standard 8'-1-1/8" wall height. The green studs are laid out at 16" o.c. for sheathing and drywall seams although laying them out at 48" for vertically standing sheathing as long as you also stand your drywall vertically would also work. I would put a stud every 16".
One thing to remember is to not to obsess too much about wall insulation when we are installing how many square feet of glass, one of the greatest conductors of heat there is.
Are we concerned with seismic loading at this location? I have never had to worry about it since ND is the safest earthquake state in the US.
I just realized another thing to watch for with a smaller than typical header...
Depending on the pitch of your roof and the length of the overhang, make sure the rafter tails are high enough for the level soffit to clear the top of the windows.
It would be really bad if you were installing your soffit and found it returned into the glass.
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