Window Header - Full Length of Wall - OK?

I know we have some construction folks here...I have a situation I haven't been able to find an answer for.  We're building a structure that's going to have a lot of windows in the wall.  They will be individual, discrete windows, so we're not looking at having huge spans, just lots of openings.  The wall in question will be 22 feet long.  Each window opening will be 2' wide, with approximately 11" between windows (windows will be evenly spaced in the wall).  So that's 7 windows in that wall.  Rather than making individual headers, jack studs, king studs, etc for each window, I was thinking of doing one long single header across the entire wall, then having each window be essentially just jack studs on either side, with a sill and cripple studs under each one.  

Anyone see any issue with doing it that way?  The wall will be 2x6 studs, and it is load bearing (single story, with a metal shed roof on top of it).  Snow load is mid-Atlantic region.  Plan on doing the header as a tripled- up 2x4, with 1/2" ply strips on each side to make it flush with the 2x6 wall.  

Rough sketch, with only 3 windows as an example:

So, really, it's a series of (7) 24" spans.

Double the jamb studs on both sides of each window, and you'll be fine.

What you're making is called a flitch beam - I suggest putting the plywood between the 2x4s rather than on the outsides.  Spike all the way through from both sides.

Duke said:

So, really, it's a series of (7) 24" spans.

Double the jamb studs on both sides of each window, and you'll be fine.

What you're making is called a flitch beam - I suggest putting the plywood between the 2x4s rather than on the outsides.  Spike all the way through from both sides.

Sounds perfect. Thanks!

As for spiking all the way through, that will be a 5.5" nail. I'm thinking maybe using timber locks or something similar.  

You might want to wrap some strapping up the outside of the opening's stud of the double studs, over the plates, and back down the studs to keep the top plates attached to the studs since there isn't much surface area for OSB wall sheathing and nails to hold everything together. Use 8d sinker nails to attach the strapping.

Don't forget the hurricane clips for your roof joists.

Simpson Strongtie.com: coiledstraps

volvoclearinghouse said:

Duke said:

So, really, it's a series of (7) 24" spans.

Double the jamb studs on both sides of each window, and you'll be fine.

What you're making is called a flitch beam - I suggest putting the plywood between the 2x4s rather than on the outsides.  Spike all the way through from both sides.

Sounds perfect. Thanks!

As for spiking all the way through, that will be a 5.5" nail. I'm thinking maybe using timber locks or something similar.  

Here is the built-up nailing pattern my Structural Engineer had me use. Follow the middle diagram and use 30d common nails and stagger nailing from both sides.

Duke said:

So, really, it's a series of (7) 24" spans.

Double the jamb studs on both sides of each window, and you'll be fine.

What you're making is called a flitch beam - I suggest putting the plywood between the 2x4s rather than on the outsides.  Spike all the way through from both sides.

I did that to keep the 2nd floor above my 22 X 16 living room on the 2nd floor.  Beam the 22ft. way because someone notched the 3X8 joists to put in a bathtub. =~ 0

You may want to think about gluing the thing together also.  Mine was further supported in the basement, just because.

Dan

Glue certainly won't hurt, but it's not necessary.  It's really just a series of consecutive 2-foot spans, which is nothing.  Frankly, half the load on this thing will be lateral rather than vertical, since it's serving to stiffen the top of a very chopped-up wall.

Totally fine to do it that way.

I use a similar thing at the theater to make balconies and larger spans than regular lumber can handle.  The old way of doing it was to make a pony wall with 2x4s and then skin it both sides with 3/4 ply.  That was lighter, but not as strong.

What's your plan to resist racking of the wall... for lateral loads? If it's the WHOLE wall full of windows you are gonna need some solid shear wall.. I think. Maybe something like this  

You might be able to get an LVL 6x6 (think of a post type member) and use that instead of building up the 2x4 + the plate on the bottom. 

You can't buy 22' long 2x4's.
 

Plan your joints to land on studs, and stagger them from each other (to resist wind load, so you don't make a hinge on the middle of the wall)

You aren't doing anything weird. Your spans are only 24".  
 

But racking could potentially be an issue. Will the roof have sheathing?  You may need it as a diaphragm, or build a shear wall (basically hold the windows back from the corners to have plywood at each end)

I would build that with 2x6's and no bottom plate. 
 

There's nothing wrong with building 2x4 headers for that small a span, but I don't like doing it (and I'm pretty sure it's not in the code book). It's just a personal thing for me- I don't like 2x4 headers. 

There's another problem with 2x4's...

They are almost universally graded as "SPF".  That means "Spruce, Pine, or Fir". Basically, it's not graded at all. It looked like a Christmas tree before they cut it. 
 

SPF isn't suitable for headers (it's not usually in the span tables at all). It's usually pretty straight, but it flexes too much (modulus of elasticity). You want SYP (or Douglas Fir in the North). It's stiffer, but it also twists a lot when it's cut down to 2x4s. 
 

It's easier to just use 2x6s.

Good points about shear. The windows will have about a foot of wall between them, and a foot at the ends. And about 2' below the windows to the cinder block foundation. So there will be area covered with OSB for shear. 

My local lumber supplier recommended an LVL.  It's more expensive, but less labor screwing the whole thing together. I am not sure if LVLs have an orientation they're supposed to be used in, I needs to ask their engineer. 

2x4 header is fine for spans under 4' from what codes I have seen. I thought about using a 2x6 instead, not sure how that plays with the window installation. I guess it would be fine?

This whole wall is actually replacing an existing wall that was rotted out. And that wall was constructed...uh....not well. And it still stood since 1982. And was still standing. Roofing is going to be metal on purlins, with insulation. 

In reply to volvoclearinghouse :

2x4 is definitely not suitable in a load bearing wall for 4'. Something is not translating correctly. 

In reply to SV reX :

Good point about 2x4's. Code around here does not allow 2x4 load bearing walls, they must be 2x6. So that's what this is. Curious they do allow 2x4 for short headers, I guess they figure they'd be tripled up and reinforced with osb?  

LVL seems like massive overkill for 24" spans. 
 

With no sheathing on the roof, I'd definitely give some thought to shear. If you reduce the space between the windows to 8", you'll increase the corners to 3'. Put plywood on both sides with glue and twice the nails and you'll be good to go. 

In reply to volvoclearinghouse :

I've never seen a code that disallowed 2x4s for load bearing. 
 

How about an interior load bearing wall?  Does it require 2x6?

Something isn't right. 

You mentioned screwing the beam together...

Most screws are not structural screws. They don't handle shear. Nails, spikes, TimberLoks, or bolts. 
 

...or structural screws. 🤪

volvoclearinghouse said:

Good points about shear. The windows will have about a foot of wall between them, and a foot at the ends. And about 2' below the windows to the cinder block foundation. So there will be area covered with OSB for shear. 

My local lumber supplier recommended an LVL.  It's more expensive, but less labor screwing the whole thing together. I am not sure if LVLs have an orientation they're supposed to be used in, I needs to ask their engineer. 

I've seen a LOT of LVL beams so I'm 99.9% sure a nominal 6x6 will work horizontal just fine. 
 

Edit: the 2' below ain't helping much if you have only a foot between the windows. Still, you might be able to make enough racking resistance with several short shear walls if you nail correctly and use plywood (maybe even inside and out). Was the old wall just as full of windows??

In reply to SV reX :

I talkwd with a couple of local construction guys, and they both told me that exterior walls must be 2x6. 2x4 is only allowable for interior, non-load bearing walls. 

I'm aware of the structuralness (or lack thereof) for screws. Which is why I suggested Timberlocks, above. 

Agree that LVL would be overkill, but I also wouldn't have to buy Timberlocks, or spend time building the whole header thing. I really like LVLs, they're pricey but they are dead perfect and strong. 

In reply to OHSCrifle :

The old wall was literally just windows with 4x4's between them. 

volvoclearinghouse said:

In reply to OHSCrifle :

The old wall was literally just windows with 4x4's between them. 

LOL that's what I suspected. All our hand wringing about shear.. and you have a shell that already stood for (how long)?

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. 

Studs can be installed 24" o.c.  That means that technically you almost don't need a header at all (but you'd have to stack your rafters carefully on top of the studs).

There's nothing wrong with building it bigger and better, but you aren't dealing with any significant load. 

volvoclearinghouse said:

In reply to OHSCrifle :

The old wall was literally just windows with 4x4's between them. 

I don't see anything wrong with that.