"Wall of Windows"

[cdottrot]

Hey guys,

I'm picking up some used windows for the garage, very large (one is 70x90, others are 50x60). The west wall is 21' minus about 4' for the door at one end. Since there will be long spans, I know I need some beefy (12") cross-pieces (two sandwiched). This wall is also a supporting wall (i.e. the roof is a standard 'A' shape, and this wall is under one end of the 'A'), so I think I need to ensure there is adequate studs supporting the cross-pieces.

Will two 2x4 as jack stud work? Or should I look at something like those columns used in basements?

To clarify, let's assume that 80% of the supporting wall is windows...what kind of support will work?


(garage dimensions are 21x17, with the main door - 9x7 - on the south 17' span)

Further, I think 8' is the longest span you can support by 2x12"...this window would be 7.5' wide, so just under 8' with jack studs. Is that span length correct?

 

[cdottrot]

Found this in an older thread: http://www.garagejournal.com/forum/showthread.php?t=23949&highlight=window+jack+stud

I feel using a single jack stud on each side is OK around a normal man door or window. For larger spans I figure out how many studs would be there in a normal wall, then divide by 3 and round up if a fraction and use that on both sides. Nothing special about the formula, it just works for the stuff I do. I tend to build a little more conservatively tho since I have seen heavy loads crush a sill plate etc before and cause a sag, cracking, etc.

Say your opening would normally have 10 studs.
Divide by 3 = 3.333
Round up =4
Therefore use 4 jack studs on each side.

Or your opening has 12 studs.
Divide by 3 = 4
Therefore use 4 jack studs on each side.

Or your opening has 6 studs.
Divide by 3 = 2
Therefore use 2 jack studs on each side.

You get the picture...

BTW- I often add a second king stud on the latch side of a door for extra slam vibration resistance.

I think that kinda answers my question. Any other thoughts?

As if to say, 2 jack studs plus a king stud on either side of a 90" wide window is plenty.

I guess jury is still out on whether or not a sandwiched 8' 2x12 is ok for that span. I can always glue/nail it to further reinforce.

 

[ibedayank]

studs are 16 inches on center so how ever many you remove you need to make up that strength
to complicate this even more is the fact you want to add even more than one so you have to make up the loss of the posts with some rather large posts
then you need to make it so that wall wont come out of square by leaning front to back or side to side
for that you would need to see an engineer to draw you up some plans to make sure what you plan on doing meets building codes and will hold up your roof

lastly big windows make it easy for some crackhead to see and then steal every tool out of your garage

 

[cdottrot]

Yes, I've considered the theft aspect. I don't have that many expensive tools, and any thefts would be covered by insurance. Also, our area is pretty tame - worst thing would be some teenagers drunk and throwing rocks.

I have a friend who works for the city, I'll see what he thinks (he does permit application review, moonlights in architecture).

Some more research turned up that 8' shouldn't be that much of an issue - it's when you get up to the double garage doors, that sort, where serious structural problems occur. Most framing sites seem to agree that for 8' or less, two 2x8s are suitable as headers. However, I'd probably use two 2x12s sandwiched around plywood and nail/glue it all together. I'd double-up the jack studs and cripples, maybe double-up the king studs as well.

I have the option of getting other windows, but I think this one should do the trick, for now. Primary goal of all this is to allow a large amount of natural light into the garage for wood-working, and just help lighting in general. (and give me a nice clear view of the bird feeder/fountain - always a nice treat when I'm working in the garage)

 

[cdottrot]

Aha, this seems to answer my question:

http://www.mcvicker.com/resguide/page013e.htm

Two 2x12 will support up to 12' spans (assuming 250lbs/ft of load - no story above - and Douglas Fir #1). The 2x12 sandwich I read about should be overkill, but will allow me to rest easy. Now just to find some answers on jack/king/cripple studs.

 

[cdottrot]

Here we go:

Under Exterior Framing, Exterior Wall Openings
"Where the opening width exceeds 6 feet, triple studs are used with each end of the header bearing on two studs."

http://www.awc.org/pdf/wcd1-300.pdf

So I think that means I need to frame like so:

1. King stud ties to header (2x12 sandwich).
2. Two jack studs running under header to bottom plate.
3. Regular window framing of cripple/trimmer studs.

Worst case I'm taking out 5 or 6 studs, replacing with 6 (two king, four jack), so should be fine. Not to mention the 2x12 sandwich will be a bajillion times stronger than what's already there. (this garage was built by people who almost knew what they were doing...it's kind of a mess)

Well there we have it. I'll still check with my friend on this, but this looks satisfactory to me, if anything I'm improving the structure. Hope someone else finds the links helpful!

edit: One final note: For widths over 5', doubling up the sill plate (not vertical like the header, just two 2x4 stacked horizontally) is also recommended, so I'll be doing that as well.

 

[ibedayank]

cdottrot

good to see ya did ya reseach on the RIGHT way to do this
ive seen some pretty scary stuff done. BIG picture window and only a single 2x4 header and single jackstuds on each side the got pissed because their window cracked/broke...lol

 

[Nighttrain]

Just read this and I think your right. the span is no different than having a double wide garage door. I have seen some builds on here only using one jack stud on each side and just think thats not enough. Having multile large windows at the same height it would be better to just run a longer header.

 

[cdottrot]

Nighttrain, after my research, I definitely agree with you - a single span is better than multiple smaller spans (many of the sites I read mentioned this). At this point, however, I may just leave things with the one window (8.5x7' is pretty big, after all). Further, if I went with the long span I'm getting into engineered stuff, not something I can fabricate myself, thus more cost to a project on a very tight budget. One window is going to have to do!

 

[cdottrot]

Guys, here's what I kind of had in mind, a quick Sketchup whilst on lunch. This includes trimmer pieces that run all the way to the sole plate (jack studs). I've also doubled-up on the king studs next to the 2x12 sandwiches. That window will fit PERFECTLY under an 8' 2x12 sandwich if I go with this configuration (I think maybe an inch or two to spare).

edit: Yes, I know that a single span is better, but the 2x12 sandwich is not necessary for the 50x60 window - just overkill on my part. My research indicates that spans over 6' require above/beyond framing - this window is only 5' wide.

Thanks again!