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Old 12-31-2013, 07:22 PM   #1
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Garage attic question


I have a two car 22'x22' detached garage with a diving wall in between. I'm looking at removing the wall to create one large open room. The garage has an attic with 2x8 joists spanning the full 22' width and 7/16" plywood covering the center of the attic floor. The garage walls are concrete, and the roof is a low pitch hip roof, with all the rafters meeting at the center like a pyramid. I tore away the sheet rock on the dividing wall and noticed that the wall was constructed after the ceiling sheet rock was screwed in place, in addition a few studs were actually missing. This now has me wondering if this wall is actually structural or not? Can I simply remove the wall and maybe add some lumber to tie the ceiling joists to the roof rafters for additional support? Thanks.

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Old 12-31-2013, 07:27 PM   #2
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The wall could be load supporting. A 2x8 does not seem large enough to span 22 feet. However 11 feet seems reasonable. You need to confirm before removing.

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Old 12-31-2013, 07:51 PM   #3
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Take the sheathing off of both sides, that way you can see how the wall was built. As for from the attic space, you should post pictures of how the construction of the roofing make-up is, whether it is manufactured trusses, or built on site Trusses & Joists.
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Old 12-31-2013, 10:39 PM   #4
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I removed the sheet rock from both sides of the wall, and you can clearly see that the ceiling sheet rock went on before that wall was put up. From what I was told by an old carpenter friend, these ceiling joists are acting more as long collar ties than typical floor joists, and he assumed that these joists overlapped on top of that wall, but after removing some sheet rock from the ceiling I saw that wasn't true, and these are actually 22' 2x8s. I don't plan on using the attic for storage, so I won't be loading it down...
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Old 12-31-2013, 11:21 PM   #5
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From your description of the construction, it would seem likely to me that the center wall could indeed be taken out without adverse consequences.
The span is not too long if the original plans had called out 5 lbs. of dead load, no storage for the space above the garage at 16" oc spacing for a species equal to Doug Fir #2.

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Old 01-01-2014, 12:15 AM   #6
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If the wall is what we calla false wall, then take it down. By false wall,it is as you stated, was put in place after the construction of the building, sometime later.
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Old 01-01-2014, 05:56 AM   #7
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unsupported 22' 2x8s ? ? ? not in my garage understand your wish for clear open space BUT attics have a way of collecting weight - even the weight of people up there repairing ' stuff ',,, I'd ( AT LEAST ) have 2 columns & supporting beam installed or someday your garage floor MAY be wearing a garage roof of a MUCH lower height
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Old 01-01-2014, 09:03 AM   #8
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Don't forget that I do plan on adding braces from the floor joists to the roof rafters. Wouldn't that alone be enough to help suspend the attic floor?
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Old 01-01-2014, 09:50 AM   #9
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Mr Gump has correctly pointed out that a conventional 2x8 floor joist spanning 22 feet is capable of supporting 5 pounds per square foot, which is sufficient for dead load only (weight of the joists and perhaps some sheet rock).

The point load question is more interesting. Should a 200 lb individual stand on one of the joists at the middle, by computation you would deflect the joist downward about 1 inch, and would be close to breaking the joist (factor of safety about 1.3). If you picked a joist that had a weakness like a knot near the center, you could easily break the joist. This also assumes no dead load on the joist such as storage or a layer of sheetrock.

As to supporting the joists using braces, that is a good idea, assuming you properly attach the braces to the joist you would strengthen them.

The joists are primarily acting as rafter ties, NOT collar ties, which serve a completely different purpose. You may have collar ties, if so they would be about one third of the way down from the peak of the roof to the level of the floor joists, and would typically be relatively small stock like perhaps a 1x6 spanning from one rafter to the opposite rafter. The purpose of collar ties is to equalize uplift pressure on the roof in a wind storm, they are not there to prevent spreading of the walls, which is the function of the floor joists.
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Old 01-01-2014, 12:27 PM   #10
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2X8s on a 22 foot span, not in a house I built. If you do tie them to the rafters be sure to make sure the hip jacks are nailed really good because the nails are all that will be holding the pressure, unlike regular rafters.
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Old 01-01-2014, 04:52 PM   #11
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Originally Posted by sm424 View Post
Don't forget that I do plan on adding braces from the floor joists to the roof rafters. Wouldn't that alone be enough to help suspend the attic floor?
maybe, it depends on the loads, the location of the braces and the existing size/species of the rafters, as well as the connection method.

I totally agree with the others in regards to the span of the 2x8 joists. They may span 22' but I have a feeling the wall was installed due to issues with sagging, especially if items were stored in the attic space. This would have been a simple DIY fix.

you could always install a beam to support the attic joists. the beam could be installed either under the joists or the bottom edge of the beam flush with the bottom of the joists and connected with hangers.

I would expect for a beam to span 22' with an 11' tributary load it would require an engineered beam such as a laminated veneer lumber (LVL) beam. Each end of the LVL beam would require a properly sized column to support the load down to the foundation.

A local lumber yard (not big box store) may be able to size one for your needs, either that or a professional engineer would be able to.

I think this may be the quickest and least costly way of removing the wall supporting the joists. Just my humble opinion.

Good luck!
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Old 01-01-2014, 06:25 PM   #12
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Garage attic question


As I understand it, the OP has stated that he merely wants to get rid if the center wall that is in his garage.
From his description of the framing of the wall and the framing of the garage, I think it reasonable to surmise that the center wall was put in some time after the creation of the garage as a convenience of some kind to the original home owner.
It sounds like just a non-bearing partition wall in other words.
Of course this is all dependent upon the OP's accuracy in his description of the present situation.

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Old 01-01-2014, 09:02 PM   #13
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Alright, so a little more info on this roof. The building itself is around 50-60 years old. The rafters are 2x6s. I screwed those ties in today, but left the wall for now. The ties are about 5' in from the ends of the rafters, leaving around a 11-12' span between the two sets of ties. In addition, the diving wall has a single top plate. I don't know if that is more proof to this not being a supporting wall...?
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Old 01-01-2014, 10:42 PM   #14
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Roof sounds under built to me. I would leave the wall or at lest not plan on storing anything in the attic.
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Old 01-02-2014, 11:12 AM   #15
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The point load question is more interesting. Should a 200 lb individual stand on one of the joists at the middle, by computation you would deflect the joist downward about 1 inch, and would be close to breaking the joist (factor of safety about 1.3). If you picked a joist that had a weakness like a knot near the center, you could easily break the joist. This also assumes no dead load on the joist such as storage or a layer of sheetrock.
Yay math. Listen to Daniel - whether or not this wall existed in the first place, the math shows that it is a good idea for the wall to be there.

Personally I would never want an attic in my home where I could not walk around up there to take a look, run a cable, etc. Daniel's numbers show that moving around in this attic would be an iffy proposition if you weigh 200 pounds. I happen to be a bit under that. Certainly there are people over that.

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