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Forum topic by slick3 posted 12-18-2012 07:21 PM 2698 views 0 times favorited 12 replies Add to Favorites Watch
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2 posts in 2469 days

12-18-2012 07:21 PM

I have a garage 24×24 in size. Running through the center, I have three 2×12 x 24 for my support beam. My question is, does anyone know how much weight I can store in my attic? The attic floor is 1/2” plywood resting on 2×8 ceiling joit on 16” centers.

12 replies so far

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388 posts in 2623 days

#1 posted 12-18-2012 07:38 PM

I believe the IBC specifies a live load limit of 30 psf for occupied attics. If yours was designed to be unoccupied, that won’t be the case.

While I am a structural engineer, I am unlicensed, and cannot give any guarantee of accuracy without seeing your garage, the plans, and a capacity calculation for the space. Don’t take anything I say as advice in the matter, since I have no legal backing whatsoever.

Anecdotally, when I was growing up, we had a one-car garage. My dad would stack stored lumber in the rafters, though he would probably keep it below 4” thick of wood stacked in one area. This is in southeast Wisconsin, with a 12/12 pitched roof, and plenty of snow. As far as I know the old garage still stands.

Play it safe. You will probably be fine putting a few boards up there, but don’t expect to use it as a hoist point to get the engine out of your car.


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2901 posts in 2998 days

#2 posted 12-18-2012 07:39 PM

I don’t know, but I bet it is a lot lower than you think. 24’ is a heck of a span. Any chance of adding two 4X4 support beams at the 8 and 16 foot marks of the 24’ triple beams? That would make a huge difference in my mind.

-- Tsunami Guitars and Custom Woodworking, Cleveland, TN

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117713 posts in 4061 days

#3 posted 12-18-2012 07:44 PM

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551 posts in 3623 days

#4 posted 12-18-2012 10:12 PM

For my garage remodel, I’m replacing a 14”x4”x24’ doug fir beam w/ 2 16”x5.5”x19’ GluLam beams running perpendicular. I spec’d 40psf live load to my engineer.

Comparatively, I don’t think triple 2×12’s are gonna be able to take that much weight with a 24’ span in both directions. You also don’t want the beam bearing over your garage door header, which was the case in my garage.

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117713 posts in 4061 days

#5 posted 12-18-2012 10:18 PM

Some else can help with load calculations is your local truss company.

View Grumpymike's profile


2418 posts in 2799 days

#6 posted 12-18-2012 10:46 PM

Using 2X8 joist at 24’ in an unsuported span exceeds maximum horiz. span limits.
I don’t think that we are given all the facts here. Do you have a center post or two in that 3- 2×12×24 beam?
If so you now have 12’ spans; and with a fink truss your vertical load limits go way up.

-- Grumpy old guy, and lookin' good Doin' it. ... Surprise Az.

View teejk's profile


1215 posts in 3168 days

#7 posted 12-19-2012 12:07 AM

using engineered trusses? then probably no weight at all.

View Sarit's profile


551 posts in 3623 days

#8 posted 12-19-2012 12:20 AM

I think the 2×8’s will run perpendicularly across the centrally located triple 2×12 beam. Essentially splitting the 24’ span in half.

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3263 posts in 3159 days

#9 posted 12-19-2012 02:07 AM

2×8’s used as floor joist will span about 14 feet. I usually recommend attics not be used for storage. We all know how well this works but you have to try.

View Granddaddy1's profile


182 posts in 2685 days

#10 posted 12-19-2012 02:24 AM

Way too much missing information to give sound advice. A tripple 2×12 beam spanning 24’ is probably maxed out carrying your 2×8 joists. Not to mention the 3 ply beam is probably bearing on a garage door header that will receive the translated load. We’ve learnedly a lot in the post Hugo/Andrew/Katrina era that was never thought about before regarding residential structures, so unless your home is newer I’d strongly suggest consulting a professional engineer in your area. The money you spend will be cheap compared to the potential consequences.

-- Ron Wilson - maker of fine firewood!

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7741 posts in 2490 days

#11 posted 12-19-2012 02:39 AM

Note to self ... Remind me to never let you guys see what I have stacked in the rafters of my workshop :-) :-)

-- Perform A Random Act Of Kindness Today ... Pay It Forward

View hhhopks's profile


659 posts in 2861 days

#12 posted 12-19-2012 02:40 AM

A structural engineer should able to answer your question but you need to provide the proper information.
Can you provide some photos and supplement it witch sketches and data?

I am not a SE myself but having good information will make it a lot easier for someone to help you.

-- I'll be a woodworker when I grow up. HHHOPKS

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