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Attic load limit

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Forum topic by slick3 posted 484 days ago 931 views 0 times favorited 12 replies Add to Favorites Watch
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slick3

2 posts in 484 days


484 days ago

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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grfrazee

319 posts in 638 days


#1 posted 484 days ago

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.

-- -=Pride is not a sin=-

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Tennessee

1447 posts in 1013 days


#2 posted 484 days ago

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.

-- Paul, Tennessee, http://www.tsunamiguitars.com

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a1Jim

109187 posts in 2075 days


#3 posted 484 days ago

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Sarit

453 posts in 1638 days


#4 posted 484 days ago

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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a1Jim

109187 posts in 2075 days


#5 posted 484 days ago

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

-- http://artisticwoodstudio.com Custom furniture

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Grumpymike

956 posts in 814 days


#6 posted 483 days ago

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.

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teejk

1185 posts in 1183 days


#7 posted 483 days ago

using engineered trusses? then probably no weight at all.

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Sarit

453 posts in 1638 days


#8 posted 483 days ago

Grumpymike,
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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Grandpa

2976 posts in 1174 days


#9 posted 483 days ago

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

Granddaddy1

181 posts in 700 days


#10 posted 483 days ago

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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joein10asee

2756 posts in 505 days


#11 posted 483 days ago

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

hhhopks

550 posts in 876 days


#12 posted 483 days ago

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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