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Forum topic by FredIV posted 07-14-2012 03:16 PM 1114 views 0 times favorited 8 replies Add to Favorites Watch
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121 posts in 2417 days

07-14-2012 03:16 PM

Good morning lumberjocks.

I am in need of some sage structural advice or insights. I’m in the process of renovating my attatched 12’w x 21’ deep garage into a workshop. My ceiling joists are constructed of 2×4 which span 12’ feet across and are appr. 16” on center. I’ve take down the old ceiling sheet rock , insulated between the joists and started adding new sheetrock. I was wondering if I could some how cut out more than half (about 8’) of one of those 2×4 joists in order to create a small opening so I can reach up into the attic for some very light storage. This new opening would be 32”deep x 48”wide. I would frame out that new opening and support that cut 2×4 with a couple of vertical supports running from the roof rafters (2×6) down to that cut 2×4. Currently, there are a couple of those vertical supports that appear to have been added when the house was built. I’m not sure if that would create too much of a stress on the current roof rafters. I hope this description makes sense. Any advice would be extremely appreciated.


8 replies so far

View Sawkerf's profile


1730 posts in 3096 days

#1 posted 07-14-2012 03:20 PM

Are they joists and rafters, or trusses. Both can be modified, but trusses are more complicated.

-- Adversity doesn't build reveals it.

View HerbC's profile


1764 posts in 2887 days

#2 posted 07-14-2012 07:00 PM

Even if their joists/rafters I’d hesitate to modify them. Twelve foot is quite a distance for 2×4 to span. Additional weight will case them to sag…

Good Luck!

Be Careful!


-- Herb, Florida - Here's why I close most messages with "Be Careful!"

View nailbanger2's profile


1041 posts in 3171 days

#3 posted 07-14-2012 07:34 PM

What is your definition of “light storage”? If you do this (and why do I think you will), you should double up the joists adjacent to the opening. A 2×6 sistered to the 2×4 would be better. Then use a 2×6 to frame the opening and hang the cut 2×4 from that. HerbC is right, though, 12’ is a long distance for 2×4 white wood, and bolstering them by adding support from the rafters might get you into more trouble. I don’t know what your average snow load is so I can’t comment on that.

-- Wish I were Norm's Nephew

View patron's profile


13608 posts in 3368 days

#4 posted 07-14-2012 07:44 PM

if you plan to cut one joist in half basicaly
reinforce the two side ones
by adding full length joists to them
(they too need to sit on the top plate)
and with saddle joist hangers
make headers across to both sides
and use hangers to support the shorter joists
onto the headers

-- david - only thru kindness can this world be whole . If we don't succeed we run the risk of failure. Dan Quayle

View Sawkerf's profile


1730 posts in 3096 days

#5 posted 07-14-2012 10:06 PM

I just re-read your post and suggest that you find other options for your “light” storage.

It’s fairly easy to head off a rafter (or joist) and bulild a box to carry the loads, but your joists are already pretty much at their limit of their load carrying ability.

Garages are rarely built with overhead storage in mind and the joists are usually maxed out just carrying their own weight across the span. You can reinforce them, but it takes a bit of work,

On several occasions, I’ve had to tell folks that their sagging garage joists aren’t due to faulty construction, but sagged because they were never intended to carry any loads.

When we moved here over 30 years ago, I reinforced my garage joists but told SWMBO (the pack rat) that the only stuff she could store there was stuff she could personally get up and down a ladder. It’s worked really well, so far. – lol

-- Adversity doesn't build reveals it.

View Ted's profile


2873 posts in 2238 days

#6 posted 07-14-2012 10:26 PM

I’m with HerbC on this one, 2×4s are likely to sag just from the weight of insulation and drywall, much less than anything stored up there. Add to that you would be cutting at least 2 of them to make the opening and that area above the newly insulated ceiling will be very much weakened. If you wan’t to use that space for storage, I’d suggest sistering 2×6s to the existing 2×4s, and putting plywood.

-- You can collect dust or you can make dust. I choose to make it.

View OnlyJustME's profile


1562 posts in 2404 days

#7 posted 07-14-2012 10:48 PM

It sounds to me like you have roof trusses and they should not be cut at all. They are engineered to hold together and support the loads as a system and to cut them would need new engineering to distribute the forces. What would work for traditional joists and rafters would not always work for trusses. The only thing i would store up there is the insulation.

-- In the end, when your life flashes before your eyes, will you like what you see?

View FredIV's profile


121 posts in 2417 days

#8 posted 07-16-2012 01:09 AM

Thanks all. I’ve decided to not open up a can of worms. I’ll make do with what I have. All of the other houses on my street (except for one) have 2×4 ceilings and are holding sheetrock.

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