joist size ???

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Forum topic by dustycajun posted 01-26-2016 06:41 PM 659 views 0 times favorited 7 replies Add to Favorites Watch
View dustycajun's profile


71 posts in 1483 days

01-26-2016 06:41 PM

I am building a lean to, 12 foot wide , need suggestions on joist for roof , should i use 2×6 or would 2×8 be
Better. Im using a metal roof.

-- klcrd

7 replies so far

View jusfine's profile


2422 posts in 2924 days

#1 posted 01-26-2016 07:05 PM

Is 12’ the clear span from building to your beam?

It would also depend on the slope, if it is a low slope (3 or less), I would go 2×8. If more, 2×6 should be fine.

In Canada we have to consider snow load, doesn’t look by your location like that is an issue…

-- Randy "You are judged as much by the questions you ask as the answers you give..."

View bigblockyeti's profile


5120 posts in 1719 days

#2 posted 01-26-2016 07:10 PM

Houma isn’t likely to see too much snow any time soon so 2×6 would work, the steeper the pitch the better (within reason). I would personally still prefer to use 2×8 for the joists just for greater strength.

View Smitty_Cabinetshop's profile


15353 posts in 2617 days

#3 posted 01-26-2016 07:12 PM

Rule of thumb: distance divided by two is dimension lumber need, rounding up in every case. 12’ means 2×6 is minimum. Metal roof lightweight. I’d say it’s fine. Consult building codes, etc. as necessary.

-- Don't anthropomorphize your handplanes. They hate it when you do that. -- OldTools Archive --

View MrUnix's profile


6714 posts in 2197 days

#4 posted 01-26-2016 07:14 PM

Depends on the load. I used 2×6 (actually, I just ripped a 2×12 in half) on a 14 foot span for my pole barn, but it’s a pretty light roof and we don’t need to worry too much about snow down here in Florida :)

I don’t think going bigger would hurt, but going smaller might!


-- Brad in FL - In Dog I trust... everything else is questionable

View bondogaposis's profile


4727 posts in 2350 days

#5 posted 01-26-2016 07:16 PM

What is your snow load? Here it is 34 lbs/sqft. Okay, I take that back I see you are in LA. My guess 2×6 will adequate.

-- Bondo Gaposis

View conifur's profile


955 posts in 1150 days

#6 posted 01-26-2016 07:50 PM

Also consider the distance between each one. 16 or 24 on center? That also needs to be factored in.

-- Knowledge and experience equals Wisdom, Michael Frankowski

View dhazelton's profile


2767 posts in 2295 days

#7 posted 01-26-2016 08:34 PM

12 wide but how deep? Run your joists the short way and you could get by with smaller lumber.

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