Built a 40x60 shop at the deer lease, 20x40 of it I have framed for a camp house. I have one bath, big kitchen/living area, and master bedroom. The issue I have is I want to put bedrooms on top (16'ceiling) I know it won't be 8' for the upstairs bedroom. I was thinking of using 20' 2x6's for the ceiling joist on 12'' centers with 3/4'' CDX on top, just wondering how much sag I'll have with 2x6's or will the 2x6's not work?

We have the 8" in our shop 24" centers tons of crap up there and no sag.

2x6 won't span 20', you will need at least 2x12 for a ceiling and second floor and then you will have trouble with the crown plus need bridging to keep them standing up straight. What Mrmo suggested is your best bet. If you decide to justgo with a ceiling no second floor either a beam in the middle so that you have two ten foot spans would work for 2x6 or no beam and 2x8 with at least one good strong back to tie them all together.

This. I'm afraid 2x6s will sag over time. Where's Hoppy when you need him? When I built our house I used pressure treated 2x6 for floor joists, 8 foot span, 12" centers. I believe 8' is the maximum you can get away with

20' span, I would use 2" X 12" on 16" centers.

Sight down them, and when one bows, make sure it bows toward the ceiling, and not the floor.

I would also buy one long enough to cut into 14 1/2" pieces to instal in the center, to keep them parallel. Pop a line down the center, on the top edge, speed square a line down the side of each 2" x 12", and alternate the spacers left right, all the way to the end. Sure makes decking easier when the warp is taken out of those long joists.

A scissor lift is a must have for this project.

all I would use is tji joists, dbl row of x bracing equally spaced. for 20' with floor, 12" min. due to dead weight (ply/joists) and live load of about `200 #sf (maybe, goin on memory).
use 3/4" t&g ply with a good construciton adhesive with screws (nails to set but screw the rest, no squeaks). if you plan on a second floor maybe look at a dbl pitched roof (barn style gable). steep sides with a 5 or 6/12 pitch ridge.

on that 20', if you don't have some support below you should really run a good lvl beam, above assumes interior walls for support. 2x6x12 pre stressed would be good.


hows dat?

P.S. if see if you can get the tji with the 1 7/8 ply instead of fir, much much stronger and usually a little cheaper.

the type in the pic work good but I have had the 2x3 edge split with screws

and another thing! when you use tji for joists or rafters be sure to have all the prepunched holes in alignment, makes it super simple to run elec/plumbing etc.

By the OP's original post it appears he has it already built. It does seem that there has to some walls on the bottom floor that could support the ceiling joist to make a shorter span. With that said Ijoist are the way to go. They are superior in every was even cost/ I went with them in my barndo build's loft area. also with Advantech 1 1/8" flooring.

hopalong. I am digging the way you think.

Everything is framed on the bottom except for joist. The bathroom is 10x16.......the bedroom is 10x10 which is wall to wall with 10' of the 16' bath wall........the living area is 20x14 to the bath and 20x20 to the bedroom. So the only 20' spans will be over the living 16' of the living area. I might have to use 2x12's and frame into the trust for head room on the top floor.

If any heating, plumbing going upstairs design floor joist to run with the items so that you don't have to cut into the joist if using solid lumber. A lot of info can be obtained by searching the net for wood spans. Home Depot, Lowes or any lumber supplier can help. Do make sure at least 3/4" t & g glued and screwed if not screws they make nails ring shanks for this. Use either bridging or blocking between solid lumber joist to keep from twisting. A lot of dyi info on u tube or buy a book.

Thanks for the heads up but, I'm aware of those things. I'm trying to salvage head room without modifying the truss. The bottom of the truss from the floor is 16', I already have an 8' wall with a top plate and if I add a 2x12+.75 plywood + 2x4 joist for the top floor that only leaves me with 6'2'' of head space on the top. It's looking like I'll have to frame into the truss and add bracing from the truss to the outer walls. That's going to suck.

use the trusses for the ceiling of the second floor, gain a little room.

Depending on your span from support walls you might be able to down size to 2 X 10 or a smaller truss. This is were a truss company or the wood span tables come into play. Wish you the best.
2 X 4 will sag with any type of load like sheet rock, 2 X 6 is the smallest I would go for ceiling.

2x4 joist will be tie into the top part of the truss, it will only have insulation on top.

picture of trusses?

I'll dig some up and post later.

We built a camp house inside a 40x60 also with a loft upstairs. We used 2x10 or 2x12, I think 2x12 to span it, but we put a beam across the middle supported by 6x6 cedar posts to cut the distance in half.

If I could get this picture to load you could!!!!!!!!

you can use 2x4 between those trusses, I would recommend a wall under the center though due to the 4' spacing. I would also run a beam in the floor under center, dbl 2x8 or match floor joists.

you can span from that front wall to the rear with 2x8 tji, 16" centers (just don't put any waterbeds on the second floor) 2x10 would be better. this should gain you about 8" over what you were going to do and at less cost I think.


run 2x4 from truss to truss on 16" centers flush to bottom of truss, rock will run same direction as trusses. just put a wall under center to help support the weight of the rock, you will be adding a lot with the wood and rock.


you can span up to 20' with a 2x8 tji, I would recommend using the 2x10 tho due to weight carrying capacity.

hope that made sense, just woke up and 0200 is not my best thinking period.

Get some sleep hopalong.

lol, old and rambling early am. your turn is coming.

I'm more than half way there