If I am joining floor joists meeting atop a 2×4 bearing wall below, can I butt them and sister a scab alongside to tie them? Each joist will have 1-3/4″ of bearing, or less if we miscut a little. Is that enough? We are using 2×8 SPF, and 10/5 is our biggest span. I want to simplify floor sheathing layout. What do the various codes say?
Discussion Forum
Discussion Forum
Up Next
Video Shorts
Featured Story
The FHB Podcast crew takes a closer look at an interesting roof.
Featured Video
Highlights
"I have learned so much thanks to the searchable articles on the FHB website. I can confidently say that I expect to be a life-long subscriber." - M.K.
Replies
Gene,
here in calif its legal to butt the floor joist as long as you maintain 1-1/2'' of bearing. i believe you need to scab them at least with a 36'' block but you might want to verify that with your inspector. i find that if your butt joint doesn't fall on a 4' layout, its just as easy to use 12' or 16' joist on the side you are going to start sheeting from and just offset the 1-1/2 when you pass the 4' layout point.
I don't personally like it. Seems to me that 1.75" isn't enough. Particularly if there's an eqrthquake or something, and stuff starts moving around.
Can't quote a code or anything - I just don't like it.
I live in a two-story house.
one story is "I have a headache" and the other story is "It's that time of the month."
What if we are stapping the ceilings that hang from the joists, and a 1x3 strap is screwed to the joists tight to each side of the top wallplate, where the joists butt? Those butts would be railroaded to the wall top. Just a question.
yes, you can butt & scab... we do it that way more than lapping..
1.75" bearing is plenty for repetitive joists... most headers only need 1.5" for code
for scabs we like 1x8 ledger board ( rough spruce ) with (5) 8D nails on each side of the joint
it is very helpful having in-line joists for more than just plywood layout.. it also helps with some utility layouts like ductwork
Mike Smith Rhode Island : Design / Build / Repair / Restore
Gene,
You can do it that way, I've never seen it done around here but running the beams along side eachother is fine and me personally I think that it is stronger because by overlapping your nailing and tying them into eachother.
As far as doing it your way it takes alot longer bacause you have to cut everyone exact. That means your handling the board once to measure and cut, then your handling it again to put it up and nail it, then your measuring and cutting pieces to splice along side of them.
If your comfortable you just put the beams up in place on a flat or nail them together and cut the extra off.
As far as making it easier for running your plywood being that their lapping it's not a problem, when you get to the spot where the beam changes all you have to do is put a 2x4 nailer in.
I't's just for one row every 8' and then the following row will follow the the other side.
Lapping the beams is not a problem for duct work unless you have one side of the beams layed out 16" o/c and the other side 12" o/c or both sides 12" o/c. The duct work around here is usually no bigger than 10" wide but you still have 13" if you overlap.
If your going to do it your way, check to make sure about 1-3/4" bearing. That's always a good topic on the jobsite."What's the required bearing"
On outside walls, say 2x4's when using 2x10's we always have 2" bearing because we run our 2x10 box on first and that leaves 2" left.
If you set your beams in a joist hanger, the seat on the joist hanger measures about 2".
Hope this helps.
Joe Carola
Instead of scabbing with wood, I seem to remember something in the Simpson catalog for this situation. I think their web site is http://www.strongtie.com. Especially in earthquake country they're a good idea. Overlapping with wild ends is a tradition that goes back to the pre-Skil saw days.
-- J.S.
Gene,
I was just thinking, you said you have 10' 5" span. What is the total span including the 10' 5"?
Let's say the other side is 10' 5".
Can you just get 22' 2x8 and put them in, in one shot?
No overlapping or butting and splicing.
That's one good advantage with I-joists, you can use nice long lengths and do things in one shot.
Joe Carola
the literature we get with tji "I" beams specifies 1 & 3/4"bearing and we butt them and block them at the seam. I've never done this with dimensional lumber and am pretty sure the local inspectors would frown on it, but you should check local codes
Gene, our local code is CABO 1&2 Family, 1995. It states "not less than 1-1/2" of bearing on wood" (502.4) is required. For end butted joists, wood or metal splices are needed but it doesn't offer the particulars. In lieu of splices, (502.4.1) lets you rely on the floor sheathing to tie the joists together, provided the ply overlaps onto the next joist by at least three inches. I think I'd be happier with a 12" overlap myself.
Al