Okay, so I don’t know everything and I’ll be the first to admit… but tell me if you think this is right. I ‘m working for this guy and we nee a twenty four foot 2×12 for a large shed roof (4/12) but we only have twenty foot 2x12s. Oh don’t worry, he says, we’ll just nail two twenty footer’s together, with that much over lap there is no woory about sag, and I’m thinking– with this snow load I couldn’t imagine doing that on a floor joist. So am I crazy or what? Or does this work?
Bookworm
Replies
This is commonly referred to as "Redneck Engineering".
It does not work,
but,
unfortunately,
you are crazy.
Our quarrel with the world is an echo of the endless quarrel within us. - Eric Hoffer
first, dont know the pitch or snow load or anything else
lets pretend you ar erunnig at least a 4/12 in a 4o lb load and runnig no more then a 24 inch center
and I am not even sure a 2x12 can span that.........but anyway
so........ lets pretend that all things, spans etc work for a 2x12
then first thought. im in disagreement about that you cant ( in my envoronment)
if your have 2 -20 foot 2x12 and you nail them together to get a 24 foot
I think you guys are covered
that gives you a 16 foot overlap
16d sinkers 16"oc in a "w" pattern, still worried throw some bolts wiht washer and nuts, does that help ???????????????? but Ive seen it done
the biggest problem I see is lifting the darn heavy things into place
however any flatter and any heavier of a load I would maybe look for engineering, TJ-Is, LVLs or ask Boss Hog for a truss
I love tursses
however ....would I do it..........no
a whole roof system this way, no way, looks like a chump, somebody screwed up in a design or ordering material
especially not for a paying customer
would I do it on something of my own, for just me . in a shop or something , in a pinch, yes
a repair of one.............maybe.......with permission
however wher I am , I can get 2x12 that long
Edited 12/9/2004 8:43 pm ET by Isamemon
Edited 12/9/2004 8:52 pm ET by Isamemon
And what a WASTE! Two 20 footers where one 24 footer will do? How many of hem therr hack units do they need?
As for structure, Hmm? I believe on any loaded beam the compression and tension at each end is zero and at a max in the middle. With nails and bolts, probably stronger than a single 24 footer. JUST A GUESS MIND YOU!!!! Not good enough for a . . . sure . . go ahead.
Are you talking about shear and moment of inertia? If this member is pitched, it's in compression because of the resistance at the bottom to the ridge or hip forces. Dead load isn't too much but once you add a heavy snowfall, there's a bunch of downward force pressing the roof panels on both sides of the ridge together and carrying the load to the walls. There's going to be deflection, too. More, obviously, with a lower sloped roof. Unless you're talking about tension at the bottom and compression at the top of the member. Then I agree. But I thought he was asking about rafters. Since the 2x12-24' can be used without being doubled, where they attach to the ridge and top plate will handle whatever shear is there and you know that a doubled 2x12 will deflect a lot less than a single one. It will work, but as was said before, the insulation won't fit right and it can throw off the nailing pattern. Also, if one of the 20 footers decides to go into business for itself by warping (like the ceiling joists in my house), it may cause problems with the drywall or whatever is on the ceiling. Plaster in my case.
"I cut this piece four times and it's still too short."
Edited 12/10/2004 9:33 pm ET by highfigh
Bookworm, using my seat of the pants engineering training, I'd say that would work. It was quite common in the olden days to occasionally scab things together like that.
It wouldn't pass code, but it will pass redneck code as is already mentioned.
In a pinch, I'd do it for my own stuff.
blue
Warning! Be cautious when taking any framing advice from me. Although I have a lifetime of framing experience, all of it is considered bottom of the barrel by Gabe. I am not to be counted amongst the worst of the worst. If you want real framing information...don't listen to me..just ask Gabe!
that you are...
ask anybody....
Life is not a journey to the grave with the intention of arriving safely in a pretty and well preserved body, but rather to skid in broadside, thoroughly used up, totally worn out, and loudly proclaiming
WOW!!! What a Ride!
I've done this with no problems. Construction adhesive and a million nails. The worst part is the layout for plywood, and in my case it was a cathedral ceiling, which was cedar, and it throws off the nailing pattern and makes the insulation less effective and harder to install, but I got it done and it has not sagged, and has seen serious snow at times.
Redneckily,
Dog