Splicing ceiling joists

[Falcon67]

When I was a kid, my dad and grandad built a 24 x 24 garage at our house. This would be early 1960s. I can probably still find construction pics if I look hard enough. I distinctly remember that the building was built with 2x10 joists spliced for the span. As faded memories recall, they where 10' with a 6' piece on either side of the joint, all bolted together with 3/8 lag bolts. I remember all this because I was a seriously interested kid and I climbed, hung, swung, hid, etc in those rafters and joists for a long time. That building is still standing 40 years later and looks as good as it did new.

My experience with modern glues leads me to believe that if the span table says 2 x 10 is good for 24' span at the selected live and dead loading, that two 2 x 10 x 12 with a 300% overlap splice is equivalent.

This is just thinking out loud because you can't get 24' around here except special order. Building a beam also saves $10 a joist.

There's lot of "No" about that with no engineering shown to back up the negative. Reference the shed saving threads - the shed I saved used 2 x 6s on a 16' span on 48" centers with 2x4 rafters - WAY, WAY under any current span table minimums. Yet the building and roof survived being twisted out of shape for probably 20 years before I came along.

I also put a pencil to it and you could build a 2 x 6 "W truss for a 24' span for about 1/2 what you can buy one and have it delivered. I assume many people don't build their own trusses because it would be a PITA. But my labor is free...

 

[scott37300]

People don't build their own trusses because they are not allowed by code. They have to be engineer approved and they use a special press to put the nail plates on that hold everything together. Not saying it can't be done but just saying that they won't pass inspection because they don't have an engineer stamp on them. Rafters are a different story because they are a simpler proven design that anyone can build with no special tools.

 

[Falcon67]

I can find a detailed design on the web from Canada that gives all dimensions and handles a 30 psf snow load and up. My loads here are 10 and 10, so I don't see a problem building trusses using a pre-approved plan where the minimum is a 30 psf live load. Nail plates not required - use 1/2 plywood at the joints. Gusset sizes are specified - no "winging" it.

http://www.nrc-cnrc.gc.ca/obj/irc/doc/pubs/hn/hn12/hn12.pdf

How about 24' truss 3/12 slope for 48" OC?
http://www.ag.ndsu.nodak.edu/abeng/plans/5922.pdf

 

[rodnok1]

There are plans available that include building your own trusses. Plywood gussets and proper gluing/nailing should be no problem. I'd consider getting #1 lumber for bottom.

 

[mtwaterguy]

I can find a detailed design on the web from Canada that gives all dimensions and handles a 30 psf snow load and up. My loads here are 10 and 10, so I don't see a problem building trusses using a pre-approved plan where the minimum is a 30 psf live load. Nail plates not required - use 1/2 plywood at the joints. Gusset sizes are specified - no "winging" it.

http://www.nrc-cnrc.gc.ca/obj/irc/doc/pubs/hn/hn12/hn12.pdf


Don't know if I'd have much faith in a 40 year old design passing any building codes now.

 

[Falcon67]

Most of the 24' spans I see use 2x4 bottom chord - I'd up that to a 2x6 for insurance. Most also use 3 each 8' 2x4 for the bottom - I'd use 2 x 6 x 12 with a single splice plus the gussets at the angles.

I'll bet if you tried to buy a 2 x 4 x 24 these days it'd look more like a corkscrew than a board.

 

[AMCguy]

I lie in bed at night tormented by this sort of thing. There is no code that I'm aware of that states you must use an engineered truss. A truss however, if used, must be engineered.

There is nothing wrong with good old fashioned hand framing a roof. Of course the code would have to be adhered to.

The building inspector likes to see a truss because it is a manufactured product that comes with a report and an engineer's stamp.

Around here the bastards get you either way. If you want to hand frame a roof structure, your plans have to be approved by an engineer. They will not look up the code.

I could have saved a lot of money and built a nicer, stronger truss if I was allowed to.

In your case I would think that your money would go further if you copied a truss design rather than laminating lumber together for strength.

 

[scottzilla]

In my town I could not even get my plans approved without a NYS engineer stamp on the truss spec page.

 

[Falcon67]

FWIW - there is no one here that has to approve anything. We did have a "code inspector" but he quit right after they fired the city manager. I doubt very seriously that the city will hire another anytime soon - maybe in a year. So right now it's a $50 permit to build, no plan submissions or anything else. Supposed to have a master sign off on an electrical but with no person/department to handle that I doubt it would be enforced. And as soon as I know what/where, I'm taking out a permit.

Don't know if I'd have much faith in a 40 year old design passing any building codes now.

Looks like the same design in my 1996 edition construction manual, and about the same as all the other 24' span truss plans I've seen. I also found some nice 24' span plans from 1981. Same general design with a center support and smaller gussets. Includes design details for spacing out to 8 feet. !!

 

[AMCguy]

FWIW - there is no one here that has to approve anything. We did have a "code inspector" but he quit right after they fired the city manager. I doubt very seriously that the city will hire another anytime soon - maybe in a year. So right now it's a $50 permit to build, no plan submissions or anything else. Supposed to have a master sign off on an electrical but with no person/department to handle that I doubt it would be enforced. And as soon as I know what/where, I'm taking out a permit.

You sir, are in a most enviable position. Good luck with your build.

 

[ishiboo]

You sir, are in a most enviable position. Good luck with your build.

Amen to that!

 

[Falcon67]

Really - don't think I don't know I'm lucky. I live 20 miles from a city that gives people similar hell to what get's discussed here. Have a friend with a business, that city just told him that his building was re-zoned and that if he were to sell his business, he would HAVE to sell it to something in the medical field. WTF is that about.

Found this - probably the easiest way to a good engineered design.
https://www.mwps.org/index.cfm?fuse...D=710&productID=6446&skunumber=MWPS-9&crow=10

 

[fergus]

That's it. I'm moving to Texas.

 

[lupinsea]

X2 on the trusses not needing to be the typical "pre-engineered" stamped trusses. You can come up with your own truss but it needs to be properly designed / engineered to take the loads. Might be worth a few hours (minimum charge) to get an engineer to safely design you a truss if you want to build it yourself.

For example: I designed these trusses for a project of ours. Then worked with an engineer to get them properly engineered (as part of the overall engineering for the house).

The top cord is a pair of 4x8's with paired 3x6 bottom cord. The pairs of cords sandwich a 1/2" steel plate that is the actual structural element taking the primary loads. The wood keeps the steel from buckling.

One of the guys in our officed developed this scheme for a different project. It uses some paired beams for the top cords but a sloped 1" steel rod for the lower cord to take up the tension (like a collar tie). The ends of the rod connect to steel plates sandwiched between the paired top cords.

 

[Falcon67]

That's some really nice looking work there.

Ya'll come. Just to clarify - could my city use some code guidelines? Sure - there's some pretty poor buildings around here. The city needs to know what issues are out there so they can make plans to correct the conditions. And of course, there are people that just don't want to go the extra steps to put up a safe building. When I talk to city officials (council primarily) about it, I make sure to note plenty of the horror stories on this board.

Do we need a demi-god in a while pickup driving around telling people their stuff is **** and gonna get shut down, red tagging anything that doesn't meet his/her personal criteria? No. (Last guy did some of that and if we had a bus service, he might have been under one.)

Somebody to diplomatically handle the permit process, check up on things, identify the conditions of city buildings and report to the council so plans can be made to fix health and safety issues, guide people toward better building construction and generally keep up with code issues - Yes

Our last city manager was very competent and believed in getting things done. But he wasn't very diplomatic. And in west Texas, it's kinda required. It requires a special tact when you have to work with someone on a code issue and you may well sit next to that same person at church on Sunday, be next in line behind them at the grocery store or sit next to them in the bleachers because your kids are on the same football team. People from big cities don't always "get" that.