I'm going to build my trusses for a 28' span. You may ask why? I can cut 1/2 the cost and I don't have to pay delivery.

I have two question for anyone with a 28' or 30' span garage with trusses 24" on center and a shingle roof
My plan is 2x4 trusses with to have two webs (one on each side) to support the roof. I see on do it yourself web sites that at 32'+ you need four webs? How do you recommend the attach the webs to the cords? I've heard that the nail plates/truss plates/metal plate you buy at lowes are no where near heavy enough for trusses. I'm thinking of scabbing over each joint with 1/2 plywood on each side? What is you opinion?

Thanks
Nate

 

i'm no engineer, but i dont see any reason why you could use nail plates. After all, steel is stong than 1/2 plywood. The gang nail type used in most trusses are different in type of material. use the plates that are about 12ga steel that accept screws. I am in no way being responsible for 24' span, but I have used them to make trusses for a 14' shed. Do some more research, maybe someone else can shed some light.

Stryder

 

I have used good grade plywood for plating trusses before but be sure to use an exterior grade plywood along with southern yellow pine studs. Glue and nails...too many though and you can actually weaken the joint. Be aware that all trusses need to be properly engineered for your local code (and load) requirements. Insurance companies may frown on you building them, should there be a failure down the road.

Most companies around Ga. use the galv. gang plates and which are installed using a press. They are small and lightweight but you will break the wood before they come apart. Unless you have a place where you can lay out the rafter, flat and mark the exact location for aligning the components, I would pay the difference and get the pre-fabs. If you choose to make them, lay one out, cut your 'pattern' pieces, make sure they fit and then cut all your parts using those patterns. If you don't own an air nailer, you will wish you had one before your done.

 

Nate, my house has 28' wide trusses, built by Woodstructures, Inc. up here in the North.

http://www.wsitruss.com/pb_trs01.asp


They have "standard" w-shaped trusses and Attic Room trusses, depending on your needs.

If you go to the above web page and select one of their models, an engineering drawing will pop up. You could use these drawings as a guide.

28 feet is a big span, and could collapse in the middle if not built just right. I agree, get an air nailer if you really decide to make your own.

I've home-made 30' wide trusses out of 2x4 that spanned 6'-18'-6' and these were nailed together with plywood gussets and glue at all joints. Of course I am an engineer and did all the load design work upfront before undertaking such a job.

BTW, the 28' house trusses were installed by a crane up on my second story house. The home-made 30' trusses required 10 guys to lift each one up and over the top plate on my one story addition. If they are not lifted vertically, they will snap in half at any joint. Luckily the first one we lifted went up against a side wall of the house and really didn't need to carry the load of a center truss.

Good luck!!,

Fran

 

Guys, to be safe you need to have your truss designed by a computer program that is available at some lumber yards or an Architect. If you are building where codes come into play you will have to have the design certified anyway.

 

Nate, I design wood trusses for a living. for a 28' span 1 web on each side (I'm assuming a V patern with a vertical in the center.) won't cut it. the cord span should be 10' max between joints, top and bottom chord. I recomend an M patern with a vertical in the center.

For trusses like this we would use 20ga nail plates (and I'm in Wisconsin, I see your from KY) The thing about the nail plate is they have to be set properly. this can be done on a flat surface with 2 steel plates (1/2" thick or so) and sledge hammer. If you do this on your new slab you see what can happen. And if the joints arn't held tight the slightest gap under the plate weakens the joint considerably. So ply wood gussets would be your best bet. Makes the truss much stiffer when your man handling them like fran said.

I would shop around alittle more and recheck your figures. you gotta be gettin a real good deal on lumber to be saving that much.

Good Luck

 

All,
Where can I get some truss design software?
I am interested in designing a 40' span attic truss with a bearing wall at its center point. Technically, this is a 20' span, kinda?
KingFisher

 

mleichtle,

I sorry, I wasn't clear. From f4fran's web site my plans are like the R285
http://www.wsitruss.com/pb_trs01.asp2x4's
Built with 2x4's

I have figured it up to be $25 in lumber for each truss this does not include my joint ties (plywood). All the truss companies around are wanting $65each + delivery so I thinks I'm going to lay out a gig and start nailing (yes I have a air nailer, thank goodness), that is when the weather breaks.

Thanks
Nate

 

Don't forget bracing, Thats the little "X" boxes on the webs. If your not drywalling the ceiling you need to brace that to. If you can download the HIB-91 It shows how.

 

If this was my house, now would be the time I would nail the trusses for hurricane brackets.

 

Nate, I happen to be a wood truss designer, I've been doing if now for about 8 years, if you want to build your own I would recomend the plywood for sure. Take it from someone who's done many field repairs... you'll kill yourself trying to hand drive those plates. If you had a friend that worked at a mfg facility you could probably borrow their portable press for a weekend... we have 2 here... but I doubt the would rent it out. Anyway if KY falls under the same snow and wind classifications that GA does you should be able to do 28 or 30 foot with the fink ("W" wev pattern) SBC requires a maximum of 8' between braces on the Top Chord and 10' on the bottom so the 30' is pushing the standard but we do them all the time... 2X4 SYP #2 or better on the top and bottom chords (rafters and ceiling joists) and 2X4 SYP #3 or better on the webs. SPF lumber is OK... but it's not nearly as strong as the pine. If you want I can run you an engineering sheet and spec out the gusset sizes. It would give you a cut list and all too, should make it easy. Just don't forget about what mleichtle said about the bracing, I would hate for you to put that much work into it and then have it come down like a bunch of dominoes. I have some copies of the HIB-91 here I could send you. I am leaving here soon to work for a steel truss company in TX but if any of you guys need any truss info in the future I have the truss design software on my home computer also.

 

To add to this a bit, I'm not sure what the pitch of the roof is, but our 4/12 trusses run $52 per truss @ 28' and $55 on the 30' ones. I don't know what your time is worth to ya but I know my guys could knock out a garage here in less than half a day... If your doing it yourself, even with a nail gun you still have to use construction adhesive (liquid nails) between the gussets and the truss members. It's a lot more work then you think. But good luck, let me know if you have any questions.

 

I built the trusses for my garage back in 1980 and figured I was saving about half the manufactured truss price.It's a lot of work for sure and I was 20 yrs old and valued the experience.I still think I'd go ahead and buy them if I were doing it again.I don't really know though,since then I've added onto the building and the trusses I built for the add on weren't that bad.I guess experience helped.

 

Johnboy,

You are the man. How can I get specs from you on four different trusses:
28' 4/12 pitch
28' 5/12 pitch
30' 4/12 pitch
30' 5/12 pitch

If I was to go with a 30' the top cord will be over 16' by my calc. Can this top cord be spiced (as long as it is near where the web meets the cord)?

I'm also going to have two 16' garage doors (on the load bearing wall). I priced LVL as a header $$$$$$$$$$$$$$$$$$$$$$$$$$. Do you have any other ideas? Of course the is the traditional 2/12 with plywood (i don't think I want to risk it at 16') I've also heard of a 3/8" or 1/2" sheet of flat steel bolted between 2x12's (this may be more expensive then LVL, haven't priced it yet)

Thanks for all the insite
Nate

 

Engineered lumber for you garage door headers is probably your best bet, if it was on an end wall where the gable was I would say that you could get away with 2X12's and 1/2" Plywood but if it's a side wall where the trusses are sitting, go with LVL or something like it. They make some Glu-Lam products that are specifically for garage door headers that may be cheaper, most building supply places should stock these. As far as the specs go, I can either fax it to you or do something like a pdf file. Your question about the Top Rafter length is correct, 16'11-1/2". If you can't find 18' lumber you can splice, and splicing it at the web joint is your best bet. Remember, a truss works by load transfer through tension and compression, picture it as if your truss was hinged at the peak, and you just had a rope tied to the ends of your rafters at the bottom. As you push down at the peak you "compress" the rafters and the rope tightens or "tensions" at the ceiling joist, so be sure that any splices you make, especially on the bottom are done well enough that the joint won't seperate.


How much overhang do you want? I'll run them up and get the specs ready, just let me know how you want me to send them to you.