Spa cover trusses?

[handirifle]

Not a cover over the spa itself, but one over the pad the spa is on. The pad is 18' x 18'. The current plan is to build an either 4-12 or 6-12 pitch gable roof, covered with comp shingles. I have 6x6 post anchors already set in concrete, with appropriate footings. The rest of the pad is at least 4" concrete with 5/16" rebar on 16" centers.

This is going to be built as soon as I finish my current project, my workshop. It has a truss roof, but I had those made. Problem is, I am running out of funding, and am considering making my own trusses this time. My quotes are $80 each and I think I can make them for about half that. I will confirm this price before I make any final decision though.

I have the wood skills needed to do this, BUT what I am wondering is can I substitute plywood for the steel plates that hold the joints of the trusses together?

I think using 3/8" (or 1/2") ply or OSB (whichever is stronger) and nailed with pnuematic staples, 1 1/2" long (for 2x lumber), they would hold up as well as the steel plates, am I way off here?

Reading a bit on the net, I've seen some recommending using screws in the steel plates, but that seems like it would weaken the wood if you used too many screws. If you predrilled the holes it might not split, but that is tons more work than neeed be.

Hammering them on also has issues of the hammer force loosening the first side, while hammering the second side in. I do not have a press to press the steel plates on.

 

[towmotor]

Plywood instead of steel:
Why not? As long as you're not living in the structure, who's going to care? It'll probably be just as strong anyway.
As a matter of fact, I have two inch thick book about framing buildings that instructs the reader to make trusses with plywood scabs.

I imagine the steel plates became the standard when truss manufacturers began using them-but you can bet that they started using them because it's cheaper, not necessarily better.

If I were you I'd make the plywood to cover about three times the surface area that the steel plates cover, and use a strong construction adhesive between the plywood and truss chords- it's inexpensive insurance that'll help prevent the joints from loosening.

 

[EddieWalker]

I've done this and passed inspections using half inch plywood on both sides, deck screws and liquid nails.

The plates, either metal or wood, are really there to keep the 2x's in place. Those are what create the truss and give it all it's strength, and why those little metal plates work. They are not very strong other then to hold the wood in place and not allow it to slide off to the sides.

I use 12 squares and get 32 of them out of a sheet of plywood.

Good luck,
Eddie

 

[handirifle]

Plywood instead of steel:
Why not? As long as you're not living in the structure, who's going to care? It'll probably be just as strong anyway.
As a matter of fact, I have two inch thick book about framing buildings that instructs the reader to make trusses with plywood scabs.

I imagine the steel plates became the standard when truss manufacturers began using them-but you can bet that they started using them because it's cheaper, not necessarily better.

If I were you I'd make the plywood to cover about three times the surface area that the steel plates cover, and use a strong construction adhesive between the plywood and truss chords- it's inexpensive insurance that'll help prevent the joints from loosening.

towmotor
Thanks, for the input, and I must admit I hadn't thought about using glue (in addition to the staples, of course), good idea.
I have always heard that the steel braces were stronger. but I must admit I question that everytime I look at how shallow the tines on those plates penetrate the wood.

I also read of someone using 1/4 ply but I am not sure there's enough layers there to make me happy.

As for not living in it, I really don't want to build anything any of my family will be under, that's not as strong and safe, in case of an earthquake.

 

[handirifle]

I've done this and passed inspections using half inch plywood on both sides, deck screws and liquid nails.

The plates, either metal or wood, are really there to keep the 2x's in place. Those are what create the truss and give it all it's strength, and why those little metal plates work. They are not very strong other then to hold the wood in place and not allow it to slide off to the sides.

I use 12 squares and get 32 of them out of a sheet of plywood.

Good luck,
Eddie

EddieWalker
Thanks. I responded to towmotor before I saw your post as well. Always good to hear the "passed inspection" part. As frustrating as county inspections can be, I know they're doing it for the right reasons.

I think I will go ahead with my idea.

One more question. On my project, it calls for 8 trusses with one center brace and two angled support braces, and the ends with 8 evenly spaced verticle braces. (they were designed by the truss company that built my workshop trusses) How did you go about making a jig for yours, to keep them consistant? I plan on laying them out on the shop floor, once it's done. That floor is 24 x 30, and I have an 8 x 12 door to take them out through.

 

[EddieWalker]

I've never had the luxery of having the space to make a truss on the ground or have the room for a jig to mass produce them.

What I normally do is build the first one in place. It's slow and tedius, but once done, it's easy to copy the results, or mass produce each part.

I build a temporary post for the middle thatwill keep the bottom chord from sagging when in place, or if using two pieces of lumber, it's a rest for both of them in the middle. The post then has another board on the side of it that goes up past the peak of the truss so I can rest the top chords on it when putting them in place.

That might be a jig of sorts since it's used to assemble each truss in place.

Then I measure, mark and cut each piece and assemble it in place.

With good notes, it's real fast and easy to get the rest of them cut and assembled.

Hope that makes sense.

Eddie

 

[J_J]

handirifle,

This may be a bit much, but sure would look noce over that spa.

Jasmine Terrace | Timber Outdoor Structure | Custom Pergola Design

 

[handirifle]

handirifle,

This may be a bit much, but sure would look noce over that spa.

Jasmine Terrace | Timber Outdoor Structure | Custom Pergola Design

JJ
Yea that would, unfortunately just lookin at it, would probably cost too much, much less buying that lumber.

I'm hoping to keep this under $2K. The baems alone would cost me that!