Pole & Truss Problems

[GT2]

Sounds to me like you guys are not talking apples to apples here.
Mikef is talking traditional pole truss and purlin.
Sounds like you are talking about pole, beam, and " house style" trusses?

 

[/pine]

The OP stated they intend to use "asphalt shingles"...

I put down wood shingles on lattice (not solid decking) but I've never seen composite shingles put down on anything but a solid shingle base like OSB or plywood etc...

 

[mikefromnh]

not exactly if you want to build to most standard building codes...the beams that sit on the poles have to hold distribute all the weight...that weight (both live and dead loads) is what determines the size of the beam and the spacing of the poles...

...the type and size of the roof determines the the design (calculated live and dead loads) and spacing of the trusses (including the weight of of any lattice/purlins)

FWIW...almost any carpenter can cite common practices that are well within BC guidelines
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My point was that an engineer can design whatever you want to build -- the spacing will determine beam sizes etc. You could have 10' pole and truss spacing with purlins and OSB/asphalt.

Or you can build to the local prescriptive codes. Which are generally less expensive to implement.

 

[mikefromnh]

This is the method I have been trying to describe

http://www.weetwo.org/blog/img/purlin_girt.jpg

 

[Egon]

Maybe it should start with a soil analysis to determine load bearing abilities.:thumbsup:

Then we go on with that other stuff.

Then we find the design loads are too high for the soil bearing abilities.

Then we design a bigger pole or sink it deeper

Then we go thru the other stuff again.

Then the owner wants it four feet higher.:laughing:

Then its Miller time!:licking:

 

[RxRatedZ71]

Wow, lots of great feedback here. Keep it coming. I thought I had stated in my original post that I was using traditional purlins on either 16 or 24" centers, then 7/16 OSB, then roofing felt, then shingles. The local Lowe's has standard 20yr asphalt shingles for $51 a square. When I ran my original materials list and counted the boards, roofing, and siding material needed, I was able to save about $2k when compared to traditional metal "skin". Although I save money with that combination, it sounds like I may spend more in the long run either "beefing it up" to code OR rebuilding after it collapses b/c of poor planning initially. :confused3:

I think I will re-run my numbers and re-figure my cost again using traditional spacing and metal. Maybe if I spread my poles out to 10'OC I can save a bit with my lumber figures. A local ag store and lumber supplier has metal barn kits for sale for the DIYer and a 30x40 is $6200, but uses 29G metal.

Back to the drawing board!!!

 

[Pops15]

You need to get a copy of your local building code, then forward it to the engineer at the truss company and be sure to tell him you want shingles. The engineer will tell you about pole and truss spacing, purlin size and spacing, etc.
Resist the urge to take the cheap way out. You'll just be redoing it again in a few years. There's an old saying.......there's never enough money to do it right the first time but there's always enough money to do it over.

 

[firefighter9208]

29 ga. is find for the sidewalls. I like to use 26 ga. on the roof. I have built several this way. 6x6 on 12' centers with metal "chicken house" trusses and 2x6 perlins. 26 ga. metal screwed to the perlins.

Of course we have almost no snow load here in Alabama.

Chris