Pole & Truss Problems

[RxRatedZ71]

So after many months of browsing TBN project threads and posts (I think I'm on page 76) I've decided to build my own polebarn. I've decided on a 30x40 with a 10' shed along one side. My sidewalls will be 12' high, and I'll have a single 16'x8' OHGD. My needs are basic: tractor storage, lawn mower storage, hobby/work shop space, etc. I can't afford concrete right now so gravel will work for my floor. I want to use SmartBoard panels for the siding and a 3-tab asphalt shingles for the roof. I just don't care for the steel panel look.

I've cleared my pad and had 40yds of pack-dirt brought in this week so I'm ready to roll with this project, but my problem is that all the plans out there indicate 10' spacing for the poles. With the asphalt shingles, I thought the roof would be too heavy for 5'OC truss spacing, so I've changed that to 4'OC. This causes me to change to 8' pole spacing. My local city codes dictate that I need a set of engineered plans OR comply with 2006 building codes in order to approve my permit. Now I can't find any plans out there that use this type of material with similar spacing to my project. :confused2:

Was I wrong in over-estimating the weight of the asphalt shingle roof? Would the 5'OC truss spacing actually work? I plan to use 2x4 purlins (either 16-24" on center) and then obviously 7/16 OSB underlayment.

P.S. I'll post a few pics of the barn site.

 

[BTDT2]

Go with a taller door! Read this in 2-5 years and you'll be saying, **** I should have listened.

 

[Egon]

Talk with your truss designer.

 

[EddieWalker]

Local code is what you have to follow, and what we say wont matter. Since you are new to building, I would strongly suggest that you contact your inspector and explain to him what you are going to do, then ask him for his advice on what he'd like to see. In my experience, they are usually very responsive to giving out advice when asked for it in a nice manner. I think they get allot of grief from people trying to BS them, and it's a nice change when somebody is nice to them.

Have you used SmartBoard before? It sounds like a nice product, but I question how well the seams will hold on you and how cost effective it is. I tried doing the same thing with Hardi Panels, and regeret it. I love the concrete fiber type products for exterior walls, but have come to realize that with 4x8 sheets, the seems are a big issue. If they crack at all, water gets behind them and you have to deal with where it goes when it gets to the bottom of the wall. The house wrap does a good job of keeing the water out, but if you have any areas that the house wrap doesn't lead the water away from the wall, you will have moisture issues inside your walls. With a pole barn, it might not be that big of a deal. With a house, it's a disaster.

I've also recently discovered James Hardi house wrap. From what I can tell, it's easily twice as good as Tyvek or the other brands out there. The weave it much tighter and it feels thicker to me. While I've never had a problem with Tyvek, I'm only going to use the James Hardi wrap in the future.

Good luck,
Eddie



I also agree on the taller door. My shope has 12ft walls and I went with a 10x10 roll up door. I debated on going wider, but wanted the wall space. I had another shop with a 12ft wide door and didn't think that I needed that extra width. So far, I don't miss it, and would go with the 10x10 again. I really like roll up doors, and strongly suggest you look into them. They don't take up any ceiling space, which is nice for lights and attic access. They close fairly tight, keep out the elements and wind better then most other types of doors, and they are not that expensive when compared to other types of doors that you would buy. I bought mine from Muellers, which manufactures their own doors. I really like dealing with them, and highly recomend them too.

 

[/pine]

With the asphalt shingles, I thought the roof would be too heavy for 5'OC truss spacing, so I've changed that to 4'OC.

I am curious about the type of sheathing or shingle base you intend to use with your trusses 4' OC ?

Most roofs with more than 2'OC trusses employ 1x or 2x 4 lattice and metal roofing.

 

[MarkV]

I think you will have to go with trusses on 2' centers max. I don't know of any sheathing, ply or osb, that will meet code with trusses on 4' centers. That is the disadvantage of asphalt shingles over metal roofing.

MarkV

 

[/pine]

I've built several shelters that used laminated trusses set on 5' centers and then decked with 2x8 T&G yellow pine and then shingled but it would not be cost effective for that size pole barn IMO...

 

[mikefromnh]

The pole and truss spacing can be whatever you want -- just need purlins designed to hold the weight.

You could have 4' or 12' spacing with the correct trusses and purlins. Talk to the truss companies engineer.

 

[Mousefield]

We are just looking ourselves at putting up another barn/coop. We would use fiberglass shingles not asphalt. Both are available but not that much price difference. Fiberglass should last longer and more fire resistant. Is there a particular reason you would use asphalt?

 

[/pine]

The pole and truss spacing can be whatever you want -- just need purlins designed to hold the weight.

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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Is there a particular reason you would use asphalt?

I think they may have meant it in a general sense ...in reality even "fiberglass" shingles are just "fiberglass reinforeced asphalt"...unless you are referring to a hard shell type roofing tile?