Small Pole Building Question

[jerseydog]

Hi Everyone,
I'm preparing to build my first pole building. It's very small compared to what you all probably have. It's basically a shed - 16'x20'. I've been working out the details by reading this forum and other sites around the web. My question right now is about the number of poles that I need on the gable end. More specifically, on the gable end, do the pole(s) need to go to the top of the truss? Take a look at this drawing for a clearer explanation.

 

[LD1]

Yes the posts need to be full lenght. That is what gives the trusses lateral support to keep them from doing the domino effect.

If the posts are to be 4x4, then I would leave both. But if going to be 4x6, you mught be able to get by with just one in the middle. But whatever you do, check the local codes in your area if they apply. You dont want to build something not up to code and have to tear it down.

A couple other things worht noting...Given the shorter spans of the posts (looks like 8' at most over the door) the 2x10 + 2x8 header is probablly overkill, but I see you are in NJ and you probabally get alot of snow and the cost difference to downsize would be minimal so...its your call.

I also dont see any knee braces in that drawing. That is something I would definatally add. IT adds alot of rigidity to the structure, as well as shortening the effective span on the header boards. If you are using 4x6 posts and 6x6's in the corner (which is typical around here but I dont know on that small of a building), a 2x6 knee brace, and sandwiched at the top between the two headers is the way to go.

Also, what are you doing for siding? Metal? or sheeted and vinyl?

 

[Dr Dave]

Eight foot on center for pole spacing is common. One pole in center is fine, if properly braced,and use end trusses, pole can stop at top of wall. I would go bigger, at least 24' long,maybe 24' wide. This is a common truss size. If using pole barn trusses you cans space at 8' or 4'.

Dave

 

[heviduty]

Yes the posts need to be full lenght. That is what gives the trusses lateral support to keep them from doing the domino effect.

Doesn't the sheathing or roofing do that?

 

[jerseydog]

Thanks for the information and advice! The reason I'm showing 2 poles on the gable end is because I want to have an access door to the attic storage area. If they do in fact have to go all the way to the top of the trusses, then using only one would block my door. I figured that the 2x10 and 2x8 were overkill (especially with a 12/12 pitch), but I would rather overbuild than underbuild. And yes, we do get heavy snow here in NJ sometimes. The building will be sheethed and sided with vinyl. The roof will be sheethed and then asphault shingles. I will definitely add the knee bracing. Thanks for the tip! Unfortunately, 16x20 is as big as I can go in the area of my yard that I'm putting it.

 

[KennyG]

We need to back up on this one. The poles do not have to be any longer on the gable ends. Has anyone ever seen a commercial built pole barn with long poles on the gable ends?

The sketch shown is very odd framing. In the first place, the roof does not have trusses. It appears to be a stick built rafter roof, but it doesn't have a ridge pole. I've seen roofs built like this but they are very unstable. The roof should be structurally sound without the walls or poles. If using trusses, it should have proper bracing under the rafter members, run at an angle to make the the roof rigid. If you stick build with rafters, and use a proper ridge pole, the sheathing or purlins will make the roof rigid, but I still like to run a few diagonal braces under the rafters.

 

[LD1]

Doesn't the sheathing or roofing do that?

Depends. But not nearly as much as the extended post does.

If the sheeting is plywood, it would be better. But not as good as I would prefer. With no x bracing, there is little stopping the all the trusses from doing the domino effect. This can be overcome with some bracing once the trusses are up, and still is braced usually even with the longer pole, but it is just easier to start with the long pole from the get-go IMO. And less bracing is required if you so choose

 

[Carl_NH]

I built this 24x36 with 12/12 pitch and full second floor open. 2x10 rafters 16" OC and 18" floor trusses so no poles on the ground floor.

I used full 2x6 rough pine for the wall and gable framing, and 1" rough pine sheathing EXCEPT on the end walls the engineer and town made me use 5/8 plywood (they couldnt calculate shear factor of 1x pine) to eliminate the domino effect.

Also under the 2x12 ridge beam we tied each rafter together with a 4' long 1x6. One thing I learned is NOT to put a access door on the front side - put it on the gable end - the snow makes a BIG pile in the winter.

Good luck.

Carl

 

[LD1]

One thing I learned is NOT to put a access door on the front side - put it on the gable end - the snow makes a BIG pile in the winter.

Good luck.

Carl

excellent point. I made that mistake on mine. But really no other way around it

 

[dave1949]

excellent point. I made that mistake on mine. But really no other way around it

It's amazing how wide the gable ends of a building have to be for multiple doors. For example, two 12' ohd's and a 3' man-door would need 36' of width to fit nicely. And 12' ohd's are about the minimum most would want for compact tractors and attachments.