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Power poles for shed roof  RSS feed

 
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I'm building a 30x20 pole building and I have 6x6 posts every 6ft I'm thinking of using power poles for the roof. Every power pole would be 24ft long and sitting on top of my 6x6 posts. Spanning 20 ft with a 2 ft over hang. I live near the Canadian border so I will see some snow. Do you think this will work? Or is is to heavy for a roof? There will be 6 power poles for the roof? Thanks
 
gardener
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Welcome to Permies, Chris!

On reading your post I started to think I was taking a math quiz.  Um, 2 o'clock?  No?  Jokes aside, I have no idea how you'd calculate your span with round wood, but I did notice that there is a separate thread on a very similar question here:

Is a roundwood structure strong enough for a living roof?

Hope that has some answers for you!

Kim
 
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dog homestead
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In Australia I have done exactly what you speak of, but we don't have snow.
There are some factors,
- pitch of roof
- static load from snow and ice
- wind loads
- timber type

In Australia there are span tables available for use in timber framing construction, and no doubt the same
may be available where you live.
From these there will be options for wind loads, snow loads, spans and spacing and from the charts its possible to determine joist sizes.
Length of span and joist spacing is critical
 
John C Daley
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Understanding loads and span tables

This will help you understand what is involved
Good luck
 
steward
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Hi Chris, welcome to Permies!  Sorry for the upcoming list of questions but it could help others come up with the answers...

How large a diameter are these poles?  I've seen power poles with a fair range of sizes.  

Would there be a pitch to the roof or is it going to be flat?  

How much snow do you get in a heavy wet storm?  

What snow load do the building codes require for design work in your area?  

I'm pretty sure they wouldn't be too heavy for your structure.  I'm also guessing the span is too long and they'll sag, especially under snow load.  Can you put a support beam down the middle?  I know that's probably defeating the purpose of a nice pole building...
 
pollinator
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Just FYI, be careful, I almost took a delivery of old utility poles (generally they will deliver them free) and found out they are generally creosote treated. I'm not too into that, and they may have leached most of the creosote, but buyer beware.

Also, many times they are removing poles that are past their service life, and have been in ground contact. This means you are likely to need to trim the bottoms, and the upper portion has been weathered and does not have the structural strength of a new timber. The tables may overestimate your span capabilties.

 
Chris Weiner
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Thanks for all your input, I'm not totally committed to using the poles. I'm limited on funds trusses will cost $1200.00 if you have any other ideas I'm open to ideas. Thanks
 
John C Daley
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What are you trying to create, a room with wide clear spans, or will poles at say 10ft spacing work for you.
Perhaps some design parameters will help us.
As a pole home builder I can say anything will span 10ft safely, if your 6 x 6 poles are in abundance I would use more of them and think about closer spacing, but the load and span tables will help a lot.
 
Mike Jay
steward
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Chris Weiner wrote:I'm limited on funds trusses will cost $1200.00 if you have any other ideas I'm open to ideas. Thanks


I just saw post frame trusses for sale in the Menards sale flier.  24' 4/12 pitch for $117 each.  They're for 9' spacing.  Are you sure buying 20' trusses would be that expensive?
 
Chris Weiner
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My vertical 6x6 posts are spaced at 6ft apart.  I figured telephone poles would set on top of my 6x6 posts every 6ft I just though telephone posts would be stout enough to span that.  I called menards and for 20ft trusses they quoted me $1200.00. Here is a pic of my posts I have not cut them yet. I'm gonna have the front wall cut at 10ft and the back at 9ft for a 1 ft drop in 20 ft.
20180812_170149.jpg
[Thumbnail for 20180812_170149.jpg]
 
master pollinator
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I think you are looking at only one aspect of your problem when in fact there is many ways to look at it.

In this case you want to protect the items within from the elements on a budget. To do that you have several options:

1) You can add posts in the center so that you reduce your rafter span.

2) You can beef up your existing rafters (telephone poles, big beams, laminated beams, etc)

3) Using the geometry of trussing to get the strength you need.

4) Go with a steeper pitched roof with slippery building material (steel roofing) to get your snow off your roof quicker.


None of the 4 are wrong or right, but it depends on what you can get cheaply. If it was me, and I could get poles for nothing, I would put up with a pole barn with a row of poles down the center. It limits the open space inside, but you are buidling on a budget too...which is 100% commendable I might add. I would do this because putting big massive poles into place is problematic and dangerous to boot.

At my farm, I tend to go with option #3 because I have sawmills and lots of logs to make lumber. Therefore I can saw framing lumber and form trusses. But again, that is my situation.

For many people, it may be just going with option four because just getting the snowload off their roof quickly, makes the most sense.



 
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