Building addition question OT maybe

lenray · Apr 26, 2009

Have a 48 ft. long pole building that I woulld like to add a lean to on one side.
Want to store my 5th. wheel camper and a small tractor.
The sidewall is 12 ft. high to a one foot overhang.

The camper is 10 ft. 6 in. high--the air conditioner on top makes it the 10 ft. plus.

Probably needs to be at least 12 ft. wide 14 would be better.

I could leave the 5th. wheel in the building and store my dump truck instead--it is a foot shorter at 9 ft. 6 in.

The question is with the height of the camper or the truck will I have enough fall if I go from a 12 ft. sidewall at the building and go out 12 ft.

What size of timber would be used for the roof timbers???
Will have a steel roof in Michigan.

Kow Farmer · Apr 26, 2009

Hi lenray,
I just read your question. There are a few things that have to be considered before you build your lean to. You have a 12' sidewall, your leanto height depends what pitch your current building rafter pitch is. It could be a 3/12 or 4/12. It also depends how wide you want to build your new leanto. I wouldn't go any less than 2"x8" for rafters for snow load reasons if not 2"x10". Hope this helps somewhat.

MarkB_MI · Apr 26, 2009

I doubt that you'll be able to store your fifth wheel under the addition if you continue the slope of the roof.. Assuming it's a 4/12 roof, your 12 foot extension is going to drop 4 feet, leaving you with about 10 feet in the middle and eight on the side. And if you use 2x8 rafters, the rafters and purlins will reduce the headroom by another 8-1/4 inches.

Using a metal roof, you can can go with maybe a 2/12 slope on the extension, which might give you enough clearance.

lenray · Apr 26, 2009

I understand I can't continue the currnt roof line.
Was wondering if I could make the addition some flatter and still shed water and snow on a steel roof.
I might have to store the dump truck instead of the camper. That would give me another foot to work with.
The truck is 9 ft. 6 in. high.

Thanks for the thoughts fellas--and feel free to add additional thinking.

paul · Apr 26, 2009

It's pretty dicey to change the roof pitch _that_ shallow anytime any of us mention 'snow'.

Down south, they can get away with it.

You don't say where you are located, but you do mention snow, and that means you will have nothing but trouble by making a sloped roof feed to a basically flat roof addition.....

--->Paul

Johnski · Apr 26, 2009

What's the grade like? Is there any way you could cut the grade back to get your height while keeping your roof pitch? Iff'n you can't raise the roof, lower the floor. Just a thought. Jf

MarkB_MI · Apr 27, 2009

If you heat your pole barn, I would not change the roof pitch. If you do, you'll have ice dam problems. I think you'll be OK going from 4/12 to 2/12 with steel roofing as long as the building is unheated.

I checked some span tables, and it looks like you'll be OK with 2 x 8 rafters on a 12 foot span with the rafters on 2 foot centers. I'd use 4 x 6 posts spaced every 8 feet and a pair of 2 x 10 headers (girts) to support the rafters.

Nedd · Apr 27, 2009

You will probably be okay with the listed rafters and spans below. I would take a look at your old building sidewall. If you plan on adding hangers to your old headers, you might be undersized. We use 30 pounds per sq. ft for snow load and usually 10 psf for roof (dead) load.

If your poles are 9 feet apart, the addition could add an addtional 2000# per section, to the existing headers.

Just something to also consider.

Building addition question OT maybe

lenray

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Kow Farmer

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MarkB_MI

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lenray

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paul

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Johnski

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MarkB_MI

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Nedd

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