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Pole Barn Shed Roof Addition. How?

andyb's picture

Got an existing 30x45 pole barn.  Upstate NY location. 

14' sidewall height. 

Posts are laminated 2x6, approx 6' on center. 

2x4 horizontal nailers 2' on center. 

Steel siding attached directly to nailers.

I need to add a shed roof on one side and am having a hard time figuring out the best way to attach to the existing barn.  First thought was to cut slots in the metal siding and bolt shed rafters directly to posts.  Concerned with the 6' spacing;  maybe not an issue with proper sizing.

Also I have to flash the shed roof/barn wall intersection point.  Any thoughts there?

Thanks for any help.



(post #106054, reply #1 of 7)

My first thought was to take the metal off the side of the shed, then extend the existing roof line down over the addition. That way you don't have any flashing issues.

How wide is the addition?

Logic is the art of going wrong with confidence. [Joseph Wood Krutch]

(post #106054, reply #2 of 7)

Another option, if you want the shed roof to attach to the wall of the barn below the eaves is to cut a strip of siding out where you want the shed roof to attach, install a header and hangars and run the rafters out to your outer shed roof support structure.

You can slip and secure a flashing up behind the upper wall siding you left above the header.

When I've done this, I've removed the siding and cut it with electric shears on a set of sawhorses, then reinstalled above and below the header. (You do, of course, need to cut the upper wall siding you'll be re-installing to allow for the height/thickness of the shed roofing and the flashing).

(post #106054, reply #3 of 7)


Have you used joist hangers at the rafter/header connection?

(post #106054, reply #4 of 7)

Yes, I've used hangars, but the pitches I've done on shed additions have been in the 3/12 or 4/12 slope so the level base of the hangar, I didn't consider an issue. If the slope was much greater, I'd maybe use the adjustable roof brackets, or (more likely) cut a little birdsmouth on the bottom of the rafter where it seats on the bracket.

But the newer Simpson brackets require a larger nail (12d or 16d) attaching the bracket to the header so the birdsmouth is probably of minor importance.

Instead of brackets, you can also nail a cleat on the bottom of the ledger and nail blocking between the rafters (nail the rafters into the blocking) which also makes a strong connection, but takes more time and material.

You do, of course, want to plumb-cut your rafters so they lay tight against the header.

(post #106054, reply #5 of 7)

do you really think the hangers are necessary?

I would think that  with the rafters cut with a plumb cut, is it necessary?

(post #106054, reply #6 of 7)

I prefer the hangars, depending on how the shed roof is configured with the rest of the structure. If the building is enclosed, the hangars are probably of less importance, but if the shed roof is open to the elements beneath, just toenailing the plumb cut to the ledger isn't going to provide as much shear resistance to wind uplift as a hangar will.

But then, I live in an area where wind is an important consideration in most building construction.

I didn't catch your post 'till just now and I didn't go back and read the OP's original description so I was going on the assumption that it was just an open shed roof.....

(post #106054, reply #7 of 7)

I forgot also, lets let it die......