Metal Shed Roof is Bad Idea

Remove the metal sheeting from the roof.

This time, lay some sheeting down first (osb), then some felt paper. Then put the metal roof back on.


You're welcome.

 

Agreed. At this point I’ll just asphalt shingle the sheathed and vapor barrier deck.

 

Not necessary to spend more $$. If you are careful, re-use the metal.

If you choose to not re-use the metal, I highly recommend using rolled asphalt roofing as opposed to shingles for the roofing material. Due to the low pitch of the shed roof, it is recommended.

 

What he said!

 

It looks to me that it is leaking. Look on the dry dirt floor and looks like drip lines directly under the center beam in the second picture. First picture has two lines on the floor. If indeed those are leak lines, that will concentrate on your wood pile and create either mold or rot or room for bugs, etc.

 

It drips where it is sitting on the purlins. The screws are not leaking. It doesn’t drip at all when it’s raining.

 

Is the condensation on the underside or on top? I am wondering if the moisture is coming up out of the ground.

 

Wow. Strange indeed.
I have a 30’x24’ outbuilding with metal roofing. Only airflow is two barge bays have no doors. Never once saw enough condensation to make one drop of water. Open ceiling built with trusses.
My guess is backwoods is correct about the stringers running sideways. That stops the natural flow of air up the slope of the roof which is almost a constant. That and maybe your particular environment.
I’ll admit I’d never thought it possible in a building as open as yours but there it is. There are metal roofs all over the country that don’t do that. Only difference is your roof joists are sideways.
Good luck with the fix.

 

A new roof will cost me about $1500, and that includes adding an additional 12’x12’ bay, and a roof that overhangs 18” all around (currently flush with 12’ OC posts.

Based on FHC members comments and ideas, I’m going to add 1” x 2” furring boards, front to back, on top of the horizontal purlins, under the metal roof sheet (between them). I will report on how that works. It will buy me some time until I can fix it up right and it won’t cost very much if it works. Thanks.

 

Is this a peaked roof or "lean to"? If it is a peaked roof, your center ridge cap is either missing its foam fillers or it needs a wider cap. It has to be running down the inside of the metal and running off of the beams, you can see the drip lines on your beams. When raining, the force/flow of the water is forcing it down the outside where it belongs, once the pressure is off, it leaks around either screw heads/nail heads which is bad washers or from the ridge cap. Thus any dew, fog, frost will end up inside due to the lack of being pushed down, it is allowed to sit and "slither" through the leaks.

 

Lean to. All the screws are tight and have been re-secured with sealant as well. All depends on weather. Cold foggy nights it rains under there. The whole metal deck will be sweating. I may just tack a vapor barrier under it and see how that works. My Wolfe Ridge splitter will be here middle of December and I will need all the dry storage I can get.

 

I did the structural calculations to rebuild it with 4x10x16’ headers on 12’ spans and 2x8x16’ rafters on 12’ span, OSB sheathed deck, whatever roofing, sitting atop of the eight 4x6 posts. I’d have three 12x12’ bays and a 2’ roof overhang. That’s about 700sf of awning which is highly coveted in the Pacific Northwest. 10lb/sf dead load and 20lb/sf live load for those wondering. $2000 I can build it. Then it’s no sweat!

 

Ondura panels.

 

Used them on my kids tree house, worked very well. Only slight issue for that particular use for us was the smell, but it's not terrible. Good product!!

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Interesting material. About $100/square. Cheap 3 tab is about $75/square as a comparison.

 

Last time I bought it, it was way cheaper than that. I did the barn roof at our old place about 20 years ago and a garage roof for my MIL. It was $13 per panel at that time. I tend to over buy cuz there was a lot of cobbling to do in the corners and I still have enough left to do another woodshed. Putting it on the barn roof by myself was a little challenging, but I figured it out using two home made ladders that hooked on at the peak of the barn. It went way faster than shingles would have cuz I didn't have an air nailer at the time.

 

Easy fix, staple plastic sheet under the joists, run strapping under the plastic 90 degrees to the joists to channel the water outside the stack

 

Your problem easily solved when I did metal roof over sawmill the roof supplier told me to use insulation under roof it is a 3/8 thick foam they called double bubble it has a white color to it and it works great my one other shed had the same problem and I pulled the roof off and installed the insulation problem solved it comes in rolls good luck JB

 

Corrugated asphalt panels. That’s what we originally installed on the outbuilding. Sun does a number on them. Replaced it with metal. Maybe they’re better nowadays.

 

I re-built my shed. This is now a 20 cord shed. It will end up with a metal roof but with a vapor barrier on a OSB deck.