shed tin roof sweat ?

[blazer2007]

I tore down my old shed and built a new one with a tin roof but now I have condensation in the morning when the temp is just right with humidity . Just a 10x10 shed , no insulation , lots of ventilation. Any easy fix for this. I did read painting the underside helped.

[Redneck Rydes]

before I put my tin on I put house wrap on over the strapping, moisture just drips out the end

[72c20customcamper]

Most likely humidity coming up from the ground. Did you use wet or pressure treated wood ? Pressure treated gives off a lot of moisture untill it dries. I always put a vapor barrier under the floor nothing special just some 3 or 4 mill plastic .

[blazer2007]

no treated wood and shed is above ground on those 4 way cement blocks

[GOPAPA]

The best way to fix that is take the metal off and put 1/2 inch OSB on and then 15lb felt paper ,,,,,,,,,then the metal roof , ,I have built barns and sheds in the northwest and any frosty morning soon as the sun hit the roof this will happen to sheds with no insulation under the metal ,, you can use plastic but ,, if the shed is open where birds can get in ,,they like living in the plastic close to corners..

[mongocanfly]

Humidity and Condensation is a huge issue here..if we dont use the underlayment insulation barrier under our metal roofing itll sweat like crazy..even out in the open..
What we use here is a foil backed,1/4" thick ,white on the other side barrier...being 10x10 it wouldnt be a big deal to pull the tin back off...you can get that stuff here at all the building supply places
Heres what we use

[72c20customcamper]

Originally Posted by blazer2007

no treated wood and shed is above ground on those 4 way cement blocks

Humidity from the ground will go right threw wood flooring e en off the ground. Once it hits the tin it condenses. Even cars parked over dirt or grass tend to rust faster because of this

[Dead Parrot]

I have a metal awning the PO installed over the cement porch. It will do the same thing some mornings.

If you don't want to take the metal off, there are varieties of spray on insulation.

[GOPAPA]

Originally Posted by mongocanfly

Humidity and Condensation is a huge issue here..if we dont use the underlayment insulation barrier under our metal roofing itll sweat like crazy..even out in the open..
What we use here is a foil backed,1/4" thick ,white on the other side barrier...being 10x10 it wouldnt be a big deal to pull the tin back off...you can get that stuff here at all the building supply places
Heres what we use

That looks like some nice insulation Mongo ,,I believe you are on to something and with OSB so expensive now ,,this insulation you have shown is lot better than that big roll of the plastic quilted insulation that was used in the 70ie,,80ies and 90ies out in the north west.. After my first 2 barns 24 x 60 I used OSB or plywood from then on I only built buildings with plywood or OSB /felt paper under the metal and guarranteed no sweating and never had one to sweat. I was the go to guy for awhile because of the no sweating buildings I built,,

[special-K]

I get a lot of transition moisture (dew and morning mist) where I live. Especially this time of year. I have metal roof on several buildings and none of it sweats on the underside. I wonder where the line is drawn? All mine are over lath, no plywood, and no vapor barrier.

[blazer2007]

Originally Posted by mongocanfly

Humidity and Condensation is a huge issue here..if we dont use the underlayment insulation barrier under our metal roofing itll sweat like crazy..even out in the open..
What we use here is a foil backed,1/4" thick ,white on the other side barrier...being 10x10 it wouldnt be a big deal to pull the tin back off...you can get that stuff here at all the building supply places
Heres what we use

I read about that stuff will see if I can find some In Canada, in the mean time I tried a old pillow case and stapled it to the rafters. Should have the same effect , soak up the drips and dry out later. I will see if it works when the sun comes out

[LS short box]

I wonder if you sprayed the under side of the tin with spray bomb under coating if it would help? It's thicker than regular paint so it may absorb the heat changes?

[blazer2007]

Well the pillow case worked, soaked up the moisture and then dried out. Maybe a thicker flannel bed sheet. I,ll go to the thrift store for some used sheets and cut into strips and staple between rafters. It,s only a shed , just trying to keep nuts and bolts and spare wood from getting wet. It usually happens in the fall and spring for the moisture . Might try the under coating as mentioned as well.Hope this helps others. I do have a other small shed that has the plastic corrugated panels and it doesn,t sweat .

[dieseldawg142]

we live in BC, land of snow and rain and being in the okanagan, extra sun for you-metal condensates-period. just like your car window on a cold morn, you crank on the heater and hit the inside of the glass with heat while the outside of the glass is still cold, now you wish ya had wipers on the inside of your windshield... same principle for metal roofs (dewpoint) prob at it's worst in the morning and in the late afternoon i bet.
some good idea's here, but ultimately your roof really wants some underlay.
it's been a standard building code in bc like forever. yes, it's just a shed, but any metal roof should have underlay. water (even condensation) will over time drain your bank account if left unchecked.
my carport over my quad trailer is wide open, but it will still condensate.
i built it 26 yrs ago and used 30lb non-perf felt but i will be changing it. felt was good back in the day, but modern technology has given us better products to use.
synthetic underlay is where it's at now. won't degrade over time, is completely waterproof if your metal blew off or a tree punched a hole in it, impervious to rodents and birds, won't tear like felt, and doesn't shrink over time like felt does. Birds, decay, and shrinkage is why i'm changing mine (plus i'm going with a diff color metal)
prob not the answer you were looking for, but it is the best one. a 10x10 shed , if you used normal dura clad metal, that would only be like 6-7 sheets to pop up, if you used hidden fastner, a little more, around 18-20 pieces


any synthetic will work fine-too bad your 3-4 hrs from me, i got like 10 or 12 rolls of this stuff kicking around. as were always busy, quite often we will go slap synthetic on a roof and leave it for days or weeks till we can get back to do it, by itself it will keep you and your junk dry wit no probs. drive around to any new construction or re-roofs and you will almost always see this stuff up there, whether metal, shingles, slate, etc etc.It's like a temp. roof so work can still go on inside the building.

[blazer2007]

thanks I will look at that, roofing store is 2 blocks away but everything is 2-4 blocks away here.

[blazer2007]

Thought I would try some suggestions . Pillow case worked pretty good and I ffound some asphalt undercoating in the paint supply. It worked not bad , was moist to the touch but no drips. It was messy thou, all over my hands and glasses and every where else. That,s not a drip in the pic