inside leaking roof on my new woodshed all steel construction?

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Forum topic by SCOTSMAN posted 629 days ago 2031 views 0 times favorited 34 replies Add to Favorites Watch
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5352 posts in 2218 days

629 days ago

I have the most awful condensation dripping from the roof of my new all steel workshop storage shed.I have been told that applying a few thin rolls of polystyrene insulation material will stop it how thick does it have to be any other information wood be most helpful too? I am sure it’s not a leak as the whole roof inside is dripping.Alistair

-- excuse my typing as I have a form of parkinsons disease

34 replies so far

View chrisstef's profile


10696 posts in 1639 days

#1 posted 629 days ago

I wonder if a small dehumidifier would help out Alistair? In terms of the pS insulation i cant imagine anythign over 1” would be needed.

Were the roof seams welded? Maybe they burnt through a small portion?

Just tossing ideas around.

-- "there aren’t many hand tools as awe-inspiring as the #8 jointer. I mean, it just reeks of cast iron heft and hubris" - Smitty

View MrRon's profile


2797 posts in 1876 days

#2 posted 629 days ago

A spray-on insulation applied to the roof might work; the type used on mobile homes. Condensation is due to warm moist air striking a cold surface.

View Dick, & Barb Cain's profile

Dick, & Barb Cain

8693 posts in 2932 days

#3 posted 629 days ago

I had a friend who built a ice fishing dark house for spearing fish out of aluminum sheets.

When he lit his small heater, condensation would build up, & freeze it would melt, & drip off of the sheeting.

-- -** You are never to old to set another goal or to dream a new dream ****************** Dick, & Barb Cain, Hibbing, MN.

View Built2Last's profile


224 posts in 2110 days

#4 posted 629 days ago

This is the reason they build most storage building out of aluminum, it doesn’t do that. With steel, you would have to keep it bone dry, so I don’t think a dehumidifier would help. If it got the humidity low eoungh to stop the condensation, you lumber may get to dry. You best soulution, is to put fiberglass insulation on the top, preferebly the kind with a plastic backing like they use on Butler type buildings. I built an 80 by 88 shop with steel roofing and had the same problem, ” like a rain forest up in there”. You can also spray the foam type but here its hard to find someone to spray a small building. Good luck!!

View Don W's profile

Don W

14880 posts in 1200 days

#5 posted 629 days ago

It needs to be thick enough to keep the warmer moist air from making contact with the metal. I would suggest talking to someone who knows your climate conditions for what you need.

I think mrron is on the money but don’t know how thick it should be.

-- Master hand plane hoarder. -

View teejk's profile


1208 posts in 1317 days

#6 posted 629 days ago

condensation issue. I was told NOT to spray foam since the steel and material expand/contract at different rates leading to pockets of moisture that will cause a premature failure of the steel. cut in gable end vents to start (warm air seeks cold air). an industrial ceiling fan (pretty cheap) would help also I think.

View patron's profile


13018 posts in 1974 days

#7 posted 629 days ago

most old tin roofs just laid the tin on cross stringers

would rot the top of the wall plates and stringers
from the condensation thru the metal

the way to stop it
is why they put tar paper
under the metal
so the water goes out
without catching on the stringers or wall plates

like a sub-roof for the water

many old barns were so open
that it wasn’t a problem

-- david - only thru kindness can this world be whole . If we don't succeed we run the risk of failure. Dan Quayle

View Don W's profile

Don W

14880 posts in 1200 days

#8 posted 629 days ago

When I built my shop I was told to plywood the roof instead of using strapping because it would prevent condensation. Its worked so far.

-- Master hand plane hoarder. -

View HorizontalMike's profile


6925 posts in 1547 days

#9 posted 629 days ago

I’m sorry to hear that Scotsman. Is it too late to add a roof vent? On my metal shop I have an 8ft long vent along the gable. It has a chain pull to open and close the vent from the inside. Just a thought.

Similar to one of these:

-- HorizontalMike -- "Woodpeckers understand..."

View 404 - Not Found's profile

404 - Not Found

2544 posts in 1602 days

#10 posted 629 days ago

Any chance you could post a photo Alistair?

There’s a number of things you could do, but without knowing the construction it difficult to know where to start.

Also, would you be able to take the roof off in the spring or are you trying to avoid that?

View teejk's profile


1208 posts in 1317 days

#11 posted 629 days ago

was thinking the same thing Renners…without knowing the structure it’s hard to make suggestions. Cheapest solutions though would be to get the warm moist air outside (warm air moves to cold air) via gable vents or drive it back down via fan(s).

surprised he doesn’t have a ridge vent on the top (pretty much code now I think)...I have it in my steel building along with ventilated sofitts that creates an automatic air flow.

View juniorjock's profile


1930 posts in 2398 days

#12 posted 629 days ago

Lots of good stuff here. I’ve had the same problem. Cold meets heat = condensation. I installed some R13 insulation and I think that has taken care of it. I do pull it out in a couple of places to check it every now and then. Just wondering if a vapor barrier would help or would that be worse because its on the paper side of the insulation??

View HorizontalMike's profile


6925 posts in 1547 days

#13 posted 629 days ago

You may be on to something there. Insulation will sure help minimize temperature fluctuations inside, but one still needs to vent air on those days of extreme variation. I think I am using something called Solartex, or the like, on my shop. It is only 1/4in thick, has a vapor barrier, a radiant heat barrier, and 1/4in of fiberglass insulation. In south Texas this is perfect! In the middle of winter I can heat my 24×30 shop with a single 1000w baseboard heater. I get up to mid-60s within a couple of hours.

-- HorizontalMike -- "Woodpeckers understand..."

View DrDirt's profile


2409 posts in 2375 days

#14 posted 629 days ago

Good Points, I have seen best results on metal buildings (Morton is the big company here in Kansas) but there are others, is to go with the spray on foam, as there no water trapped anywhere.

Allistair didn’t mention what he was using for heating. If it is kerosene or Propane, there is a lot of water there. So an option depending on how warm you like it, and the kwHr rate for electricity is to use an electric heater.

-- "If we did all the things we are capable of doing, we would literally astonish ourselves." Edison

View SASmith               's profile


1575 posts in 1620 days

#15 posted 629 days ago

Around here most pole barns have something like this to prevent condensation. It is less than a half inch thick. Not sure of the R factor (low I’m sure) but it does prevent condensation.

It is typically installed between the purlins and the roof metal.

-- Scott Smith, Southern Illinois

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