condensation in my new storage steel shed/garage sized

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Forum topic by SCOTSMAN posted 02-25-2013 03:59 PM 10661 views 0 times favorited 20 replies Add to Favorites Watch
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5849 posts in 3638 days

02-25-2013 03:59 PM

I posted already about my new steel garage which I bought this year.I am using it’s 20 foot by 10 foot space to hold wood etc as a storage facility only nothing else,so am not worried about electricity lights though they will be added later,the main problem is severe condenstaion which is very bad—severe.I have asked my local builders yard for information re polystyrene sheets one inch thick.I hope either to glue these to the roof and see if it helps.I have also been told of a paint on product which is the latest thing which is several hundred dollars a can,the size of which I don’t yet know.They are kindly making enquiries on my behalf.Questions as follows.

Will I have to do polystyrene on the roof /ceiling internal space or the walls as well?

As it is at the moment full of wood etc I have simply covered it over with a thick butyl sheeting building type cover, and am anxious to keep the work as limited as possible appearance is not important as functionality is what I am looking for plain and simple.

With regards the paint on stuff I don’t mind paying the huge sum if it works and thinking about quantity I might need several tins so please help me with suggestions and preferably if you have used it or know someone who has.Old fred my palm used a paint on stuff in the 60’s but things have improved since then any advice I would be most greatful.I won’t be able to proceed till the better warmer weather as I suppose it will need to be suitably drioed first before I can apply anything to it please let me have your thoughts.Alistair

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

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

20 replies so far

View Kazooman's profile


1064 posts in 2005 days

#1 posted 02-25-2013 04:12 PM

I think you really need to address where the moisture is coming from. Are you storing green wood to dry it? Is there a floor in the shed or is it just bare ground? You need to work to eliminate or at least reduce the source of the moisture in addition to any insulation you are going to do. You may need to increase the air flow with some vents.

View johnstoneb's profile


2967 posts in 2225 days

#2 posted 02-25-2013 04:17 PM

moisture condenses on a surface when that surface is colder than the air carrying the moisture. You need to ventilate the building and move the moisture laden air out or remove the source of the moisture. What is the moisture content of the lumber that is in the building? Before spending money on a paint that I don’t think will do anything try ventilating the building. Set a fan up to move the air through the building. You’ll need a vent on the far side of the building. so the air can move through. The polystyrene might reduce the condensation. I your climate is pretty humid. If the ventilation doesn’t work you might have to set up a dehumidifier.
you post sound like you want to eventually use this space for a shop. Insulation on the ceiling will just move the probelm to the walls. You will need to insulate fully and apply a good vapor barrier before finishing the interior walls.

-- Bruce, Boise, ID

View SCOTSMAN's profile


5849 posts in 3638 days

#3 posted 02-25-2013 04:29 PM

No I bought this kit shed and built it simply by screwing all the premade steel panels together onto a wooden base which I had made.

I as said do NOT intend to use it at anytime for working from just plain and simply use it for woodstorage nothing else.I have a bit of ventilation at the front and backside of the building but we have had some very cold weather inc snow ice frost etc.
The shed is simply warmer inside than the outside colder air and being steel it imediately turns the warmer air inside as it hits the roof and to a lesser extent walls turns to condensation the water is dripping from the roof ont a sheet I placed their for protectiing the wood beneath it from the water dripping above.This will get better when the warmer weather comes and we don.t have any cold outside to condensate the warm air inside just like your car on a cold day. Alistair

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

View Monte Pittman's profile

Monte Pittman

29554 posts in 2390 days

#4 posted 02-25-2013 04:34 PM

Probably should insulate to stop condensation. I am not sure where you are located, but if it is a high humidity area, this will be tough to stop altogether.

-- Nature created it, I just assemble it.

View Dbear's profile


14 posts in 1969 days

#5 posted 02-25-2013 04:40 PM

Couple of questions first;

Concrete or dirt/stone floor? An open floor will constantly be a source of moisture that migrates to the roof of your building. At the very least you would need some HD polyfilm vapor barrier over bare earth and a layer of sand or stone to help stop the migration of moisture. Best bet is a vapor barrier and insulation under concrete.

Without any vapor barrier under the floor or insulation on the underside of the roof the temperature fluctuations will cause the condensation of moisture on any cold surface when the temp gets above freezing. Just a matter of physics. Moisture always travels from a warm surface to a cold surface.

Best for wood storage: open air but under cover (lean-to type shed) and “stick” the wood, closed space but ventilate mechanically again with “sticking” or an insulated, heated space.

An open air, lean-to shed attached to your main workshop is easy to do. just provide some good vetilation and try to keep water from running through it. A concrete floor with vapor barrier is almost a must.

A closed space, such as your metal building will have to have vapor barrier/sand/stone and or a vapor barrier/solid floor plus some way to keep air moving through it to dispell the moisture.

As to heated space, you can heat a well insulated space with overhead gas fired radiant tube heat for pennies a day. I have a 24×40 well insulated pole barn with 35,000 BTU tube heater . I keep it at 60F for about 50 cents a day. Radiant heat heats the objects in the room and not the air so a building full of wood with a concrete floor would heat real cheap after everything gets warm.
The outdoor wood fired boilers are great too but only if you have a “Cheap” source of wood and tending it isn’t a problem. This type of heat source is great for under floor radiant which can also be supplied by a gas or electric micro boiler/pump system. Gas/electric is expensive for equipment but easy to install initially. Retro fit is problematic for an existing floor. Just make sure to use glycol for your transfer medium and not water. With water, if the power goes out or you loose your heat source you can have major issues with freezing the system and breakage of componenets. Not pretty and very expensive to repair.

I did alot of research when I was putting together my building. I went with the overhead gas fired radiant tube heat, best bang for the buck. Hope this helps.

-- Mark

View Porchfish's profile


832 posts in 2585 days

#6 posted 02-25-2013 04:46 PM

Alistair, I think any potential solutions will have to be considered carefully with the understanding that potential solutions will only be valid for a given climate. What will work in my environment,(North Florida) may not be worth a tinker’s damn in Scotland. As example, the moisture condensation would be worse in the summer here , than in the winter. That would be just the opposite for your situation, I think ! A friend with a similar problem here in our neck of the woods used enlarged shutters at both gable ends of his 12’x24’ wood storage metal building with automatic temperature sensing shutters at the high gable ends with a 1/4hp fan at one end blowing out. He installed a drop ceiling of wood runners hung by thin stainless wire and eyelets and poly foam drop in panels. he left 6” open space in each end of the drop ceiling to draw some air up from below. For more than two years now the arrangement has been perfect in preventing the collection and dropping of moisture from the metal roof and wall condensation. His lumber storage building is working quite well…BUT this is North Florida and I am sure conditions will not be the same as yours in beautiful Scotland ! I am not familiar with a condensation preventin paint, but good luck and let us know what works for you ! P.S. Bob (my friend here) found a greenhouse growers supply Co. and got a lot of good advice from them on vents, louvers, fans, poly-foam etc. and equipment and supplies, and advice on condensation and air movement. I am using them (Greenhouse Supply) for ideas for building a solar kiln for drying lumber that I hope to attach to the back of my garage/shop that can be opened to my work area in the winter to add solar heat to a limited area…......Hell…... Let’s all have fun !

Your North Florida friend, don s.

-- The pig caught under the fence is always the one doing all the squealing !

View Jim Finn's profile

Jim Finn

2661 posts in 2974 days

#7 posted 02-25-2013 04:47 PM

I would run a fan in there 24/7.

-- No PHD just a DD214 and a GED Website>

View SCOTSMAN's profile


5849 posts in 3638 days

#8 posted 02-25-2013 04:47 PM

Wooden floor as said no exposed dirt, I live in Scotland near the sea by the holy loch Dunoon argyll. Anyway these steel sheds are notoriousin the UK for condensating however probably most of the year it will be free from condensation it just happens when it’s very cold outside so most of the year it will not be a problem. so I am too late to save it from happening thgis year but might protect it for next winter with some money and some work and a little help from my friends LOL Alistair

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

View johnstoneb's profile


2967 posts in 2225 days

#9 posted 02-25-2013 05:05 PM

Part of your problem is that wooden floor. If you can this summer take it up and put a vapor barrier under it. That will stop the movement of moisture from the ground up through the floor.

-- Bruce, Boise, ID

View PASs's profile


595 posts in 3151 days

#10 posted 02-25-2013 05:43 PM

I DON’T live in Scotland…but I got a steel shed a few years back, mostly for yard stuff.
I decided to put some wood in it to dry a couple years ago.
As the shed has no ventilation, i.e. no place for the moisture to go, I got a couple of louvered crawlspace vents and put those in, one on each side of the shed.

As for paint, I’ve had great success using elastomeric paint, similar to that sold for repainting mobile homes, as a good roof paint on metal. It is flexible and can expand and contract with the metal.

Been to Scotland a few times while in the Navy.
Really enjoyed it.

-- Pete, "It isn't broken, you just aren't using it right."

View Howie's profile


2656 posts in 2975 days

#11 posted 02-25-2013 08:16 PM

I would start with adding some ventilation(as others suggested) and go from there. Might be all you need.

-- Life is good.

View Shawn Masterson's profile

Shawn Masterson

1325 posts in 2001 days

#12 posted 02-25-2013 11:40 PM

I would look into a roof power vent with a thermostat / humidistat. It will some on when it’s hot or humid. if it’s cold but humid it still comes on. something like this should do the trick

I know you are not in the states, but I am sure you can find something like this.

View Dennisgrosen's profile


10880 posts in 3168 days

#13 posted 02-26-2013 12:09 AM

may I surgest you recycle a few popcans … (actuly alot ) and a fan from a scraped PC
a few boards of wood , etc.
use it to make a solar to air heater ….. that shuold do the trick :-)
there is some vidio-clip of it on you-tube

here you can see two comercial type of it
sorry its on Danish but the one I think of its the one on the wall of the red house
it has been sold here the last ten years or so for keeping the moistier and saur smell out
sommervacation houses and basements

take care

View gfadvm's profile


14940 posts in 2742 days

#14 posted 02-26-2013 04:24 AM

I had a bad moisture/mildew problem in my tackroom in the barn and put an oscillating fan in there and ran it 24/7. Fixed my problem but yours may be totally different.

-- " I'll try to be nicer, if you'll try to be smarter" gfadvm

View woodbutcherbynight's profile


5241 posts in 2461 days

#15 posted 02-26-2013 05:58 AM

Try a small fan, and two to four incadescent 75 watt bulbs, run the fan on a timer leave the bulbs on all the time. See how this works after a week. If the problem gets better improve this design as it is less costly and you wrote you did not use the building for much else. If it gets worse consider drying this building in and putting a vapor barrier as others mentioned under the floor. I keep the florescent lights on in my shop all winter to help maintain a constant 50F or better temp in the shop when I am not in it running the heater. The incadescent lights put off more heat and are easier to build a temp test unit as you can use an extention cord for a few days to see how it works. The fan can be a cheap box fan.

-- Live to tell the stories, they sound better that way.

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