shop sweats

[LarryD]

You've explanined it the way I always thought it worked Eddie.

My shop is wood construction with no insulation. I've also got 18" x 18" vents in both gables.

On very high humidity days, particularly rainy days, the floor looks like it just got mopped. If I put my hand on the floor it feels very cool meaning the ground is cooler than the ambient air and moisture is pulled out of the air. The walls and roof don't "sweat" because the air surrounds them and they maintain a temperature closer to the ambient temperature.

If I had a metal shop, I would think insulation would be my first choice to relieve any condensation problems. Put a barrier between the different temperatures.

 

[Redneck_Randy]

Would inserting styrofoam panel cut to fit in between the metal stud on my shed stop the sweating? I was thinking of getting 1 inch thick panel from like Lowe's or Home Depot. Should there be a viod behind the styrofoam panels are should they be tight against the siding on the inside?

Thanks

 

[Dusty]

If the ground under the concrete holds moisture, the concrete being a porous material will wick the moisture to the surface when the temperature conditions are right. For this to happen, the air temperature has to be cooler than the ground temperature. Moisture in buildings is a difficult thing to remediate unless you understand all the varied conditions that are leading to this problem. Many times, it is a combination of factors all coming together at the same time that cause the problem. Different parts of the country have different weather patterns that provide for many of these issues. As an example, in the hangers in Lakehurst NJ where the dirigibles were once housed, clouds will form in the upper levels and then it will rain inside. I am certain that is a site to behold. Without knowing all the variables, it isn't possible to use one solution to cover all aspects of why this is happening. One thing is for certain, if the outside air is moisture laden, and that moisture laden air can find a way into the building, it will condense on the colder surfaces inside the building, unless the interior is heated and the metal inside the building is warm. The best solution is to keep the moisture out, and the heat in. If the building is never heated, then it will always sweat when certain conditions are met.

 

[Defective]

Would inserting styrofoam panel cut to fit in between the metal stud on my shed stop the sweating? I was thinking of getting 1 inch thick panel from like Lowe's or Home Depot. Should there be a viod behind the styrofoam panels are should they be tight against the siding on the inside?

Thanks

The panels will help, but not solve the problem. The big benefit with sprayed on foam is that it seals completely. The panels will allow moist air to get through at the seams.

If I were to insulate steel with panels, I'd put them tight to the steel, then apply a vapour barrier.

 

[Redneck_Randy]

The big benefit with sprayed on foam is that it seals completely.

Do you have any info (URL links) on the net for this spray on foam you used and how it is applied?

Thannks

 

[Defective]

Randy,

Just did a quick google search:

Spray Polyurethane Foam Alliance

Spray Foam Insulation

These two links explain it pretty well & probably give more information than you want...

When I had the shop roof done, I simply called around and found a contractor. He brought in a crew of 4 guys. They spent about 4 hours covering the contents of the shop with plastic and 2 hours spraying the inside of the roof. The only difficult part was around the chimneys & they simply cut the hardened foam back about a foot & filled the space with fire rated rock wool. IIRC it cost me about $2,000 at the time in a 28 x 40 shop.

 

[UPRAISER]

Condensation can be a real pain in some areas.

My father lived on the Oregon Coast which is about as wet as you can get. He found that running a small fan helped a great deal. I presume it helped to maintain the air temp. a bit more even. His shop was not insulated, he had a small wood stove that he fired up in the winter. He had some wet floors when the monsoon rain fell, so I know it was wet at times.

In his last years, the stove was never used, but the fan always ran.

He had some tools with cast iron tables and steel componets which usually will show rust if they are subject to a high level of moisture.

In any case, I have a lot of his tools and they were not oiled, or waxed, or even cleaned of sawdust etc. and they have no rust on them.



Curt

 

[Farwell]

The spray foam is more expensive, but in my opinion one of the better ways to insulate. The only problem I can visualize is if you need to remove one of the metal panels. Not sure what to do in that case.
I saw the foam after it was applied and before it was covered in an Amish store here in Michigan and it looked beautiful. The process is similar to spray painting and probably should be done by a pro. One inch foam will take care of most insulation needs as well as prevent moisture problems. If ya got the bucks I would go for it.
Farwell

 

[CTyler]

On the concrete sweating....it can happen both ways from the ground and from the air condensing on the surface.

The spray on insulation would be better, faster and eaiser but its $$$ like mentioned. I looked into it to add more insualtion than the R-7 that was installed. Went with rolls R-19 since I'm framing up the inside 2' OC and drywalling.

 

[Redneck_Randy]

I deided to go with the styrofoam panels from DOW. I'll be using the 2 inch panels. I'll cut them to pressure fit between the steal studs and also use a little silicone to help hold them in place. I'll aslo be having the electric finished in the shed this week or next week then I will install a gable vent fan.

Thanks for all the great info from everyone!