I have recently built a 30 by 50 pole building with metal roof and siding. The roof has bubble foil insulation between the steel and roof purlins. The siding has tyvek between it and the 2 by 6 girts. I have r19 fiberglass insulation installed between the girts. We just recently poured the slab about a month ago and had our garage doors installed. We are running radiant heat in the slab to heat the building. Now that the building is all heated up I have condensation on the inside of the roof and also on the tyvek under the insulation. Any input or advice on what can be done to solve the problem would be much appreciated. I have not done any finish walls yet. I am located in new England so it is getting pretty cold here. Thanks everyone.
You are using an out of date browser. It may not display this or other websites correctly.
You should upgrade or use an alternative browser.
You should upgrade or use an alternative browser.
Metal roofing and siding condensation. Help!
- Thread starter Rich24
- Start date
readhead
Well-known member
Are you parking cars in there with snow on them?
Alan Douglas
Well-known member
Considering that it takes concrete a month to completely cure, there must still be moisture in it?
I park two large trucks in the garage but neither were wet when the went in before today's heavy rain. When we first poured the slab there was heavy condensation inside but it only lasted for a day of two so I thought we were in the clear. I know the concrete doesn't cure that fast so maybe it has something to do with it.
SGKent
Banned
I'd think concrete curing. Open the door a little and circulate some air. The higher the humidity the higher the dew point. Lower the humidity and it may not condense at all.
The Boss
Well-known member
How quickly did you put the heat in the floor and what is it set at? Did you put a vapor barrier under the slab? Is the ground around the garage wet?
cyamaha2007
Well-known member
A small box fan on 24/7 solved my condensation issues.
Lurch67
Well-known member
A small rotating fan in my basement on a timer, reduced/ mostly eliminated my humidity problem.
Thanks for the input guys. I waited almost 2 weeks after pouring the slab to start heating and brought the temp up slow. It is about 60 degrees in the shop. I was planning on doing some ceiling fans in the future anyway so looks like it will be sooner rather than later. Hopefully it will help. Until I get the ceiling fans installed I'll try a couple box fans.
Big Bad Dad
Well-known member
Do you have a ridge vent or gable end vents? Ventilation is crucial to keep a metal skinned building from sweating inside.
Considering that it takes concrete a month to completely cure, there must still be moisture in it?
Generally speaking, water doesn't leave concrete during extended curing, but is "used up" in the hydration process. The condensation is likely from something else.
Bob
My barn is 44 x 80 x 14 and I have 2 large 96"dia Big *** Fans. I run them on low 90% of the time and on high in the summer to just get the hot air moving. I have epoxy painted floors and in the if I just mop up after my truck or trailer thaws (and leaves 5-10 gallons of water on the floor) the floors dry in no time and the area stays low in humdity.
Even a few High Output floor fans will do wonders.
As for adding gable vents I think that is counter productiive to the ridge vent. The ridge creates negitive pressure in the building causing you soffits to draw in fresh air. This makes for a nice even air flow and the gables will just decrease the soffit flow. Just me $.02.
Even a few High Output floor fans will do wonders.
As for adding gable vents I think that is counter productiive to the ridge vent. The ridge creates negitive pressure in the building causing you soffits to draw in fresh air. This makes for a nice even air flow and the gables will just decrease the soffit flow. Just me $.02.
I agree, use one or the other type of vent. Using both ridge and gable style will more or less disturb the design flow of the other style. I have thought of installing a copula with a vent fan in conjunction with ridge vents it to increase air flow from the soffit up the rafters if need be.
Alan Douglas
Well-known member
If I'm reading this page properly,
http://www.cement.org/tech/faq_moisture_content.asp
About half of the total water is chemically bound.
http://www.cement.org/tech/faq_moisture_content.asp
About half of the total water is chemically bound.
If I'm reading this page properly,
http://www.cement.org/tech/faq_moisture_content.asp
About half of the total water is chemically bound.
There's lots of variables that complicate the issue. It only takes a quarter pound of water to hydrate a pound of cement as the chart shows, but the mix is unworkable at that w/c ratio unless superplasticizers are used, so a w/c ratio of around .40 to .45 is usually used for 3000 psi mixes.The higher the w/c ratio, the more water remains unused. Using a .42 w/c ratio, 5 sack mix would give a mix with about 200 lbs total water. Of that, about 50 lbs would be needed for hydration, and the remainder would probably be lost immediately as bleed water or evaporated. Not much would be lost once concrete reaches initial set/loss of plasticity. I wouldn't completely eliminate moisture rising from the surface of a curing slab as a form of condensation, but I'd say it's highly unlikely after a couple of days unless the slump was unusually high. A simple test is to tape a square of plastic film to the slab surface and watch for condensation. Of course, for the test to be valid there has to be an effective vapor barrier under the slab.
Bob
My barn is 44 x 80 x 14 and I have 2 large 96"dia Big *** Fans. I run them on low 90% of the time and on high in the summer to just get the hot air moving. I have epoxy painted floors and in the if I just mop up after my truck or trailer thaws (and leaves 5-10 gallons of water on the floor) the floors dry in no time and the area stays low in humdity.
Even a few High Output floor fans will do wonders.
As for adding gable vents I think that is counter productiive to the ridge vent. The ridge creates negitive pressure in the building causing you soffits to draw in fresh air. This makes for a nice even air flow and the gables will just decrease the soffit flow. Just me $.02.
911 Mike is correct. Use one type of venting system or the other. Actually soffit in combination with a ridge vent is the most effective passive system. Gable vents are a thing of the past. There are much better alternatives.
Check out this article.
What R-value is that bubble insulation? Is that the only insulation in the roof?
Most likely you have warm moist air coming in contact with colder air. Colder air cannot hold the same amount of moisture as warmer air so the moisture condenses out of the air; hence the condensation you see.
Last edited:
"Most likely you have warm moist air coming in contact with colder air. Colder air cannot hold the same amount of moisture as warmer air so the moisture condenses out of the air; hence the condensation you see. "
This is usually the first reply in these threads.
This is usually the first reply in these threads.
power wagon
Well-known member
"Most likely you have warm moist air coming in contact with colder air. Colder air cannot hold the same amount of moisture as warmer air so the moisture condenses out of the air; hence the condensation you see. "
This is usually the first reply in these threads.
the right answer