New build with interior moisture problems

[libertarian]

I recently completed a 40x40 workshop with 10' 2x6 stud walls, w/ 1" closed cell foam flash coating on walls and 5" of cellulose. Ceiling has 12" of cellulose. Interior is drywalled. Have 2 insulated garage doors and 5 double pane windows. 5" slab floor (no insulation). I recently installed a 100k sterling propane heater with a separate combustion chamber vent (fresh air is pulled in and heated from outside). I am experiencing condensation on the inside of the windows anytime I heat my building up, I am located in southern Michigan where we have wild swings in the weather. Is my building envelope too tight? What do I need to do to eliminate the condensation? Do I need some sort of air exchanger? Should I make the intake for my heater and make it pull air from inside the building to solve this problem? I am looking for a simple solution. Thanks in advance for your help.

 

[p_mori7]

Are they single pane or dual pane windows ?

 

[dlenkewich]

If you aren't heating the building full-time and are having cold snaps, the moisture is from the constant cooling and heating of the air inside the building. The building just being completed doesn't help either.

If it's an option, I'd just leave the heat on at a "sweater" temp through-out the cold season - I'd be willing to bet that should take care of the excess moisture.

 

[Vicegrip]

I recently completed a 40x40 workshop with 10' 2x6 stud walls, w/ 1" closed cell foam flash coating on walls and 5" of cellulose. Ceiling has 12" of cellulose. Interior is drywalled. Have 2 insulated garage doors and 5 double pane windows. 5" slab floor (no insulation). I recently installed a 100k sterling propane heater with a separate combustion chamber vent (fresh air is pulled in and heated from outside). I am experiencing condensation on the inside of the windows anytime I heat my building up, I am located in southern Michigan where we have wild swings in the weather. Is my building envelope too tight? What do I need to do to eliminate the condensation? Do I need some sort of air exchanger? Should I make the intake for my heater and make it pull air from inside the building to solve this problem? I am looking for a simple solution. Thanks in advance for your help.

Is this a single pass direct fire or isolated combustion chamber heater?

 

[Frank The Plumber]

If you aren't heating the building full-time and are having cold snaps, the moisture is from the constant cooling and heating of the air inside the building. The building just being completed doesn't help either.

If it's an option, I'd just leave the heat on at a "sweater" temp through-out the cold season - I'd be willing to bet that should take care of the excess moisture.

Yup, run the heat at 45 and if you can, install a dehumidifier in the space, dry that air out and it won't rain in your shop.

 

[tdkkart]

How old is your floor?? Concrete sheds moisture for a LONG time and can cause problems alike you describe.

And yes, bouncing the temp up and down will also cause issues.

 

[Hit-By-Thunder]

yup, if the pad is new, that is most of the problem.

I put a hydrometer/barometer/themometer trio in the garage. Moisture is at 100% and the moisture is freezing to the door

 

[Grumpy365]

yup, if the pad is new, that is most of the problem.

I put a hydrometer/barometer/themometer trio in the garage. Moisture is at 100% and the moisture is freezing to the door

You are using bad instrumentation. You don't have 100% RH.

To understand sweating, you have to understand relative humidity and dew point.

Dew point is a measurement of the actual moisture in the air. Dew point is not relative to the temperature.

Dew point is the temp moisture begins to condensate on a smooth surface.
You take the dew point and the temp to determine the relative humidity.

The temp of your door & places where the moisture is forming is under the dew point of the space.

So you have a 35degree dew point in your shop and your door is 20 degrees it is going to sweat.

The only 2 solutions are. 1. Heat up the door over the dew point OR. 2. Bring down the dew point in the space to below the temp of the door.



A common way to bring down dew point is to run an AC coil. The water condenses on the coil and runs out a drain & is therefore removed from the air. This is what keeps your house dry in the summer. When controlling humidity, it is common to cool the air down to the desired dew point and reheat it to be comftorable.

Your dew point is going to be to cold to do this. ^^^. (dew point cannot exceed the temp).

They make desiccant dehumidifeirs, but they are energy HOGs.


I know none of this info helps you fix your problem, but I hope this helps you understand what's going on anyway.