Metal Garage Ventilation

-
PA Dodger

PA Dodger

Well-Known Member
Joined
Jul 21, 2011
Messages
483
Reaction score
99
Location
Westminster SC
I had a nice 5 bay metal garage built a few years ago primarily for storage. I had the factory installed roll insulation installed when the garage was built. If there was a ridge vent, it can't be operational because I can see how the insulation was done across the roof. The garage is kept closed. Being in South Carolina, it never gets really cold but it will get hot in there. For security reasons, there are no windows in the garage. Should I add a gable fan to circulate air with maybe an air intake vent on the opposite end? Or will that cause problems from the humid summer air?
Thanks.
 
A couple of gable vents would do good at pulling heat out of the interior ceiling area, for some cross ventilation.


☆☆☆☆☆
 
They make solar powered attic fans.


Screenshot_20231112-235731.png
 
Last edited:
Dana67Dart said:
They make solar powered attic fans.
Click to expand...

I was looking at the solar powered fans. I thought they'd be a good idea to manage the heat of the day. I'm not looking for climate control. I was mostly concerned with drawing in more damp air.
Any idea if the make-up air should come from up high or down lower on the side opposite the exhaust fan?
 
Ridge vents are designed to work with soffit vents. You need a 2" air space above the insulation. That should be sufficient. Is there a problem?
 
Last edited:
I have a metal building, too. I plan on a gable vent on one end and an exhaust fan on the other. I think that would do it.
 
The air space for ventilation needs to be between the insulation and the roof. Any other design is beyond me.
 
PA Dodger said:
Any idea if the make-up air should come from up high or down lower on the side opposite the exhaust fan
Click to expand...
Don't know but a length of duct could make a gable hole ground level.

There are also exchanger type air inlets.

What they do is take in outside air, pass it over a heat exchanger if sorts that has the inside air passing through it.


Screenshot_20231112-234933.png

What it does is if the air in the room is cool but the outside air is hot, it cools the hot incoming air using the cooler inside air leaving the building.

If the inside air is warmer than the outside air it heats up the cold incoming air using the warmer inside air leaving the building.

It is an air to air heat exchanger.
 
Air humidity is related to temperature. If you heat air, the relative humidity drops, all things equal. But amount of water vapor present is the same.
Adding vent air won't really cause trouble in the summer unless you've got stuff in the barn which somehow gets below the dew point, which would cause water vapor to condense onto those cooler items.
Venting between the roof and the insulation helps you cool off the envelope and maintain a lower relative humidity.
It doesn't sound like your location/climate comes with a significant risk by just adding Gable vents. Considering most metal buildings are about as air tight as our cars (not at all), trying to vent between the roof and insulation is probably not worth the cost to setup such a configuration if your building currently has fiberglass sandwiched between the roof and framing.
 
The insulation is sandwiched between the roof and wall panels and the frame so no air gap for the ridge vent to be doing anything. I like the idea of a vent on one end and a fan on the other and then if that's not efficient at air movement I can do what Dana67Dart mentioned and put ductwork inside to bring incoming air in lower. Saves me from swiss-cheesing the building by trying different inlet vents.
Thanks all!
 
I've never seen a metal building that had any kind of roof ventilation if the faced roll insulation was installed in direct contact with the roof sheets.
 
I had a problem with a house I remodeled for my daughter. It had metal roof above laundry room and sheet rock ceiling with insulation on top of it. When it started sweating and dripping down on ceiling I got a friend that owns an insulation business to look at my problem. He said the way to stop it was to insulate the bottom of metal and since it wasn't a job big enough for him he sent me to Lowe's and got spray foam in bottle similar to freon bottle. It solved the problem, Joe
 
You must log in or register to reply here.
-

Back
Top