Detached garage insulation And venting recommendations

[saleen21]

I have 24’x24’ detached garage. There are no vents anywhere. Getting ready to drywall ceiling and not sure if I should install fiberglass batts or blow in insulation. First I was thinking fiberglass batts and install them before drywall is installed, then I’m thinking blow in insulation after drywall is installed. As far has vents, can’t find any info on how many soffit vents I need to install. Would 4 on each side of garage be suffice. Than for roof venting. Better off with gable exhaust fan or install roof exhaust fan?

I’ve been googling all day and more I read more back and forth I go and than it starts getting confusing. Any suggestions please

Thanks in advance.

 

[bdbecker]

Here's a post from my build thread that goes into detail on the issue of attic ventilation. Lucky for you, I also have a 24x24 garage.

https://www.garagejournal.com/forum/showpost.php?p=7217689&postcount=402

One thing to note - when I was re-doing my roof, we used the whole roll of vent material, which was overkill for my space. Its not an issue as long as you have enough intake to support it. For your garage, as long as you hit that 150 square inch number as a minimum, you'll be good to go.

There was also a good thread that recently discussed the pros and cons of insulating before or after sheeting, as well as batts vs. blown-in.

https://www.garagejournal.com/forum/showthread.php?t=442277

 

[Randy in Maine]

If you use spray foam there is nothing to vent.

 

[saleen21]

According to the formula I only need 8’ of ridge venting
(24’x24’=576’/300 = 1.92 min sq/ft NFVA
1.92 / 2 x 144 / 18.0 = 7.68 min lineal feet of ridge vent. The 18.0 is how many sq/in of NFVA per lineal feet of the cobra 4’ ridge vents at HD.
Not sure what that equates to for # soffits required per side.

https://images.homedepot-static.com/catalog/pdfImages/a1/a1af46ec-75bb-47f4-bed0-46b65fe71a1f.pdf

 

[Toyomech]

location matters regarding insulation questions. Where are you located?

 

[bdbecker]

Your soffit vents need to have the same or greater surface area as your ridge vent.

 

[DaDuck]

I would not use drywall.....too much temp swing in a detached garage unless you plan on keeping it continuously heated and/or cooled for a full season. Drywall joints WILL crack with temp swings. My Son-In-Law just recently insulated and covered the walls with plywood (no joint filler) and then spray painted it White. Looks good and no worry about the cracks. Plywood will hold up over time better than drywall.

 

[saleen21]

Oh sorry I’m in Louisville KY, which I believe R38 is recommended. Weather here is the most unpredictable. Today it was 50, Friday it will be in the teens. Temp here in winter can be 70 one week and below zero the next.