Insulate detached garage or not?

[Hivolts]

All,

This is a detached 800 sq ft garage. I’ve Demo’d the old walls and ceiling. Now I’m on to a wall choice. I’m in Charleston SC. Not that cold, but yes hot in summer. Garage will have no heat, or AC. I also plan to leave the ceiling open since I like being able to get to storage up there.

Would it make any difference at all if I insulated the walls before covering? Pros and cons?

Thanks

 

[rsparks64]

If you are thinking about adding heat or ac later I would insulate those walls before covering with drywall, osb, etc. Then you would only have to do the ceiling/roof later. That being said, if you cover the walls w/o insulation it well help some in the winter if you do decide to use a little space heater while working in there, but probably not a whole lot. I have lived in cold weather places and hot weather places with no insulation and with partial insulation and would love to put AC in my current garage but it would be cost prohibitive to fully insulate the garage and add AC per my HOA's requirements. I do use a little electric Lesko type heater on occasion in the winter and use a fan in the summer. My recollections of Charleston are very hot and very humid in the summer, but not too bad in the winter.

 

[vavet]

How much do you like sweating and shivering?
20 years ago, I was just happy to be buying my first house in south Georgia - conditions not too different from Charleston. My requirement was a 2 car garage. I was a single guy and I wanted to garage my car and my workshop. It was not easy in that price range, but I did it....and I enjoyed it. I never would've thought today I'd have a dedicated 768 sq ft detached garage for a workshop with insulated walls and ceiling and a mini-split. Our priorities change as we get older. I tried it without the climate control and decided I was not having much fun working out there in the summer. I spent a few 1000 dollars to do it all, but now i have a building I can enjoy using 12 months out of the year.

None of the steps (insulation, drywall, or HVAC) are all that expensive, but when you add them up, they turn into a decent chunk. Some of my friends and neighbors with newer, nicer cars and trucks think my garage is a bit crazy, but I drive a 9 year old car with 117k miles. Their vehicles exceed the total value of my garage...so it's a matter of priorities.

 

[TractorJeff]

I would recommend insulating the ceiling after insuring it would have some sort of attic ventilation. Reasoning is most summer heat comes from the ceiling.

 

[XJSuperman]

800ish sq ft in Iowa and I wouldn't go without insulation, but in your climate Im less certain. If you are going to put sheet over the studs, then yeah, insulate it. Why would you not?

 

[rsanter]

If the heat comes from sun exposure, then insulate.

If the heat is just convection/conduction from outside temps, then it won’t help push if you are not heating/cooling the space

 

[BroncoRaider]

I just finished insulation and drywall in my detached garage. It was really cold last weekend, but quite comfortable in the garage. I expect the same case in the summer. I would insulate all the way up after ensuring you have ventilation. It will make a world of difference.

 

[Kev442]

If the sun shines directly on it, insulate it. Exterior wall could be hitting 115, interior wall will only be 75.
Insulation is good noise abatement too.

 

[Hivolts]

Copy all. Thank you.

Do I need the plastic between insulation and drywall?

Also, thinking I might put up the radiant barrier on top to reflex? Good or bad there? Even if I leave ceiling open.

Garage does sit in the Sun.

 

[b-boy]

It's amazing how much difference insulation will make, especially in the Summer.

 

[bdbecker]

It's amazing how much difference insulation will make, especially in the Summer.

Totally agree.

I don't have AC in my garage, but it is (mostly) insulated and it stays a good 10-15 degrees cooler than the ambient temp. Combined with dehumidifier, its way more comfortable working in there on hot, humid summer days than it ever was before I had it insulated.

 

[mepstein]

I'm currently insulating my 22x24 detached garage so I can heat, cool and dehumidify with a mini split. I'm using Rock Wool. Great stuff and I'll never touch fiberglass batt insulation again. It also makes things very quiet and since it's pressure fit, it helps with air sealing. Rock wool doesn't burn, doesn't hold moisture, mice and insects don't like it and goes up 10x easier than fiberglass so it's worth the small amount extra, at least to me.

Cons is the wall insulation will hardly do anything if you don't do the ceiling.

 

[Colin Len]

Personally, I feel like insulation is always worth it if you plan to spend any time in there and/or store anything of value in it. I live in one of the more moderate climates where temps rarely dip below 40deg or above 100deg. In my 1942 built, uninsulated garage it gets quite chilly in the garage in winter and is unbearably hot in the summer.

This past summer my wood bench top registered 116deg with a IR thermometer. The garage, and everything in it, was 15-20deg hotter than ambient air temp. This was simply because the sun bakes my garage and the whole structure will heat up then radiate that heat.

I'm desperate for the chance to pull everything out of my garage, insulate, run new elec and then finish the walls. With some luck, 2021 is the year!

 

[Badgerstate]

I would insulate. You may not be concerned with heat in Charleston but you probably are concerned with keeping it cool in the summer.
I live in Ohio and have an insulated detached garage and I love how its always about 20 degrees warmer inside the garage than it is outside, so I usually dont have to scrape my car windows and the garage is toasty warm even in the winter when I fire the space heater up.
As someone who lived in Wisconsin for 30 years with an uninsulated garage and often had to work on trucks and snowmobiles in a Carhart arctic suit with a propane heater blazing, its nice to have an insulated garage now.

 

[NUTTSGT]

You've already done the hard work, the easy part is putting the insulation in.

 

[Kev442]

Copy all. Thank you.

Do I need the plastic between insulation and drywall?

Also, thinking I might put up the radiant barrier on top to reflex? Good or bad there? Even if I leave ceiling open.

Garage does sit in the Sun.

I would do the vapor barrier too. Not sure about the reflect foil, I always wonder about shingle temperature with it.
I'm not seeing any hurricane strapping?

 

[rburke65]

Insulation is good....I would.

 

[laser3kw]

It's amazing how much difference insulation will make, especially in the Summer.

Fully agree with everyone. My 30x40 is insulate all around. It will maintain a 70° clear into July or August sometimes before the summer heat creeps in. I have to preface that by mentioning I do not have the doors open much. Just long enough to move something in or out.

 

[latebreak]

Insulation is good noise abatement too.

This is great reason. I can work later into the night and start earlier and compressors, impacts, etc make less of an impact to my neighbors.

 

[Mwaters]

Just finished up a 600sq ft detached right around Thanksgiving time in the Pacific NW. Insulated ceiling and walls; R38/R21 respectively. Baffles in the ceiling for airflow. It is about 48 degrees out today and inside it is at 54 with no heating installed. My little 1500 watt space heater will actually, albeit slowly, warm the place to around 60. Plans are for a 5000 watt ceiling mounted heater (currently on order) which will help warm the place up in no time. Definitely recommend insulating and drywall!

 

[lilredex]

I have a similar size, similar construction and insulated it. But before, I built out the studs to 2 X 6, and left the ceiling open. Makes a huge difference both summer and winter, for both heat transfer and noise.

 

[Slowbuilder]

How much do you like sweating and shivering?
20 years ago, I was just happy to be buying my first house in south Georgia - conditions not too different from Charleston. My requirement was a 2 car garage. I was a single guy and I wanted to garage my car and my workshop. It was not easy in that price range, but I did it....and I enjoyed it. I never would've thought today I'd have a dedicated 768 sq ft detached garage for a workshop with insulated walls and ceiling and a mini-split. Our priorities change as we get older. I tried it without the climate control and decided I was not having much fun working out there in the summer. I spent a few 1000 dollars to do it all, but now i have a building I can enjoy using 12 months out of the year.

None of the steps (insulation, drywall, or HVAC) are all that expensive, but when you add them up, they turn into a decent chunk. Some of my friends and neighbors with newer, nicer cars and trucks think my garage is a bit crazy, but I drive a 9 year old car with 117k miles. Their vehicles exceed the total value of my garage...so it's a matter of priorities.

^^^^^ This!!! You will be so sorry you didn't spend the (relatively) few dollars today if you cover it all up w/o insulation, fill the garage with stuff, and then decide it's too cold or hot to use. Consider it an ounce of prevention...

 

[Notgrownup]

I’m in eastern NC so not too far... I wasn’t sure if I was going to insulate my 24x24 but I did. I then decided to put a mini split and I’m glad I did. Similar to Vavet

 

[Hivolts]

Thanks for everyones response. I'll insulate for sure now.

Plan to use the Rock Wool.

 

[nadogail]

I would be more comfortable if I had insulated my garage after I bought the house.

But a combination of lack of finances and my personal ignorance kept me from insulating the garage prior to my nailing up the drywall.

Fortunately the climate here is very moderate.

 

[eastbaysubaru]

Thanks for everyones response. I'll insulate for sure now.

Plan to use the Rock Wool.

Good call. Rockwool is a great sound deadener and is almost always used around bathrooms for the sound deadening for the shower and *******. I think you'll be very happy with that decision.

-Brian

 

[Notgrownup]

In the dead of summer the cool nights is almost enough to keep it decent in the shop without the a/c on. But with the heat pump it’s the bump for sure.
I blew eco insulation from Lowe’s in my ceiling and it was the trifecta.