Garage insulation

I'm buying a house with what I believe is a not insulated attached garage. It is a three car space that I will try to utilize as a work space most of the year, but during the coldest of months, I won't be out there unless I can scab together some money for a big gas heater.

The house was built in 2006. It has an insulated foundation, gas heat, and insulated garage roll up doors. The ceilings in the garage are high and I could install a small lift if I wanted down the road. The inspection revealed that the ceiling of the garage wasn't insulated so I assume that only the common walls are not. Walls are drywalled and taped. Blow in, rip down and batts? Do I need a vapor barrier? I am in the frozen tundra of MN.

Go hive mind.. Go..

Blown in would be much better than ripping down the drywall. Less work, cheaper, more effective insulation. Make sure they poke test holes to verify insulation has made it all the way down the wall.

A garage built in 2006 with good insulation and insulated doors should be pretty easy to heat. If I was doing it, I would put in a vented gas heater. Salamanders (kerosene heaters) or other unvented heaters suck because you have to leave a door or window open to keep fresh air available so they have to work 10x harder than a vented gas heater. Are there gas lines near the garage? Find a good plumber that charges time and material (NOT book rates) and I bet you can get a gas line in there for a few hundred bucks. My last garage had a Reznor ceiling mounted vented gas heater and was totally uninsulated but the Reznor could get it up to comfortable temp (for me that's ~45-50 in the winter) in no time.

You could find a used Reznor (get a small one!) or even a used furnace from a remodel for very cheap. If you manage to get a high efficiency furnace for cheap, it's ventable through the sidewall using PVC piping. That's how I would do it, saves on the attic penetration.

I guess I should have asked - what's your budget? Because I've just spent a grand or two for you if you're buying new. ;-)

Is there an accessible attic above the garage?

You can fairly safely assume that there are 2 sides of the garage that are insulated--the door and the side(s) against the house. The next step, probably the most important step, is going crazy on the attic insulation. Probably batting, then blown in cellulose on top of it.

mtn wrote: Is there an accessible attic above the garage? You can fairly safely assume that there are 2 sides of the garage that are insulated--the door and the side(s) against the house. The next step, probably the most important step, is going crazy on the attic insulation. Probably batting, then blown in cellulose on top of it.

Yes. It is open and easily accessible. Do I do a vapor barrier in the attic?

Fueled by Caffeine wrote:

mtn wrote: Is there an accessible attic above the garage? You can fairly safely assume that there are 2 sides of the garage that are insulated--the door and the side(s) against the house. The next step, probably the most important step, is going crazy on the attic insulation. Probably batting, then blown in cellulose on top of it.

Yes. It is open and easily accessible. Do I do a vapor barrier in the attic?

I do not know that--I know you have to worry about the soffits being vented, but I really don't know what that means. My dad just did a ton of research on this and was telling me about it--apparently re-doing the insulation (replacing all batting and then blowing in cellulose) saved him more than the new windows he put in.

In reply to mtn:

Yeah, I know I need to the insulation baffles and to air seal any penetrations, but this vapor barrier stuff is new to me..

Dont sweat the vapor barrier, you can apply PVA paint (already likely there if its drywalled) that will be your vapor barrier.

Attic will need to be vented if its not already, cutting holes in the bird blocks, and venting with roof jacks or ridge vent at the top.

I think blown in will be the best bet, you get a little more R value and its reasonably easy since its already drywalled. I also second the reznor, those things are awesome if you have a gas supply. I have a pellet stove in my garage, works well, but takes a long time to heat up, but it only requires a plug and a hole in the wall for the flue.

Rightly or wrongly there's no vapor barrier other than the plastered (the builder apparently liked plaster, no idea) sheetrock in my garage.

Walls were insulated (w/vapor barrier), along with insulated doors. Blown in cellulose above. I'm located in Iowa-- it gets cold during the winter.

If you've got sufficient height, and can swing the cost (which wasn't extreme) I highly recommend burner tube type radiant heat. I've got 10 1/2 foot ceilings with the heater along the back wall and the reflector angled out into the room.

Nice thing about the radiant heat is that it doesn't blow dust around, doesn't create a bunch of hot air that all rushes out when you open the doors, and once you fire it up, you approach hot if you're in direct line to the heater.

Once you have it insulated, consider a waste oil heater. I built one. I no longer have to carry my used motor oil down to the store to get rid of it. Goes right out the chimney as CO2, the molecule around which life revolves, and my shop gets heated.

Spray foam insulation and a radiant tube heater. Life will be good. The spray foam does a great job of keeping the noise inside the shop so that the neighbors have little to complain about. The IR tube heater takes the place from just about freezing to comfy warm in about 15 minutes.

For the walls, do cellulose. Fiberglass chops up like cotton candy and "sticks." Its too light and whispy. You'll find that it is almost impossible to get full wall fill. It will drop down and hit a pipe, wire, box, or even a cobweb and stop, leaving the rest an empty cavity. Cellulose goes in like tiny little balls of pocket lint and almost ensures a complete fill. I prefer fiberglass for ceilings, but there is no need to switch machines and materials, just get a little more cellulose. I forget the R-value per inch, but they give you a little yardstick with the machine. Expect about 15% more cellulose per R-value compared to fiberglass.

If you have vented soffit, make sure it stays open. The easiest way to do that is to buy a roll of cardboard, freezer paper, or tyvek and staple it to the bottom of the rafters to make a short wall. Make the "wall" the same height as your target insulation depth for an easy depth gauge. I also like to use a sharpie or a can of spray paint to mark the trusses at the same depth, that way you're not pausing to check depths all the time. Just blow in cellulose until you get it as high as the lines.

As far as vapor barrier is concerned, the wall should have it regardless of not having insulation. Being built in 2006, it was most likely required by code. Whether or not you're in an area with strict inspections is unknown. If the walls don't have vapor barrier, skip it. The attic would have had faced batting if they had insulated it, so it probably doesn't have any vapor barrier. The easy button there would be to roll in some faced batts first. That wouldn't cover the joist faces, but it is accepted practice for retrofitting insulation.

If I were doing it, I would roll out faced batts in the ceiling (just some thin stuff to get the vapor barrier), then blow cellulose in the walls, then blow cellulose in the attic.

You can also cut into the walls to look for vapor barrier, but even if its not there, I wouldn't tear out drywall just to add it.

If you're going to do anything in the walls like adding electrical outlets or switches or running now plumbing, do it before you fill the walls with insulation.

I also agree on radiant heaters. Don't heat the air, heat surfaces. Heating the air will just cause convection to sap the warmth out of the air into the floor and walls. Heat you instead. 1000w of radiant heat will go farther in a garage than 4500w of those radiator space heaters.

I had three of These IR heaters in my loft in LA. That place had floorboard electric heat, 240v, 60A worth of breakers. So conservatively it was using 14,000 watts, but the fact that it was a breezy barn with floor to ceiling windows, exposed roof, and brick walls, the best it could do was a couple degrees warmer than outside at best. I put three of those running on 500w; one over the bed, one over the couch, and one over the kitchen. It didn't raise the air temperature, but it kept me toasty warm while only using 1500w.

mtn wrote: Is there an accessible attic above the garage? You can fairly safely assume that there are 2 sides of the garage that are insulated--the door and the side(s) against the house. The next step, probably the most important step, is going crazy on the attic insulation. Probably batting, then blown in cellulose on top of it.

This! I have an attached garage with one whole side and 2/3 of another sharing a wall with the house so they are heated and insulated. My garage door is as well. So the only wall not insulated is a south facing wall. I have 9-10 inches of fiberglass insulation in the ceiling with all walls & ceiling drywall covered.

I live in the Chicago area and the garage never gets colder then 30-32 deg. unless it gets below zero and that doesn't happen that often where I live, and not for long when it does. I can run a torpedo kerosene heater for 30-50 minutes and get the garage up to 60+ degrees. I also don't open a door and have no issues with CO build up. I usually shut the heater down and run a propane 10,000 BTU catalitic heater to maintain the temp in the garage.

If you do nothing else insulate the ceiling with as much insulation as you can fit/afford. The higher the ceiling you have the more important it is to retain the heat that floats up to the top of your garage.

jimbbski wrote:

mtn wrote: Is there an accessible attic above the garage? You can fairly safely assume that there are 2 sides of the garage that are insulated--the door and the side(s) against the house. The next step, probably the most important step, is going crazy on the attic insulation. Probably batting, then blown in cellulose on top of it.

This! I have an attached garage with one whole side and 2/3 of another sharing a wall with the house so they are heated and insulated. My garage door is as well. So the only wall not insulated is a south facing wall. I have 9-10 inches of fiberglass insulation in the ceiling with all walls & ceiling drywall covered. I live in the Chicago area and the garage never gets colder then 30-32 deg. unless it gets below zero and that doesn't happen that often where I live, and not for long when it does. I can run a torpedo kerosene heater for 30-50 minutes and get the garage up to 60+ degrees. I also don't open a door and have no issues with CO build up. I usually shut the heater down and run a propane 10,000 BTU catalitic heater to maintain the temp in the garage. If you do nothing else insulate the ceiling with as much insulation as you can fit/afford. The higher the ceiling you have the more important it is to retain the heat that floats up to the top of your garage.

Another Chicago guy, huh? Whereabouts are you?