Keeping a garage warm: What would you do next?

[Rick Moyer]

Definitely ceiling first (heat rises!). I have a similar space. I was fortunate to have the garage walls and ceiling just studs when we moved in last year, so I was able to put in R13 faced on the walls and R19 in the ceiling. My G73 heater runs very little to maintain heat in there and can cook me out if I turn it up.
btw, my doors consume one wall and are also thinly insulated, but don't seem to be a factor. Make sure you seal any air leaks you can find. If you insulate both walls and ceiling, your heater wil heat that space well.

[Eric Gustafson]

Sherwin Williams and other manufacturers make a vapor-barrier primer that will do the job. You do not have to tear out the sheet rock!

Wisconsin tested using ordinary paint in 1978 and found it worked adequately, but now there are paints made just for the task,

http://www.fpl.fs.fed.us/documnts/fplrp/fplrp319.pdf

[George Bregar]

Sherwin Williams and other manufacturers make a vapor-barrier primer that will do the job. You do not have to tear out the sheet rock!

Wisconsin tested using ordinary paint in 1978 and found it worked adequately, but now there are paints made just for the task,

http://www.fpl.fs.fed.us/documnts/fplrp/fplrp319.pdf

The study was based on older homes with plaster/lathe on interior surfaces...and those primers are designed for interior use. IMO a garage, with a concrete floor, would see much higher moisture than an interior heated space. I would want a moisture barrier. I would tear off the rock, use faced batts, and rerock. Moisture in walls can rot framing...it's worth the effort that can be accomplished in a few hours.

[David Hostetler]

Vapor barrier or not, and direction of kraft facing varies by region, check your local codes, but I agree, fill that attic with kraft faced roll insulation, the thickest you can get in your joists. Mine will take R30, and I am in the middle of doing just that. Remember heat rises, the ceiling will be your greatest heat loss.

AFTER getting the ceiling taken care of, then you can start looking at other areas. I would make sure the doors are insulated, and sealed as well as possible. THEN worry about the walls...

[Ken Fitzgerald]

Augusto,

Get some bids from local contractors.

I had the ceiling in my shop blown in by a professional insulation company. It was cheaper than I could do it myself.

The walls I did.

[Augusto Orosco]

Augusto,

Get some bids from local contractors.

I had the ceiling in my shop blown in by a professional insulation company. It was cheaper than I could do it myself.

The walls I did.

I am gathering info on that front too, Ken. I called one yesterday. He mentioned $1,250 for R38 cellulose That's about 7c per square foot of R value (500sf area) and way off my budget!

I will call a couple more; but if they are all in that price range, I think I could do either the bats of the blow in myself for a third of that price!

[Thom Sturgill]

+1 on ceiling first.

For about the price you were quoted for R38 you could spray foam 3" @ R7/in. Not as high an R value but a better seal and no vapor barrier needed. There are several vendors that sell kits as large as 600bf for about $1.00 bf.

Assuming that you do not want to pull the ceiling drywall down and that the builder did not install a vapor barrier (he should have to keep fumes from entering the house) - If you put down batts or blown in, I woulds lay down plastic VB first, wrapping it over the joists, taping any joints, etc and make sure that soffit vents are not closed off with the kits they sell for that. Also pay attention to electrical boxes, inset lights, etc to make sure that they are properly treated (most will probably want insulation kept clear).

[Eric Gustafson]

I thought the 1978 study was interesting because they artificially elevated interior humidity to 35% and held it there. Hardly a normal condition, yet ordinary paint did better than expected. Unless you run a humidifier 24/7 or are in a area with a unusually high water table, do you really get internal humidities that high? I lived in PA during my youth, (dreary Erie mistake on the lake!) and I remember much drier conditions inside during the winter.
One of the notes in the study suggested that manufacturers should produce vapor barrier paints that could do the job better. Of course, that was a long time ago. In the ensuing years there are many such paints. A simple Google for vapor barrier paints will find many formulations that have the reccomended permeablity of less than one.

I would tear off the rock, use faced batts, and rerock. Moisture in walls can rot framing...it's worth the effort that can be accomplished in a few hours.

Ripping out and redoing sheetrock might be an easy "few hours" for a pro, but it is more like a few days to a week of really messy and exhausting work for an amatuer like myself. If you hire someone to do it, it can add a lot of cost to the project.
My suggestion was to give the OP an option that will get the job done cheaper and easier. Using blown in insulation and vapor barrier paints is one way to go. Vapor retarding paints are reccomended for existing construction in even colder climates by the US Dept of energy.
http://www.energysavers.gov/your_home/insulation_airsealing/index.cfm/mytopic=11810

[Augusto Orosco]

I thought the 1978 study was interesting because they artificially elevated interior humidity to 35% and held it there. Hardly a normal condition, yet ordinary paint did better than expected. Unless you run a humidifier 24/7 or are in a area with a unusually high water table, do you really get internal humidities that high? I lived in PA during my youth, (dreary Erie mistake on the lake!) and I remember much drier conditions inside during the winter.
One of the notes in the study suggested that manufacturers should produce vapor barrier paints that could do the job better. Of course, that was a long time ago. In the ensuing years there are many such paints. A simple Google for vapor barrier paints will find many formulations that have the reccomended permeablity of less than one.




Ripping out and redoing sheetrock might be an easy "few hours" for a pro, but it is more like a few days to a week of really messy and exhausting work for an amatuer like myself. If you hire someone to do it, it can add a lot of cost to the project.
My suggestion was to give the OP an option that will get the job done cheaper and easier. Using blown in insulation and vapor barrier paints is one way to go. Vapor retarding paints are reccomended for existing construction in even colder climates by the US Dept of energy.
http://www.energysavers.gov/your_home/insulation_airsealing/index.cfm/mytopic=11810

Thanks Eric, George and everyone else for all the helpful feedback!

I think it is clear to me now that walls should be the 'later' project. I will focus on the attic space first. Blow-in insulation sounds appealing, but there is no vapor barrier currently there, so I would have to add one (or prime the ceiling with the special paint Eric suggests). On top of that, I would have to make sure to keep the air flow near the sofits, for which I would have to install some of those rafter baffles on each soffit vent. I much rather avoid that, since that's a pretty hard area to reach.

So, even though it might be more expensive, it's looking to me that buying paper faced bats would end up being a simpler solution given my attic configuration. I can simply cut the bats short of the vent to take care of air flow and the kraft paper would take care of the vapor barrier issues. There are only two electrical boxes in the attic (for the garage lights), so it would be simple to cut around those, too.


P.S. The humidity in my garage has been between 60% - 70% ! (I don't get condensation on my tools, though, but I have to be careful with rust on my cast iron) I haven't checked the humidity levels inside my house; maybe I should. I live in a flood prone area, and every time it rains or the snow metls, my basement sum-pump gets hard at work.

[Ken Fitzgerald]

Augusto,

Check with your local building code department. Painting with a PVA primer was regarded as an acceptable moisture barrier here.

[Don Jarvie]

Just so I understand what you want to insulate. Is your garage ceiling flat so the attic floor would be the bottom of a triangle or do you have cathedral ceilings?

[David Hostetler]

Assuming price equality between markets, Home Depot lists 58.63 sq ft R30 batts for $44.56 (Kemah Texas). Assuming you need 500 sq /ft and go ahead and grab 10 packages of batts just to be sure you have enough to spare.. You are still under $500.00 for doing the entire attic over the garage.

[Augusto Orosco]

Just so I understand what you want to insulate. Is your garage ceiling flat so the attic floor would be the bottom of a triangle or do you have cathedral ceilings?

The former: My garage ceiling is flat (sheetrock). The attic floor is the bottom of a triangle (well, almost, I have a hipped roof).

The attic doesn't really have a 'floor'. It is just the joists supporting the structure (which is good, because it's open for insulation). There are narrower 1" wide wodden strips accross the joits that were used to secure the sheetrock. I can access the attic space through a 3x4' hatch using a ladder.

[Don Jarvie]

So all you have to do is lay the batts between the joists and leave a few inches at the end so you don't block the soffit vents.

I wouldn't worry too much about a vapor barrier since you have space between the attic floor and roof. If it was a catherdral ceiling you may want to consider the barrier.

Also it is more money but use the batts since it will be neater should you want to put some plywwod down and use the area for storage.

[William Schmitz]

The recommended order of business is to tackle air infiltration before insulation. There is quite a bit of information available on the internet for this topic, such as:

http://www.simplehomerepairs.com/Weatherproofing.html

This means caulk and weatherstrip. Especially as you plan to heat your shop from "cold" prior to use with a convection heater (heating the air, not the surfaces); if you don't keep the cold air from continuing to come in you will end up with a hot head and freezing cold feet!

In addition, insulate the ceiling as recommended here. Insulating walls is much more work, so save that for another year.

I suspect a reason you are getting your shop up to around 52 fast, then having trouble above that is that all your heat is rising above you and shutting off the heater (mounted high with an internal thermostat, I suspect). A remote thermostat should help with this, mounted at the level of the people.