Keeping a garage warm: What would you do next?

[Augusto Orosco]

After getting my Dayton G53 electric heater (http://www.sawmillcreek.org/showthread.php?t=122266) , I am now looking for further improvements in my garage insulation. I can’t tackle everything this winter due to time and money constraints, so I am looking for the best bang for my time/buck.

It's a 2 car attached garage with 8' ceilings and about 500sf of total area. The garage walls are sheetrocked, but with no insulation (with the exception of the wall that is shared with the house). The ceiling is also sheetrocked, but the attic on top is not insulated. The two garage doors span most of the longest wall and are already insulated with a 1.75” thick rigid foam in between the metal sheets (pre-installed by the manufacturer).

Last weekend, temps went down to the high 20s and the garage was about 40F (without the heater being used). I fired up the heater and had the garage at 50F in about 15 min, but after an hour, it wasn’t getting much warmer than 52. It’s good enough for me to work, but now I am getting ambitious and thinking that 55-60F would be great!

So here is what I have currently in mind:

1) Garage doors: I could add some additional insulation on top of what they already have, but it doesn’t seem like the best first thing to do.

2) I could insulate the attic with some bat insulation. It would be an easy DIY project, and for the 400sf of area, I am probably looking at something in the $300 worth of 30R insulation. I am leaning towards doing this first.

3) I could blow in some insulation through holes in the un-insulated walls (about 400sf of wall area). I have no idea how to do it myself and probably would have to hire someone. Don’t know how much that would cost either.

If you can pick only one of those 3, which one would that be? Any ideas about costs? Any other alternatives I might be missing that would make a bigger impact?

Thanks!

[Baxter Smith]

Ceiling first. Then check the seal on the weatherstripping around the garage doors. They are the biggest draft area on my shop. Maybe they can be adjusted slightly to provide a better seal. If you don't have to open both all the times, you might even consider taping the joints with some magnetic tape where the panels meet. I put some magnetic weatherstripping around mine.

Those extra 5 degrees are nice! Good Luck.

[Lee Schierer]

I would insulate the ceiling first and then the walls. Most importantly you need to get rid of air flow. Any hole to the roof area will dump heat almost as fast as you can make it. Most rental places will rent blowers for blowing in cellulose insulation. It's not my favorite material, but is probably the least cost option for your sheet rock walls. You can also get spray in foam that provides superior insulation, but the cost may be out of your budget.

If you put batts in the ceiling, wear long sleeves and tape on gloves, wear a face mask and wash up with cold water first. Make sure you don't block off the air flow from the soffets through the eaves in the ceiling with the insulation.

[Mike Cruz]

I suppose I would do 2, then 3. One without the other won't really do the trick, IMO. But then again, either will help. I think the doors would be the third on the list.

Hey, take out the insulation on the wall that is shared with the house...rob some of that heat! :D

[Peter Aeschliman]

Definitely the ceiling first, no question. Way more bang for your buck there.

Magnetic tape- now that's a fantastic idea! That's the major remaining area I need to address in my shop and I was struggling to come up with a way to take care of it. Thanks!

[Bob Borzelleri]

Augusto...

The first thing I would do (and actually did) is spring for this:

http://www.google.com/products/catalog?oe=utf-8&rls=org.mozilla:en-US:official&client=firefox-a&q=infrared+thermometer&um=1&ie=UTF-8&cid=12955984420802696606&ei=NsInS9mxFISisgPavO3KDA&sa=X&oi=product_catalog_result&ct=result&resnum=2&ved=0CCcQ8wIwAQ#ps-sellers

I have used it for diagnosing heat loss throughout the house and the shop. It's the best option I can think of for prioritizing where to focus on heat retention/loss.

You can spend a lot on these things, but the one I refer to in the link is a good combo of fairly inexpensive and accurate.

Once you get over pointing it at the cat, the oven and boiling water, you can really get down to business and know exactly where you need to address heat loss in the garage and anywhere else. too.

...Bob

[paul cottingham]

Just out of curiosity, how much heat loss (or cold ingress) would you get from a floor deain that hooks into the perimeter drains? Would you need to do something about that?

[Augusto Orosco]

If you put batts in the ceiling, wear long sleeves and tape on gloves, wear a face mask and wash up with cold water first. Make sure you don't block off the air flow from the soffets through the eaves in the ceiling with the insulation.

One more question regarding the attic: Do I need paper faced or unfaced bats for this? The joists are around 36" on center (IIRC) and the sheetrock panels are attached to 1x2 wodden battens nailed accross the joists

[George Bregar]

One more question regarding the attic: Do I need paper faced or unfaced bats for this? The joists are around 36" on center (IIRC) and the sheetrock panels are attached to 1x2 wodden battens nailed accross the joists I would think they are 24" OC...but yes, paper faced. I would only go a standard R19 if you are cost conscience...this isn't a living space that is heated constantly. You can always blow in later. I would also just pull off the sheetrock on the walls, use faced batts, and then rerock. Doesn't cost much for two walls, and you really need a moisture barrier. Approx cost assuming two 24' walls: Drywall $60. Wall insulation (2x4) R13 Faced= $90

[bruce buren]

ceiling, with blown in

easy diy and free machine with insulation purchase

[Eric Gustafson]

I would also just pull off the sheetrock on the walls, use faced batts, and then rerock.

If you go with the blown-in insulation, You can use it on the walls, too. You won't have to remove the sheetrock and you will save yourself a lot of time.

Drill holes at the top of each cavity with a HF hole saw large enough to get the blower nozzle in, fill the void, and replace the plugs you took out of the wall with a piece of backer board and a few drywalls screws. There may be a blocker board halfway up the wall. In this case, you have to drill two holes each cavity.

[Augusto Orosco]

If you go with the blown-in insulation, You can use it on the walls, too. You won't have to remove the sheetrock and you will save yourself a lot of time.

Drill holes at the top of each cavity with a HF hole saw large enough to get the blower nozzle in, fill the void, and replace the plugs you took out of the wall with a piece of backer board and a few drywalls screws. There may be a blocker board halfway up the wall. In this case, you have to drill two holes each cavity.

But wouldn't I need a vapor barrier for the walls? Or is that not needed in the garage?

[George Bregar]

But wouldn't I need a vapor barrier for the walls? Or is that not needed in the garage? Yes you need a vapr barrier. Which is why just blowing in insulation is a bad idea for walls and ceilings.

[Cliff Holmes]

http://www.google.com/products/catalog?oe=utf-8&rls=org.mozilla:en-US:official&client=firefox-a&q=infrared+thermometer&um=1&ie=UTF-8&cid=12955984420802696606&ei=NsInS9mxFISisgPavO3KDA&sa=X&oi=product_catalog_result&ct=result&resnum=2&ved=0CCcQ8wIwAQ#ps-sellers

+1 on the IR thermometer. The thing has so many uses around the house. And my wife uses it to get the griddle to the perfect temperature for pancakes!

Cliff

[Don Jarvie]

Ceiling - if your not going to use the attic for storage, etc use blown in. If you hope to use it then use the batts.

Blow in is messier but also cheaper.

[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 :eek: 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 (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 (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.

[Charles Murray Ohio]

I built my shop last year. After getting a quote, I installed it myself. A friend on my who is an air systems engineer designed the system (duct sizes and location, BTU and AC size). One of the things he recommended was to upsize the blower due to the 10’ ceilings. The system works great, better than the professionally installed one in my house. I used a 95 plus natural gas furnace, that has sealed combustion. A concentric vent brings in fresh air for the unit to burn and exhausts the gases. It took me two weeks to do both floors (the furnace is located upstairs). I also installed cold air grills that have a filter rack built in, this help keep the sawdust from being sucked through the return pipes. When it was done I saved approximately $6,000.

[Augusto Orosco]

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.


Two contractors just told me the same thing (no need for a vapor barrier since I am insulating the floor of the attic, not the roof); but at the same time I keep reading online that kraft paper faced insulation (if fiberglass) or another sort of vapor barrier (if blow in) should be used for this application. I am a little confused now :confused:

[John McClanahan]

I watched an episode of "This Old house", where they were adding insulation to an already finished attic. Tom Silva stated that any oil based primer or paint will serve as a vapor barrier. They were blowing insulation in the walls.

John

[George Bregar]

I watched an episode of "This Old house", where they were adding insulation to an already finished attic. Tom Silva stated that any oil based primer or paint will serve as a vapor barrier. They were blowing insulation in the walls.

John Again, I think there is a difference between an interior heated living space and a garage that goes unheated and has a concrete floor. What are is damper....your gargae or house? Also, there is a reason that they use an insulation WITH a vapor barrier on new construction, and don't simply prime and paint the walls. Drywall must be primed and painted...why not just skip the faced insulation and the added cost?

[Mark Beall]

From what I've heard/read current research on building methods is raising significant questions on whether vapor retarders are useful in walls/ceilings in many climates. The main issue that I've heard is that in areas where it is very cold and dry in the winter and hot and humid in the summer the vapor retarder is in the wrong place half of the time and causes problems due to that.

This page mentions this about halfway down:

http://www.ornl.gov/sci/roofs+walls/insulation/ins_05.html

mark

[John McClanahan]

Insulation with a vapor barrier is great for new construction, but Augusto listed sheetrocked, uninsulated walls. The oil based paint is an option if he chooses to blow insulation behind the existing walls.

John

[Augusto Orosco]

From what I've heard/read current research on building methods is raising significant questions on whether vapor retarders are useful in walls/ceilings in many climates. The main issue that I've heard is that in areas where it is very cold and dry in the winter and hot and humid in the summer the vapor retarder is in the wrong place half of the time and causes problems due to that.

This page mentions this about halfway down:

http://www.ornl.gov/sci/roofs+walls/insulation/ins_05.html

mark

I have been reading similar opinions, Mark, therefore my doubts. I think I will call the town and see if at least they have an official opinion on that.

[Augusto Orosco]

I would think they are 24" OC

I got into the attic tonight to double check... the joists are 32" OC. Is that standard? I guess the original builder was cheap :rolleyes:

This is probably silly question, but I have no clue: For batts/rolls, should I get the 15" wide or the 16" wide ones, assuming that I need two batts side to side to fill up one cavitiy? The exact space in between joists is 30.5". Two of the 15" sound too short, but two of the 16" would be 1.5" too wide, and am concerced about compressing the insulation and loosing R value
:confused:

[Mark Beall]

Here's another reference, although related to basements:

http://www.eere.energy.gov/buildings/building_america/pdfs/db/35017.pdf

the conclusion is similar. Trying to stop the movement of moisture rather than allowing it, can really cause problems in some cases (even if you follow what people consider to be the "correct" rules)

Based on what I've read, I suspect that, for a garage, there's really no need for a vapor barrier since:
- in the summer (assuming you don't install AC in the garage) you're not going to have much temperature differential to deal with, so it's not really an issue at all (if there isn't a temperature differential, you can't get condensation)
- in the winter (assuming you don't install a humidifier), you're not going to have much moisture in the air in the garage, regardless of the temperature. Since you're basically going to be heating outside air, your relative humidity in the garage will actually be lower than the outside air (which will have very little moisture in it anyhow).

The only real issue I can see is that you'll have to allow for the fact that any wood stored in your garage in the winter will become very dry. Make sure you leave space for expansion when you move a piece into the house.

mark

[George Bregar]

Here's another reference, although related to basements:

http://www.eere.energy.gov/buildings/building_america/pdfs/db/35017.pdf

the conclusion is similar. Trying to stop the movement of moisture rather than allowing it, can really cause problems in some cases (even if you follow what people consider to be the "correct" rules)

Based on what I've read, I suspect that, for a garage, there's really no need for a vapor barrier since:
- in the summer (assuming you don't install AC in the garage) you're not going to have much temperature differential to deal with, so it's not really an issue at all (if there isn't a temperature differential, you can't get condensation)
- in the winter (assuming you don't install a humidifier), you're not going to have much moisture in the air in the garage, regardless of the temperature. Since you're basically going to be heating outside air, your relative humidity in the garage will actually be lower than the outside air (which will have very little moisture in it anyhow).

The only real issue I can see is that you'll have to allow for the fact that any wood stored in your garage in the winter will become very dry. Make sure you leave space for expansion when you move a piece into the house.

mark Your source was about basement walls, which are a different animal. As for the rest, this idea that you won't have "much moisture" in the winter...work in your garage in th winter and watch the water form on the windows. Car exhaust is mostly water. Human exhale water vapor. The concrete slab is going to put moisture in the air. And there is moisture in it already...right now its 17F in Madison, and 67% RH.

In the summer you have high humidity, but not equal temperature. At night outside temps will cool much faster than inside because of the insulation in the walls.

And there are four seasons...the others are spring and fall. Both generally have higher humidity and cool temps.

There is a reason that insulation manufacturers and those that install it use vapor barriers. And don't tell the painting contractors "you handle it".

[Mark Beall]

Your source was about basement walls, which are a different animal. As for the rest, this idea that you won't have "much moisture" in the winter...work in your garage in th winter and watch the water form on the windows. Car exhaust is mostly water. Human exhale water vapor. The concrete slab is going to put moisture in the air. And there is moisture in it already...right now its 17F in Madison, and 67% RH.

In the summer you have high humidity, but not equal temperature. At night outside temps will cool much faster than inside because of the insulation in the walls.

And there are four seasons...the others are spring and fall. Both generally have higher humidity and cool temps.

There is a reason that insulation manufacturers and those that install it use vapor barriers. And don't tell the painting contractors "you handle it".

Yes, basements are different, that's why I said "although related to basements", however the reasons and the conclusions are similar.

If you take air at 17F and 67% RH and heat it, the relative humidity will drop very quickly. That why, in the winter, the RH in your house can be extremely low in that kind of climate. All of the sources of moisture in a house (people, cooking, showers, etc. ) are not enough to bring the RH levels up to comfortable levels (at least 30%) in most cases. Running your car in the garage to raise the humidity level could be a bad idea...

Vapor barriers are most often used currently since that has been the recommended practice. Research in the last 10 years or so is indicating that this is actually quite a bad idea in some cases. The rational was that if you have hot, moist air on one side of a wall and cool, dry (dry in the absolute sense, not in terms of RH) air on the other, that you want the vapor barrier on the hot side so that you prevent that moisture from moving through the wall, to cooler temps (which raises the RH) to the point that it gets to 100% RH and condenses. (note that these conditions generally only exist in winter and summer, there isn't enough temperature differential the rest of the year) There are several problems with this idea: You cannot stop all moisture movement, it will still happen, you will still get condensation in the walls. If you have a vapor barrier in place you then are making it harder for the walls to dry out when the conditions that caused the condensation have passed. Also in areas where it's cold in the winter and hot and humid in the summer, half of the year you have the vapor barrier on the wrong side of the wall, so it's actually making the situation worse.

If you had a new house built today, they would most likely use a vapor barrier. As the research that has been done gets incorporated into standard building practices that will most likely change in some parts of the country.

As for the situation asked about in this thread, the original rational for a vapor barrier barely exists since the RH levels in the garage will be quite low and it will only be heated part of the time. Due to both of these things, I'd be surprised if there would be any significant moisture migration into the walls.

mark

[Doug Swanson]

+1....and nobody wants to admit that vapor barriers are bad (building codes) because then you would could have a huge liability to contend with...my brother is in that line of work and it is a sticky issue to address in the codes...

[Augusto Orosco]

I spent a few minutes tonight making a couple of platforms so it's safer to move around the attic. Because the joists are 32” OC, I didn't feel that a piece of plywood would be sturdy enough to support my weight. I ended up reinforcing a couple of pieces of plywood with 2x4s and brought them up the attic space.

Moving around is going to be a challenge. The attic is not high enough to stand straight in most places, and with the joist being so apart from each other, I really need to rely on the platforms, which are not the lightest things to move around, given the reinforcement.

We'll see how it goes... I will get the insulation this weekend and will try to tackle the project at nights. I had the heater running today and brought the shop to 50F (pretty good, since the outside temp was in the low teens, and very windy), but every time I went up the ladder, I could feel how much warmer it was higher up. I think insulating the ceiling will make a big difference.

[Bill Clifton]

Ceiling - I paid $0.48 /sf for R-30 fiberglas blown in by a reputable company. It took 2 men no more than about 1 1/2 hours. Best thing I ever did was to hire it done.

Ask the same company you call for blowing in the attic about the walls. I bet they can drill holes through the sheetrock and blow it into the walls cheaply and quickly.

[Augusto Orosco]

Ceiling - I paid $0.48 /sf for R-30 fiberglas blown in by a reputable company. It took 2 men no more than about 1 1/2 hours. Best thing I ever did was to hire it done.

Ask the same company you call for blowing in the attic about the walls. I bet they can drill holes through the sheetrock and blow it into the walls cheaply and quickly.

I would like to know where all of you are getting these quotes... I decided to do it myself, because I can't get anyone to quote me less than $1,250 for 500sf. :(

Labor in Boston is very expensive!

[Ken Fitzgerald]

Augusto,

When I finished the interior of my shop, I installed the insulation dams in the eves before I put the sheetrock on the ceiling and the plywood on the walls.

IIRC it cost me just over $300 to have R-38 fiberglass blown into the 740 square foot ceiling. I checked with the local HD. I couldn't do it that cheaply.

My shop is heated with NG Lennox 75,000 btu gas furnace. I have R-19 in the walls of the shop and 1 10' insulated garage door, 3 4'x3' thermopane windows and 1 36" insulated steel walk-thru door. It isn't expensive to heat my shop. I typically set it for 58ºF. When I want to work, I go out set the thermostat for 64º and go back in for another cup of coffee. When I come out the shop is warm.

[Augusto Orosco]

IIRC it cost me just over $300 to have R-38 fiberglass blown into the 740 square foot ceiling. I checked with the local HD. I couldn't do it that cheaply.

Now you are just rubbing it in, Ken :)

I think the cheapest I can find here is an online offer at HD for 0.99sf of blown in; but only for R19. I can still do it cheaper myself with fiberglass batts and achive an R30.

[Don Jarvie]

I think HD had r30 for 10 bucks a roll.

[Chris Friesen]

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 live in the Canadian prairies. (Saskatoon, Saskatchewan) Winters are cold and _dry_. So yes, we do like to keep humidity close to 40%, but at -40 I drop the humidity to about 30% to keep too much frost from forming on the windows.

35% humidity doesn't seem unusual at all. Health Canada recommends 30-50% for interior humidity.


+1....and nobody wants to admit that vapor barriers are bad (building codes) because then you would could have a huge liability to contend with...my brother is in that line of work and it is a sticky issue to address in the codes...

Depends on where you live. Around here vapour barriers are an absolute necessity in winter otherwise the vapour in warm interior air would condense in the wall cavity. When there is a 110F temperature differential between inside and outside, you need the barrier. Summer times aren't particularly moist, so the barrier is still fine then.


As for the original question, I'd start with airtightness, then ceiling, then walls. Make sure you've got the vapour barrier boxes around your electrical outlets, or at least the gaskets under the faceplates. I had R30 fiberglass blown in to the ceiling for cheaper than buying batts at HD. The walls are R12 batts. I'd prefer more but they're only 2x4 walls.

[Augusto Orosco]

I got into the attic tonight to double check... the joists are 32" OC. Is that standard? I guess the original builder was cheap :rolleyes:

This is probably a silly question, but I have no clue: For batts/rolls, should I get the 15" wide or the 16" wide ones, assuming that I need two batts side to side to fill up one cavitiy? The exact space in between joists is 30.5". Two of the 15" sound too short, but two of the 16" would be 1.5" too wide, and am concerced about compressing the insulation and loosing R value
:confused:

This question got lost in the thread... but it has become more relevant now because I have the opportunity of buying 15" wide rolls at a large discount. Can I use two 15" wide batts side by side, or would it be too short (given the 30.5" space between joists). Would two 16" batts be too wide? What has been your experience?

[Mike Cruz]

My math says use one of each and you will be very close...;)

[Augusto Orosco]

My math says use one of each and you will be very close...;)

I know, just as close as with two 15" (but on the wider side, which might be better). I am just trying to make my life simpler and save some money: I can buy the 15" ones for about half the price per sf than the 16" ones right now.

[Mike Cruz]

I would think that two 15's, being a little shy would make your insulation efforts ineffective. Two 16's, and you have pointed out would be squeeshed in a bit too tightly. I think a 15 and a 16 would be your best bet. Of course, money comes into play. Just think of it as getting 25% off the whole job instead of 50% off by getting all 15". Hope that helps.

[Augusto Orosco]

I would think that two 15's, being a little shy would make your insulation efforts ineffective. Two 16's, and you have pointed out would be squeeshed in a bit too tightly. I think a 15 and a 16 would be your best bet. Of course, money comes into play. Just think of it as getting 25% off the whole job instead of 50% off by getting all 15". Hope that helps.

Thanks, Mike. You are probably correct. Probably better snug than loose.

Now, does insulation is measured like dimensional wood? (i.e. 16" is not really 16, but say, 15.25"?). I can't measure it directly at the store because they are all packed, and the employees look at me funny when I ask that question :rolleyes:

[Mike Cruz]

The only help I could give you there is that if you figure that normal insulation is made for studs that are 16" oc. So, that would make the space between them, what, 14.5? See what it says on the packaging and compare. Oh, and tell the folks at the Borg what you are trying to accomplish. I would imagine they would carefully open a package of each so you could measure.

[Doug Carpenter]

In the 20 years I have been a general contractor it seems the industry has changed its view on vapor barriers several times. I have worried that any job I did in the past will haunt me later. Often it is the same subcontractor that tells me what we did last time was wrong!

I think there is no need for extra vapor barrier here. If you use kraft faced insulation put it towards the heated space. If you have some sort of vapor barrier don't use faced insulation over that. I think as leaky as a garage is it isn't a concern, especially if you open the garage door often.

My insulation has a $350 minimum and doing a garage ceiling would fall under that catagory. They buy such huge quanities of material that I can't touch it by doing it my self.

I'll bet the 15" and the 16" batts are the same size. The 16'' material is made to fit between to studs or joists so they probrably measure 14 1/2".

If you are 32" oc then it will measure 30 1/2" so you might not make it. You could do it with the 16" and leave the space and then blanket another layer perpendicular to the joists but that may be out of the budget for now. If the 16" stuff you mention is actually 16 the squishing it in isn't going to cause a problem. Or maybe you could get both sizes and one of each will do the job.

For the walls later I would check with a pro because there are other options than batts and blown in.

[Augusto Orosco]

If you are 32" oc then it will measure 30 1/2" so you might not make it. ... maybe you could get both sizes and one of each will do the job.


I decided to follow Doug and Mike's suggestion and go with a 15" / 16" combination, but once I got to the store, they had a lot of 15" R30 but no 16" rolls or batts to be found :eek:. Since the 15" rolls were so cheap per sqf compared to the rest I took the risk and bought enough for the full job (they do measure exactly 15").

Late last night I was able to cover about 40% of the attic in less than two hours (not as hard as I was expecting, even with cutting around electrical boxes). Two 15" rolls side by side seem to fill the space between joists well. I'll see how it works once the job if finished. I saved a good deal of money, so I could still find a way to make make them fit tighter if needed (such as placing a roll of 15" R19 on top, right in the middle where the two R30s meet)

[Rick Metcalf]

Agusto,
If you consult your building department and indicate that you are adding heat to a space in MA, the AHJ will require you to have a building permit and meet the state energy code for the building envelope. This will be way more costly than you now imagine. The best solution would be to fill the ceiling joist space with faced batts to fit the depth of the ceiling joists. Tape the joints, joining the batts (15" to 16") and staple the kraft face to the inside of the joists close to the ceiling to seal as best as you are going to get without removing the ceiling sheetrock. Lay another layer of unfaced R-30 across the top of the joists. Make sure the soffit vents are not blocked. Pick up some owens-corning raft-r-vent shims if you have soffit style vents and gable vents. This will keep the space above the insulation ventilated and cold to prevent mold growth on the underside of your roof. If the floor is in good condition, consider sealing it with a quality epoxy sealer. With the floor sealed, other that you sweating hard over the workbench, the moisture from internal sources in a garage environment are pretty negligible. Best of luck with the project.:)

[Augusto Orosco]

Agusto,
If you consult your building department and indicate that you are adding heat to a space in MA, the AHJ will require you to have a building permit and meet the state energy code for the building envelope. This will be way more costly than you now imagine. The best solution would be to fill the ceiling joist space with faced batts to fit the depth of the ceiling joists. Tape the joints, joining the batts (15" to 16") and staple the kraft face to the inside of the joists close to the ceiling to seal as best as you are going to get without removing the ceiling sheetrock. Lay another layer of unfaced R-30 across the top of the joists. Make sure the soffit vents are not blocked. Pick up some owens-corning raft-r-vent shims if you have soffit style vents and gable vents. This will keep the space above the insulation ventilated and cold to prevent mold growth on the underside of your roof. If the floor is in good condition, consider sealing it with a quality epoxy sealer. With the floor sealed, other that you sweating hard over the workbench, the moisture from internal sources in a garage environment are pretty negligible. Best of luck with the project.:)

Hi Rick,

I spoke to the town building inspector early this week before proceeding. I explained that the garage was previously unheated, but now I have a 240v heater that I am planning to use 2-3 times a week for a few hours each time. He said that given that description, fiberglass insulation with no vapor barrier was fine (I actually mentioned that I was planning on using kraft faced batts, he said it wasn't necessary) and that I could go ahead; just make sure to leave them short enougth so the soffit vents are not blocked.

[Mark Crenshaw]

It's a 2 car attached garage with 8' ceilings and about 500sf of total area. The garage walls are sheetrocked, but with no insulation (with the exception of the wall that is shared with the house). The ceiling is also sheetrocked, but the attic on top is not insulated. The two garage doors span most of the longest wall and are already insulated with a 1.75” thick rigid foam in between the metal sheets (pre-installed by the manufacturer).

I got in on this topic late and I see you have already moved forward with fiberglass bats. But maybe my experience with my garage will help out down the road when you tackle the walls.

My garage is the same setup...one insulated, commom wall with the house. I chose to use blowin cellulose. It took my wife and I a couple of afternoons to get it done but it has made a huge difference in the temps.

Here are some pics from the project.

http://www.crenshawweb.com/texastele/ttp03.htm#insul

I built side extensions for the hopper out of OSB and when we got ready to blow the attic, we built a pen in the floor out of old plastic shelving that allowed us to break open 10 or so blocks of cellulose and just shovel it into the hopper with a snow shovel...it went very quickly and was easy to do.

The walls were a bit tougher...you have to vent the space to let air out as insulation goes in...I started with 1.5" holes...just large enough for the nozzel, but ended up opening them up to 2.5" to let the blow back exit the wall cavities. I'm going to let them settle over the winter, top them off and fill the holes next spring.

I just got a new digital weather station for Christmas so I'll be able to see what the inside/outside difference is. I can say, it's very noticable with it insullated.:D

Peace,
Mark

[Augusto Orosco]

I was able to finish the attic yesterday night. Overall, the whole project took me about 4 hours due to some areas that had additional divisions and forced me to do more cutting than expected. I ended up using about 560sf of R30 insulation.

I also used one of those spray foams (I think they are caled 'good stuff') to cover gaps I found around the door jams and around the garage door frames. I will do some additional caulking later. I also noticed that the weather stripping in one side of one of the garage doors is leaving a 1/4" gap that runs for about one foot. This happened because the garage door is a little bowed towards the inside (bumped the car against it a long time ago :o).

Yesterday was probably one of the coldest days of the season; the temperature outside was about 11F with strong wind (sub zero wind chills). My garage had gone down to 34F, which I guess says something about the partial insulation it had before. The concrete floor was also very cold. After finishing with the insulation, I fired up the heater and it raised the temp aprox. 5F. every 30 min. It got to 50F after 90 minutes. I wanted to wait and see how long before it reached 60F, but it was already past midnight, so I went to bed. I'll try again this afternoon and see how it performs. I am particularly interested on see how frequently it has to cycle to keep at 55F-60F.

I am sure the gap I found in the garage door is making things harder: I could feel the air coming from it. I have to decide how to best address that problem.

[Bryan Hosford]

I have a one car garage and have the same issue with heating. My walls and ceiling are all insulated and sheetrocked, but my floors get really cold. so I'm going to try the floating floor that was in a FW issue. Basically 2x4s, 4x8 plywood and 2x4x8 insulation sheets. looks quick and easy and should help the space heat faster.

[brian watson]

Can you post the particular issue # this was in?

[Bob Winkler]

Not sure if this is the same issue Bryan was talking about, but Issue #160 of FWW Tools&Shops had a wooden floor article. PT 2x4 sleepers with foam insulation in the bays, covered by plywood.

I am considering this also, but am worried about moisture entrapment under the foam, with eventual mold possibilities. I am now leaning towards a vented floor such as dricore or Delta-FL that has an airspace. Maybe I'm being overly anal, but I want to get it right.

Bob

[Augusto Orosco]

I was able to finish the attic yesterday night. Overall, the whole project took me about 4 hours due to some areas that had additional divisions and forced me to do more cutting than expected. I ended up using about 560sf of R30 insulation.

I also used one of those spray foams (I think they are caled 'good stuff') to cover gaps I found around the door jams and around the garage door frames. I will do some additional caulking later. I also noticed that the weather stripping in one side of one of the garage doors is leaving a 1/4" gap that runs for about one foot. This happened because the garage door is a little bowed towards the inside (bumped the car against it a long time ago :o).

Yesterday was probably one of the coldest days of the season; the temperature outside was about 11F with strong wind (sub zero wind chills). My garage had gone down to 34F, which I guess says something about the partial insulation it had before. The concrete floor was also very cold. After finishing with the insulation, I fired up the heater and it raised the temp aprox. 5F. every 30 min. It got to 50F after 90 minutes. I wanted to wait and see how long before it reached 60F, but it was already past midnight, so I went to bed. I'll try again this afternoon and see how it performs. I am particularly interested on see how frequently it has to cycle to keep at 55F-60F.

I am sure the gap I found in the garage door is making things harder: I could feel the air coming from it. I have to decide how to best address that problem.

Yesterday I fired up the heater as soon as I got home. The garage was at 40F (outside temps were on the high 20s and not nearly as windy as yesterday). I got inside for dinner and spent some time with my wife and daughter. After my daughter was in bed, I got into the garage (probably about 90 minutes had elapsed) and the garage was at a very comfy 60F . The heater was cycling probably about 50% of the time, so armed with a caulking gun I started inspecting the garage looking for drafts.

I found out that there were still some leaks around door frames, windows and the garage doors, so I started sealing those. Then I noticed that along the full length of two walls there are two pieces of wood butted together supporting the sheetrock on top of the concrete base (about 1 foot above ground level). The two pieces are not straight, so there is a small gap in between them which allows for air filtration all through the length of the two walls. The gap is not big (probably 1/4 inch at its widest), but it spans the full length of the two walls, about 40 feet :eek:!

I have a lot of stuff against the walls that needs to be moved so I can seal the gaps. It was getting late, so I called it a night and will tackle it this weekend.

The cold concrete floor certainly makes warming the garage harder, but I don't have the time or budget to install a subfloor right now. I think finish sealing all these gaps will make a difference, though!

[Bryan Hosford]

I was worried about the moisture as well, so I'm laying down 5 mil plastic under everything. And yep thanks the article in FW

[Mark Crenshaw]

As I mentioned in an earlier post to this thread, I added blow-in cellulose in my previously uninsulated garage last summer...walls and ceiling...and insulated the door with 2 sided foil roll insulation. Today was the most extreme test of it's effectiveness so far. The outside temp this morning was 8F with windchill of -3F. The temp in the garage, according to my digital weather station, was 50F. Man, that's a worthwhile expenditure! With my portable heatpump, I can get it up to a balmy 60- 65F. :)

Peace,
Mark

[Dan Burstyn]

Hi Augusto,

The ceiling is first. I insulated mine last year. It stays around 50 degrees, even when it is very cold outside.

My next problem is that the top of my garage door does not get close enought to the header to actually seal correctly and I lose a fair amount of heat that way. I can run a small electric heater for hours and not make much of a difference. So make sure that you are sealed up as well.

If you shop around, you can find insulation on your local craigslist (assuming houses are still being built in your area). Generally there is always someone that over buys, and then sells the extras for cheap.

Also, in my area there are a couple of discount/overstocked home stores.
They sell things cheaply.

Also Habitiat for Humanity has a store (where they sell stuff that they can't use on their local project that was donated to raise $ for stuff they need). I have found an ocassional item that I needed there cheap.

Also, in theory insulation will be cheaper in the spring time, as it will be out of season (maybe).

Also, while the R factor is not great, you could use the syrofoam (blue) 2" insulation as well (assuming you can get that cheap). Rremeber something in better than nothing.

Also - a Caution. The sheet rock, on the garage wall that butts up against the house, may not be generic sheetrock.

Mine, according to my local code is fire resistant grade sheet rock.
When I checked with my local zoning folks (I wanted to run additional wiring in the garage for some of my machines), I had to make sure that there were no holes in the fire sheetrock, and all holes in studs had to be filled with special fire resistant caulking, etc. The idea is to keep the garage and house "seperate" from a fire prospective.

Good luck. Also, if you can get a little here and there, put in some rafter by rafter (when you can get it cheap). You don't have to do it all in a weekend.

Good Luck,
Dan B.

[Faust M. Ruggiero]

It's probably too late for paper faced bats. The paper is a vapor barrier and must face the heated side. Your heated side is already covered with sheet rock. I believe bats with no paper are called for.
fmr