Garage attic insulation

[5Cent]

OK, finally got time & $ to get this done this week. I've got a 22x22 attached garage that was finished when the home was built, so there is no fire wall and the attic is open above the whole house. Only access to attic is in garage.

When built, the garage section was not insulated, so it's time to do it. I have what looks to be around 2' eave around the whole home, and the styrofoam vents were used to dump the air above the now insulated portion.

Few ?'s:

1.) I'm stuck between blown and batt insulation. I want a clean look and an even cleaner enviroment in the attic area. The blown looks like it will be very dusty and I don't want it falling into the garage area when opening the attic access.

2.) Do I need a vapor barrier? The garage is sheetrocked all around and temps go from -10* to 100* here in Ohio. If needed, where should it go? The sheetrock is already finished.

3.) If I go with batt insulation, which direction should the paper go? Does it differ if vapor barrier is installed?

Thanks guys

 

[ripsnortMN]

I have a similar sized garage (20x22) and have decided to do the blow-in insulation. Mainly because it is half the price of the batting. And I think the blow-in will fill every nook and cranny. Its a bit dusty blowing it in but overall it would be a good choice in my opinion. Thats what im going with.

 

[5Cent]

I have a similar sized garage (20x22) and have decided to do the blow-in insulation. Mainly because it is half the price of the batting. And I think the blow-in will fill every nook and cranny. Its a bit dusty blowing it in but overall it would be a good choice in my opinion. Thats what im going with.

Livin in MN, what are you doing for a vapor barrier? Do you have drywall or OSB up?

 

[ripsnortMN]

Livin in MN, what are you doing for a vapor barrier? Do you have drywall or OSB up?

I am doing 6 mil plastic for a vapor barrier for the ceiling. And then 5/8" drywall for the ceiling. I will be hanging the drywall in a few weeks. So far I only have the walls insulated with r13 batting.

 

[mdoolittle]

Blow in some "pink" fiberglas insulation. Very little dust, super easy to do. Owens Corning has an Attic Cat system that is pretty slick to use. I blew in 23" for an R value of 60 in my 24 X 48 in a couple hours with my wifes help. I was going to do the batts but after checking prices I could blow in twice as much insulation for less money. It was then a no brainer.

 

[tatra]

there have been some fires that were attributed to the open attic you describe i believe..............tried to find some info on this as it was a local story here in wiinnipeg...............iirc the local building codes were changed so as to keep this from happening again and builders were more than onboard with the changes................one fire cost the lives of two fire fighters..........the reason i mention this because while you are at it, do what will be necessary to protect your investment.................if i find more info on this i will add it later............

 

[5Cent]

there have been some fires that were attributed to the open attic you describe i believe..............tried to find some info on this as it was a local story here in wiinnipeg...............iirc the local building codes were changed so as to keep this from happening again and builders were more than onboard with the changes................one fire cost the lives of two fire fighters..........the reason i mention this because while you are at it, do what will be necessary to protect your investment.................if i find more info on this i will add it later............

I appreciate it. But what was the change, adding a firewall between the garage attic and house attic? The garage was finished in 5/8" fire retardant sheetrock during the construction of the home.

 

[rburke65]

Ya, I think we need more information on these "attic' fires. I have a ranch with an attached 2 car garage,open to the house and no fires since 1970 when the house was built. How did the open attic attribute to the fires?

 

[5Cent]

I think he's just letting us know there is possiblilty of fire spreading from either or (the garage to house, or house to garage) w/o the fire wall, even though it meets code if done when built.

I have valuables, but if I can get my wife and guns out of the house, and the truck out of the garage, the rest can burn,lol. That's terrible to say, but it's all just material things that I wouldn't have to worry about anymore. Any who, this is just another great feature of this board....it's members and their willingness to help educate on potential issues like this.

mdoolittle, thanks for the info on the blown-in pink insulation. I want to find out what the minimal purchase (bail wise) is to get the machine for free.

On the vapor barrier topic. Since the ceiling sheet rock is already up, fully finshed and painted, would it be acceptable to do blown in insulation to the top of the 2x4, then put down a vapor barrier, then thin plywood on top of that for storage of small stuff (i.e. seasonal stuff like christmas wreaths etc..)? This would allow me to keep the dust contained with the vapor barrier tight overtop, then plywood over that.

 

[rburke65]

Thanks 5 cent...now I understand.

 

[5Cent]

I am doing 6 mil plastic for a vapor barrier for the ceiling. And then 5/8" drywall for the ceiling. I will be hanging the drywall in a few weeks. So far I only have the walls insulated with r13 batting.

Got to bring this back up, b/c I still don't understand where the vapor barrier has to go

The garage is already finished, just not insulated. The 5/8" sheetrock is screwed directly into the trusses, and I will be doing blown-in insulation.
Where do I put the vapor barrier if the sheetrock is already hung and finished?

1.) Line in-between trusses with plastic, then add blown-in on top, leaving it open to cooled attic space.
2.) Do blown-in directly onto sheetrock, then stretch vapor barrier over blown-in to "encapsulate" it.

Is my thinking that #2 will create a moisture trap and ruin the insulation?

 

[5Cent]

Well after reading some more, I found my answer.

The VB needs to go on the heated side, so that means I will lay that down first over the trusses and sheetrock.

Do you just lay it in, nice and snug or staple it? I'm thinking staples are adding holes which is lessoning the effectiveness of the VB.

 

[jerry j]

The V/B is not as critical as your making it out to be..

The only time a V/B is really required is if your home or garage
has an absolutley, tremendous Humidity problem..

Some causes to look for are windows with excessive moisture (water) on glass and window sills, the amount of showers taken, # of people in home,
the humidifier set too high, hanging clothes to dry in the basement, cooking (boiling water), fish aquariums, Lots of plants brought in for the winter..

Any part or all of the above adds moisture in the air..

I've seen a combination of some of the above that have caused real problems,
like black mold on the underside of the roof, tips of roofing nails, in the attic
with balls of frost on the tips, light fixtures with slight water in the globes..
Those are extreme examples, but it is happening out there..
Use some common sense and control the moisture in the home...

My home, built in 1963, 3 br. brick ranch with attached garage..Pull down
stairway in the garage.. No Vapor Barrier ----- No Problem....

Make sure that you have more than enough ventilation above the insulation,
and never, never put a V/B ON TOP OF ANY INSULATION.....

 

[5Cent]

The V/B is not as critical as your making it out to be..

The only time a V/B is really required is if your home or garage
has an absolutley, tremendous Humidity problem..

Some causes to look for are windows with excessive moisture (water) on glass and window sills, the amount of showers taken, # of people in home,
the humidifier set too high, hanging clothes to dry in the basement, cooking (boiling water), fish aquariums, Lots of plants brought in for the winter..

Any part or all of the above adds moisture in the air..

I've seen a combination of some of the above that have caused real problems,
like black mold on the underside of the roof, tips of roofing nails, in the attic
with balls of frost on the tips, light fixtures with slight water in the globes..
Those are extreme examples, but it is happening out there..
Use some common sense and control the moisture in the home...

My home, built in 1963, 3 br. brick ranch with attached garage..Pull down
stairway in the garage.. No Vapor Barrier ----- No Problem....

Make sure that you have more than enough ventilation above the insulation,
and never, never put a V/B ON TOP OF ANY INSULATION.....

Gotcha, thanks for the info.

The main source of moisture will be from the snow on the vehicles during the winter, and the ventless heater I am currently using. I do keep the door cracked to help reduce the moisture when in the garage, and plan to move to a vented heater hopefully by next winter.