How to insulate garage AFTER drywall installed?

[Musky-Hunter]

We recently purchased a builder spec house that has about 2/3 of a three car garage exterior walls rocked and finished taped but not insulated. The ceiling is also rocked and taped but not insulated. The exterior walls and ceiling do not have a moisture barrier behind the drywall. The exterior sheeting is a fiber board finished in vinyl siding. The home is located in Minneapolis where we commonly get temps 20f below for several days. The drywall was installed horizontally on 12" walls. I am considering to tear off the middle board and try to slide batts behind the top and bottom boards without tearing off. Another option would be to DIY blow in but I have no experience with it and fear settling. If it will take as long to fill the holes as it would for me to tear off the middle boards and replace, I would go with batts. Either way does not provide any moisture barrier which I am concerned about only because I don't know if it is acceptable to cut this corner or not.

Any suggestions are appreciated.

Thanks in advance.

 

[blkhonda1991]

blown cellulose would be the easiest method although its not really a diy type job and it doesnt settle that much these days, its far from what it was years ago.

 

[GSSFC]

blown cellulose would be the easiest method although its not really a diy type job and it doesnt settle that much these days, its far from what it was years ago.

It is def. a DIY job. Most of the big home improvement stores will rent you the machine at little to no cost if you buy the material from them. You simply find the center of the stud bays, drill the appropriate hole, insert the tube and fill until the machine labors. patch the hole and move on, I do it professionally but the concept is the same. It is easiest to do from the outside generally especially if you have vinyl siding.

Tim

 

[dreamingmuscle]

It is def. a DIY job. Most of the big home improvement stores will rent you the machine at little to no cost if you buy the material from them. You simply find the center of the stud bays, drill the appropriate hole, insert the tube and fill until the machine labors. patch the hole and move on, I do it professionally but the concept is the same. It is easiest to do from the outside generally especially if you have vinyl siding.

Tim

Agreed DIY job Biggest headache is if they put in fire blocks in the walls. Easy fix though. Just drop a tape measure or a weight down the wall if it hits bottom at 8ft fill it up. If not drill another hole 1.5" below where your marker stopped and fill that cavity up too.

Glen
________
ipad guide

 

[BooUrns!]

You're confusing DIY blown-in cellulose which is intended for loose fill in attics with wall-bar cellulose applications. The wall-bar cellulose is not as easy to install as loose fill and you may end up with cold spots where the insulation did not reach.

Despite these issues, it is the least invasive and cost effective method. Spray foam is much more expenive and IMO not worth the gain in R value for the price tag.

 

[dreamingmuscle]

Oh and if you are worried about settling. Cover the holes behind the siding with thin guage calvanized steel sheets and screws. Come back a year later and top it off and patch the hole right.

Glen
________
Honda RC163

 

[Kevin54]

I would pull the siding off (simple job), pull the fiberboard off, insulate, then reassemble. It will be a lot faster and cleaner than blown in insulation. But instead of fiberboard, replace that with some OSB for strength.

 

[blkhonda1991]

It is def. a DIY job. Most of the big home improvement stores will rent you the machine at little to no cost if you buy the material from them. You simply find the center of the stud bays, drill the appropriate hole, insert the tube and fill until the machine labors. patch the hole and move on, I do it professionally but the concept is the same. It is easiest to do from the outside generally especially if you have vinyl siding.

Tim

i have heard, and i may be confusing this with the spray foam, that it winds up being more expensive for just materials than it would be to hire it out

 

[sharpshooter]

Do you know how to hang/tape/finish dry wall? If you do I would think about pulling the rock down from the walls, then going in there with roll insulation and then blow the attic...

 

[tatra]

guys unless i've missed domething, he mentions no vapor barriers, so unless he removes the drywall and applies one , he's just throwing his money away, no?................the only alternative i believe is spray foam but i/m not awrare of what kind you would use for enclosed cavity fill.............

 

[GSSFC]

guys unless i've missed domething, he mentions no vapor barriers, so unless he removes the drywall and applies one , he's just throwing his money away, no?................the only alternative i believe is spray foam but i/m not awrare of what kind you would use for enclosed cavity fill.............

There are no foams that would be usable that would also act as a vapor barrier. Only open cell foam is conducive to retro fit cavity fills and the you cannot get enough in a wall cavity to negate the a vapor barrier. If the garage is heated you need a vapor barrier insulation or not. Retro work is done all the time and you have to weigh the benefits and the consequences. I would not spend the money to rip off the drywall and install closed cell foam or open cell foam for that matter, in walls, you won't gain a whole lot over cellulose. I would use a residential blower and use cellulose and enjoy the benefits of an insulated garage without a big mess. Cellulose in the walls as a blind fill is not messy. Blown cellulose in the attic or open walls is a huge mess. I do it all except filterglass and can answer any question you have.



Tim

 

[GSSFC]

i have heard, and i may be confusing this with the spray foam, that it winds up being more expensive for just materials than it would be to hire it out

Yes DIY spray foam costs more for materials alone than labor and materials for a pro to do it. And you get a better product too. DIY cellulose is cheaper for sure and very easy to do, hardly any learning curve and you can usually get the machine for free when you buy the material from a home center.

Tim

 

[Musky-Hunter]

Thanks for the replies. I had not thought about tearing off the vinyl but I must admit, replacing drywall is far more preferable to me as a DIY project than trying to remove and re-install the vinyl that we have that is no longer available in the color we have. I also forgot to mention, on of the walls on the house side has Hardy board.

One thing that is not clear to me is why I need a vapor barrier in an un-heated garage. There will certainly be a temperature difference to the outside even without a heater but I expect it will not be more than 20f at the extreme ends of our -15f winter and 100f summer. If I attempt the DIY blow in celluose method I will not have any moisture barrier. Is that ok or will I get mold or more settling in the insulation than normal?

I noticed nobody commented on the idea of stripping off only the middle of three horizontal wall boards and attempting to insert batts behind the top and bottom boards still attached to the wall. Any comments on this approach? I don't know how feasible it is to get the batts in place tight to the ends of the stud cavity without compressing the batt too much. This approach will also not provide any moisure barrier but I'm uncertain if this is important.

Thanks again.

 

[vc-onthepc]

maybe no one thinks its a good idea to strip off center sheet and install batts of insulation.. maybe because all the nails from the siding will be poking through causing many obstructions and even more headaches ... not to mention wiring and such

if your happy withthe siding outside leave it pull the drywall its not difficult to finish nor is it expensive . my 2 cent's

 

[vc-onthepc]

try chris angel maybe he could help ? sorry i couldnt resisit its late and i have the tv on

 

[BigChevy80]

I pulled the drywall down in my garage and installed R-13 batts and 6 mil vapor barrier. Then I covered it back up with 1/2" OSB.

I hate drywall in a garage!

 

[Brad54]

Not an expert, nor have I done much insulating. However, from what you've written, I'd say you can certainly DIY the blow-in insulation in the attic above the garage. That's a pretty easy one. If you don't have access up there (no trap door?), cut in a trap door. Even if it's short and has a lot of trusses, with some plywood on top of the rafters, you can use it to store some stuff.

You said 2/3 of the garage walls are finished. Sheetrock is pretty cheap. If you're going to be spending a lot of time out there and will be heating it, I'd pull down the existing drywall and start over.

Remember too, it's a garage--a cold spot or two isn't going to be that big of a deal. You want it warm enough to work, not warm enough to walk across it in your jammies in the middle of the night.

-Brad

 

[larry4406]

I pulled the drywall down in my garage and installed R-13 batts and 6 mil vapor barrier. Then I covered it back up with 1/2" OSB.

I hate drywall in a garage!

Be carefull with this - you may have just lost your fire rating between the garage and house (assuming the garage is attached/integral to the house).

 

[PAToyota]

Be carefull with this - you may have just lost your fire rating between the garage and house (assuming the garage is attached/integral to the house).

X2! 5/8" fire-rated drywall all the way!

 

[Jim Dawson]

Be carefull with this - you may have just lost your fire rating between the garage and house (assuming the garage is attached/integral to the house).

I just added a second attched garage with OSB on the walls and was only required to have fire rated drywall on the common wall with the house. Actually the common wall is stone, but I had to use fire rated drywall on the gable where it joined the house.

 

[StingRay]

As far as the vapor barrier part goes alot of paints on a finished wall will provide more than adequate vapor barrier. There are also vapor barrier paints available. All that would be required after that would be to gasket the switches and outlets.