Insulation question

[jpz]

Hello all,

Just moved into a new house in August. Our previous house was a townhouse, with a 1.5 car garage. The living room was above the garage, and there was living spaces on both sides of the garage.

The new house has a 2 car garage, that is attached but has nothing next to either wall, or above. So needless to say it's crazy hot in the summer, and proving to be very cold this winter. There is no insulation in the ceiling or walls (they wanted way too much, and honestly I had no idea how bad the temp would be).

I am currently looking into blowing in insulation, but I have a few questions that I'm hoping you guys with experience can help with. Do I blow in insulation in just the ceiling? Or walls as well? How much of a difference will this make once it's all said and done? What R rating am I shooting for?

I'm also looking to install two 24" fans (one in each corner blowing towards the garage doors). I'm hoping that will move the hot air out in the summer.

Please fire away with suggestions. I'm totally new at this, and hoping to do it right the first time...or second time technically.

Thanks.

 

[77Mini]

You will only use blown in insulation in the ceiling, the rest will be batts. I think the standard for a house ceiling is somewhere around R50 but you probably don't need to go quite that far in the garage. Wall r value depends on the framing size

 

[Corsair4360]

The ceiling R value recommendation depends upon where you are located. For northern Utah were we live, they recommend R50 to R60. Here is a link to the DOE recommendations, http://energy.gov/energysaver/tips-insulation We are in zone 6. More insulation will make it warmer in the winter and cooler in the summer.

 

[77Mini]

If you are going to do blown in in the attic you may aswell do lots. I only have R14 in my garage ceiling but thats because I have a floor ans storage above.

 

[jpz]

I'm in PA (about 1 hour outside of Philadelphia). Looks like I'm zone 5. I will have to blow in the insulation for walls as well as the drywall is already done. Knowing how hot/cold the garage has been I wish I would have spent the money initially when the house was being built. Live and learn, I guess.

 

[Dragfluid]

I'm in PA (about 1 hour outside of Philadelphia). Looks like I'm zone 5. I will have to blow in the insulation for walls as well as the drywall is already done. Knowing how hot/cold the garage has been I wish I would have spent the money initially when the house was being built. Live and learn, I guess.

Blowing cellulose into the walls will be better than batts, anyway. Dense packed cellulose stops air infiltration, and is cheaper than glass for the same R value.

 

[Cyberbear]

I know how cold it gets where you live, my mother was born and raised there. Personally, I'd put in as much insulation as I could afford considering the hot and cold seasons there.

 

[MScott]

I'm in PA (about 1 hour outside of Philadelphia). Looks like I'm zone 5. I will have to blow in the insulation for walls as well as the drywall is already done. Knowing how hot/cold the garage has been I wish I would have spent the money initially when the house was being built. Live and learn, I guess.

If you would put that location in your profile (click on User CP in the top bar) people would not have to look up this posting to find it and the advice you receive will be much more appropriate to your climate.

 

[sands35]

I'm in PA (about 1 hour outside of Philadelphia). Looks like I'm zone 5. I will have to blow in the insulation for walls as well as the drywall is already done. Knowing how hot/cold the garage has been I wish I would have spent the money initially when the house was being built. Live and learn, I guess.

The info on insulation level is good for a house - which is typically assumed to be kept at around 68*F. R-50-60 makes sense for that when the outside is ~10*F. But a garage (at least mine) is kept at 40*F when not working (5-6 days a week) and then to 55*F when I'm in there.

For a ~30*F delta T when I'm working in there doesn't need as much insulation as a ~60*F delta T for a house.

For me it was a 10 year payback to put in an extra R-30 in the garage. Just didn't make sense. Maybe I'll do it someday.

But the end decision is your inspector. Mine didn't bat an eye with R-30 in the garage attic for a detached.

Cellulose is great stuff. The only caveat is that it will **** up water if there is a roof leak. Fiberglass will pass the water through and you'll see it sooner. Regardless, a homeowner should do a visual attic inspection at least once a year and more often if the roof is nearing end of life.

 

[DC73]

Before you go to the trouble of blowing insulation into the walls, consider this: Most of your heat loss and heat gain will be through the ceiling and via air leaks.

One approach would be to blow insulation into the ceiling based on recommendations for your climate zone. Then, air seal all penetrations and places for air to leak into walls and the ceiling including around electrical boxes, plumbing penetrations, baseboards, etc. Before you put the insulation into the attic, you can air seal where wires and plumbing penetrate the top plates of the walls.

You might find that with enough ceiling insulation and air sealing that the garage will be comfortable enough to avoid doing the walls. If not, you can always come back and do the walls later.

DC

 

[Voi]

I'm in PA (about 1 hour outside of Philadelphia). Looks like I'm zone 5. I will have to blow in the insulation for walls as well as the drywall is already done. Knowing how hot/cold the garage has been I wish I would have spent the money initially when the house was being built. Live and learn, I guess.

Are the overhead doors (or door) insulated? Do they have southern or western exposure?

Two of my doors were a DIY insulation job done by a previous owner. I had a section fall out one summer and the amount of heat that radiated through the one panel was noticeable until I got that section fixed. And I have very little direct exposure on that door.

I would look into air sealing yourself and then get bids for dense pack cellulose in walls and either dry cellulose or blown fiberglass in attic.

 

[jpz]

If you would put that location in your profile (click on User CP in the top bar) people would not have to look up this posting to find it and the advice you receive will be much more appropriate to your climate.

Will do. Thanks for the tip.

 

[jpz]

Before you go to the trouble of blowing insulation into the walls, consider this: Most of your heat loss and heat gain will be through the ceiling and via air leaks.

One approach would be to blow insulation into the ceiling based on recommendations for your climate zone. Then, air seal all penetrations and places for air to leak into walls and the ceiling including around electrical boxes, plumbing penetrations, baseboards, etc. Before you put the insulation into the attic, you can air seal where wires and plumbing penetrate the top plates of the walls.

You might find that with enough ceiling insulation and air sealing that the garage will be comfortable enough to avoid doing the walls. If not, you can always come back and do the walls later.

DC

Thanks. I was thinking about this as an option as well. I think this is the route I'll go. Since I'll be doing the work myself, there's not a big extra cost if I go back and do the walls next year after I see how well doing just the ceiling works.

 

[jpz]

Are the overhead doors (or door) insulated? Do they have southern or western exposure?

Two of my doors were a DIY insulation job done by a previous owner. I had a section fall out one summer and the amount of heat that radiated through the one panel was noticeable until I got that section fixed. And I have very little direct exposure on that door.

I would look into air sealing yourself and then get bids for dense pack cellulose in walls and either dry cellulose or blown fiberglass in attic.

The garage doors are not insulated (yet). I was planning on doing the doors at the end as they are pretty easy to do. I've done them in my past garage. The doors face East, so they get the direct sun in the morning, and then nothing beyond the afternoon.

 

[K'ledgeBldr]

If the result you're trying to achieve is to reduce the radiant heat that builds up inside the garage- adding blown-in insulation to the attic is your best DIY solution.

Radiant barrier decking would have been an excellent choice- during the construction phase.

As for the wintertime, the insulation that will be in the attic will serve no really purpose unless you're heating the garage. And of course that's short-lived when the garage door is opened.

As was previously mentioned, most heat loss AND heat gain will be through the ceiling. So insulating the walls would have a very long ROI. Also, "blowing" insulation into finished walls is beyond a nightmare. It requires several holes per cavity. Air moves the insulation, but the air has to have someway of escaping the cavity. Hence, several holes, screen or netting, lots of patience, and expect a large waste factor.

 

[RustnGrease]

I'm going through a similar situation, but inside the house, barely any insulation. I had thought about just blowing insulation in, but there's nothing to hold it there if we decide to redo the ceiling in any of the rooms. just something to keep in mind.

 

[JOHN 86GT]

As for the wintertime, the insulation that will be in the attic will serve no really purpose unless you're heating the garage. And of course that's short-lived when the garage door is opened.
.

The attached garages around here (Wisconsin ) that have insulated ceilings and walls that are un heated are at least 10-15 degrees warmer in the winter and liquids usually do not freeze . I'm not sure if this has something to do with heat loss from the heated house to the garage ?

I have not insulated my ceiling yet and my garage temp is almost the same temp as outside .

 

[DC73]

As for the wintertime, the insulation that will be in the attic will serve no really purpose unless you're heating the garage. And of course that's short-lived when the garage door is opened.

The attached garages around here (Wisconsin ) that have insulated ceilings and walls that are un heated are at least 10-15 degrees warmer in the winter and liquids usually do not freeze . I'm not sure if this has something to do with heat loss from the heated house to the garage ?

I'm sure there is some heat loss from the house into the garage but the thermal mass inside the garage is a bigger factor.

I've always insulated the ceilings of my garages. Yes, you lose a little heat when the door is open but as long as you don't leave it open for extended periods, it's really inconsequential. The thermal mass of the concrete floors, drywall etc makes it hard to lose much heat just from opening and then closing the overhead door. And if you park inside, the heat from the car engine does a nice job of helping to warm up the space.

Around here, with the ceiling insulated, we never have to worry about anything freezing in the garage even if it is unheated.

DC

 

[NUTTSGT]

I'm sure there is some heat loss from the house into the garage but the thermal mass inside the garage is a bigger factor.

I've always insulated the ceilings of my garages. Yes, you lose a little heat when the door is open but as long as you don't leave it open for extended periods, it's really inconsequential. The thermal mass of the concrete floors, drywall etc makes it hard to lose much heat just from opening and then closing the overhead door. And if you park inside, the heat from the car engine does a nice job of helping to warm up the space.

Around here, with the ceiling insulated, we never have to worry about anything freezing in the garage even if it is unheated.

DC

I'd tend to agree also.

One other thing about having the attached garage insulated is that when you go outside via the garage rather than a back door to the outside, the air coming into the house will be warmer. It can be like using an air lock similar to what is used at a commercial business entrance. I'd also rather have one side of the house having the windbreak of a garage and warmer temps of that shared hose/garage wall.

 

[NUTTSGT]

After my above post I went out took a picture of the thermometer on the back porch.... 20°F.



Then I took the same thermometer and let it sit in the garage, maybe 10-15 minutes. ... 38°F.


The house garage has R13 in the walls with 7/16" OSB covering them. The ceiling is also R13 covered with ribbed metal siding. I also have insulated garage doors, maybe an R7 or R8, I forget. Since I am not heating this garage (except when it gets very cold for days, I might grab the space heater and run it for 30-45 mins once a day) I only used R13.

No vehicles have been in or out today, neither started up nor has O/H doors opened up, just me going in and out the man door. While the thermometer may not be a high dollar unit, it is the same one used for both pictures. It was not heated or breathed on in any way to produce a higher temp.

 

[jpz]

Thanks for all the tips guys. I'm going to go with blowing in the ceiling. It seems like that will provide me with the best immediate return. I will more than likely skip the walls, as the garage is currently averaging about 10-15 degrees above the outside temperature.