Insulation Questions

[Pete Staehling]

I am moving to Tallahassee and setting up shop in a two car garage.  Since January average daily lows are in the upper 30's and August average daily highs are in the 90's, I figure insulation is in order.  The walls already have sheet rock so I am thinking of blowing in fiberglass into the walls while I have the machine there to blow fiberglass into the ceiling.  The rest of the ceiling is already fiberglass.

 

I am planning to use Styrofoam panels on the garage door.

 

Am I on the right track here or should I be doing something different, like using batting in the ceiling, taking down the drywall to insulate, or something else?

 

All of this is based on the assumption that the walls are not already insulated.  Probably a good assumption, but I am not sure.

[dwacker]

Has technology changed enough over the years to keep the insulation from settling in the lower part of the wall? We had our house done 30 years ago and when we gutted the downstairs down to the studs the walls where half full.

[RichardA]

Cut a piece of drywall from stud to stud, see if there's insulation in there before you make any commitment.  Foam on the doors is good....Make sure there's a good seal on the door bottom.

[Coop]

Take a 1/4" bit you don't want and drill a hole in the wall. If you can't get the bit out, you've got insulation!

[Guest]

I don't know what is normal in Florida but if your garage is sheet rocked I'd be surprised if they aren't already insulated.   

[Pete Staehling]

I don't know what is normal in Florida but if your garage is sheet rocked I'd be surprised if they aren't already insulated.   

 

 I hope you are correct.  It would be nice.  My realtor seemed to think that it was pretty likely for them to not be insulated, but I guess I will find out after settlement (the 27th).

[Tom Cancelleri]

Do you have electrical you want in the walls already? If not, I'd do that first and then insulate, and kill 2 birds with 1 stone.

[Guest]

You did not ask about heat/AC, but it is all related.  Shade, insulation, venting, and exposures all dictate your building temperature, so some of it you will figure out when you get there and live there a while.  My garage is decently insulated and "partially" attached, I have 2 outside walls and 2 walls that are half attached to the house and half outside.   I don't need any AC in the summer and it does spend a lot time over 90 here in august.  I just added heat, but if it never got below 30 outside I would have been fine.  

 

When it is 30 outside, it is about 50 in my garage.  I added heat for the below 0 days when it was 10-20 inside my garage.   With my insulation I would have been find in a 30-90 outside temperate range.  My house was built in 1982 

[Pete Staehling]

When it is 30 outside, it is about 50 in my garage.  I added heat for the below 0 days when it was 10-20 inside my garage.   With my insulation I would have been find in a 30-90 outside temperate range.  My house was built in 1982 

 

That is encouraging.  It won't be 30 or below much of the time and when it is it is only an overnight low.  It does get into the low 90s a lot though and humidity is often very high.  The garage door is in the morning sun and there is a wall with a window on the south side so I expect some solar heat gain.

 

I plan to insulate and then wait and see how it is before resorting to heating and cooling.  I was told that the central AC is somewhat over-sized for the house so I probably could add a register in the shop if the heat becomes unbearable, but I am tolerant of a pretty wide range of temperatures so I hope to not need too.

[Raefco]

In the damp climate and wide temp swings, if the walls are not insulated, I would check into spray foam, no moisture barrier needed, no condensation because the air cannot permeate  the foam and it is a good sound barrier. I have been told they are spraying it inside walls the same as they are blowing in cellulose, through bored holes that are later plugged. 

 

I had my whole house spray foamed, the only draw back to date is the ventilating the house, we are planning on adding an external fresh intake on the secondary heating and cooling system.

[rodger.]

I have done a lot of research on this, as I have the same dilemma.  I was originally going to go with blown in cellulose, but decided it was not what I wanted.  I looked into foam, but the price is over the top, and it still requires demo or addind onto the existing drywall (small space for me).  I am tearing down the drywall and adding roxall (mineral wool) and a VB (6mm).

 

My ceiling is done (room above) with foam.  There are issues with adding traditional insulation and plastic vapour barrier in a garage ceiling if the space is not consistently heated (moisture build up).  So look into it before you do the ceiling (some insulaton guys can do a better job with the details than me).  I called two separate professional companies about blown in cellulkose, and one said "you absolutley need a vapour barrier in the wall, so blown in wont do" (even though he knew I couldnt hire him then) and another told me the exact opposite!   Frustrating.  Do a search on the forum, I asked similar questions about 6 months ago and got some good replies.

[Pete Staehling]

Just thought I would mention some additional thoughts that I had.  In Tallahassee the temperature is typically reasonably nice at some portion of any 24 hour period.  In the Summer that would be in the wee hours of the morning.  I was thinking that an exhaust fan could be set with a timer and an inside and outside thermostat.  A vent or an intake fan to let outside air in would probably be needed as well.  It could be set so that at some predetermined time it would run for an hour if the inside and outside temperature meet some predetermined parameters.  So it would run for an hour only if the temperature warranted it.  There could also be a winter mode that warmed it up in the afternoon if it was too cool inside and warmer outside.  I think that in my case the summer mode would be more important.

 

It may not be necessary or effective, but if I find I need it I will probably try it before adding heat or A/C.

 

I grew up before A/C was common in residences and we manually did something like that in our house with a big fan in the attic and an open attic hatch.  It worked very well.  Once the air cooled off outside the fan would cool the house in minutes.