Garage Heat

So I have been kicking around for years heating my attached garage. The walls are insulated, how well I’m not sure it was already done when I bought it. The roof is not insulated, I already have to much crap up in the rafters so prefer not to do it the right way and rock it out and blow in insulation. I know a friends family years ago had a heated garage and all they did to the roof was put rolled insulation in between the 2x4s and staple some clear plastic over that. Is that going to cause ice damns? I would probably not keep it real warm in there, just enough to make it more comfortable when having a smoke and drinking beer out there. Also the garage has a chimney in it from the fireplace we do not use and it has a hole in it with a cover over it so I think I could vent it out that way? TIA

I used my garage furnace for a year or two without ceiling insulation. I just turned it on when I needed to work out there. Then I put bat in my rafters with no plastic overlay and have heated it all winter for over 20 years.
I had to saw a hole in my roof for a new chimney but your scenario sounds fine if you can seal it properly. I can only add that heated garages are one of the modern marvels up here in the winter, keeping your vehicle thawed and dry.

John Rasmussen wrote:

I would probably not keep it real warm in there, just enough to make it more comfortable when having a smoke and drinking beer out there

Trust me by the time you get to beer 5 or 6 you will have it warmed up to 70.

JEREMY wrote:

Trust me by the time you get to beer 5 or 6 you will have it warmed up to 70.

I suppose you may be correct.

Do not put plastic over the insulation. It goes beneath- between the heated area and the insulation. Putting on top will cause a nightmare

I am guessing the trusses are exposed with nothing there right now? If so, just adding poly to stop the heat from rising and escaping and the cold air coming in from the soffit will make a big difference. It is the first step anyways. Add rock and itch when you can.

Randy Wieland wrote:

Do not put plastic over the insulation. It goes beneath- between the heated area and the insulation. Putting on top will cause a nightmare

So Randy I have exposed trusses and thought of putting the batting in between the trusses and then plastic over that meaning from the floor it would be plastic then insulation then roof. Do I have it wrong?

Rodwork wrote:

I am guessing the trusses are exposed with nothing there right now? If so, just adding poly to stop the heat from rising and escaping and the cold air coming in from the soffit will make a big difference. It is the first step anyways. Add rock and itch when you can.

your gonna build up alot of condensation on the plastic if you only go with plastic only.

i would just do it right the first time and put up the ceiling, add your soffet chutes and blow it in and be done with it. you say you wont use it much but after its done you will be suprised how much time you will want to spend in the garage after its all done and you will wish you did it sooner

John Rasmussen wrote:

<div class=”d4p-bbt-quote-title”>Randy Wieland wrote:</div>
Do not put plastic over the insulation. It goes beneath- between the heated area and the insulation. Putting on top will cause a nightmare

So Randy I have exposed trusses and thought of putting the batting in between the trusses and then plastic over that meaning from the floor it would be plastic then insulation then roof. Do I have it wrong?

This is correct. But seal it good or you will have ice dams

Bearcat89 wrote:

This is correct. But seal it good or you will have ice dams

By seal it good, you mean tape the plastic down good I assume.

John Rasmussen wrote:

<div class=”d4p-bbt-quote-title”>Bearcat89 wrote:</div>
This is correct. But seal it good or you will have ice dams

By seal it good, you mean tape the plastic down good I assume.

If your not insulated above and in the soffits and heat escapes upwards it will cause ice dams if we had snow. Yes seal the perimeter and seams good

Coletrain27 wrote:

i would just do it right the first time and put up the ceiling, add your soffet chutes and blow it in and be done with it. you say you wont use it much but after its done you will be suprised how much time you will want to spend in the garage after its all done and you will wish you did it sooner

I didn’t think of the condensation. Never left it just plastic. I agree and would do it all the way, right away. Since you are putting up sheetrock you might as well add can lights, outlets, pull down cords from the ceiling, and ceiling fans. Tip: the shoots are way easier to put in before the vapor barrier or anything else is in. I hate crawling on my belly in the attic. Take your phone out of your pocket If you must crawl in your attic. Cracked the screen of 2 phones over the years crawling around.

Why do you have to belly crawl in the attic ? I can walk in mine

Bearcat89 wrote:

Why do you have to belly crawl in the attic ? I can walk in mine

To get to the very end of the truss where the shoots would go. I can walk in the middle. Not on the ends.

Rodwork wrote:

<div class=”d4p-bbt-quote-title”>Bearcat89 wrote:</div>
Why do you have to belly crawl in the attic ? I can walk in mine

To get to the very end of the truss where the shoots would go. I can walk in the middle. Not on the ends.

Lol. Makes sense.

No expert here but had mine spray foamed this year. Then you can leave the attic open

I heat a 25x30x11 garage with an electric 220v 7500 watt heater from like fleetfarm/menards. walls are insulated with R19 (2×6) and ceiling has about 10″ of blow in. At night when i’m watching tv, I hear it kick in like once every other hour for about 15 minutes. set at 40 degrees.

slough wrote:

No expert here but had mine spray foamed this year. Then you can leave the attic open

Curious how much you paid for that?

Spray foam enough for your vapor barrier, then blow in the rest.
Absolutely add soffit chutes, soffit vents and roof vents.
50/50 soffit to roof venting.

Set Stat at 62, perfect bourbon drinking temp.

Eelpoutguy wrote:

Spray foam enough for your vapor barrier, then blow in the rest.
Absolutely add soffit chutes, soffit vents and roof vents.
50/50 soffit to roof venting.
Set Stat at 62, perfect bourbon drinking temp

I know I should but trying to cut some corners if it is still safe to do so and I still keep my easy access to rafter storage then I would really like to do that.

John,
I am ex-carpenter. Here is what I suggest.

1) Put in the soffit chutes and roof vents next summer.
2) Wire as necessary for lights, fan, get the LED lights from Menards.
3) Install a drop down stairs that allows you to pull down the ladder for easy access to the garage ceiling.
4) Install Kraft faced insulation between the ceiling rafters.
5) Staple poly to the ceiling joists.
6) Rent lift and install sheet rock.

The drop down ladder and Kraft faced insulation will allow you to keep the attic storage. You can also probably add some plywood in the attic between the braces to make storage and access easier.

x2 on the pull down steps, but use something like this
https://www.energyefficientsolutions.com/attic-stair-cover.asp?item=HW-25-56

Spray foam is the only way to go to go unless you prefer ice dams.

Obviously do what you need to but standard trusses are not designed to have any load stored on them other than sheeting on roof and Sheetrock on the bottom. I have seen roofs collapse in the winter in high snow loads from people storing things on the trusses. Also as the drop down ladder is nice unless is is approved they are bad idea and your insurance company can get funny if a fire starts in your garage and it spreads to your house. Code does not allow them to be installed unless they have a burn rating. Definitely vent the cavity unless you are doing spray foam(hot roof) but spray foam is not a cheap option. If you use the craft backed insulation the paper will be the moisture barrier just make sure it faces down.

LOL –
I asked a truss designer about the bottom cord. He said “It is only engineered for drywall. I said when we set the trusses we walk on the bottom cord to set strong back, rat runs, etc.
He said (with a red face) Yeah i know.
Everything in construction is over engineered.
Costing the consumer a fortune.

Your GTG John.

FYI – you could do a “hot roof” put that really wouldn’t apply in this application.

BTW – I do need new rims and tires. call you soon.

John Rasmussen wrote:

<div class=”d4p-bbt-quote-title”>slough wrote:</div>
No expert here but had mine spray foamed this year. Then you can leave the attic open

Curious how much you paid for that?

22 x 48 garage with about 5/12 pitch was about 3500 for the roof (3-4″ thick).

Eelpoutguy wrote:

BTW – I do need new rims and tires. call you soon.

Sounds good Matt. Thanks

slough wrote:

22 x 48 garage with about 5/12 pitch was about 3500 for the roof (3-4″ thick).

Thanks. A little more than I was hoping to spend for sure. Nice size garage you have sir.

hnd wrote:

At night when i’m watching tv, I hear it kick in like once every other hour for about 15 minutes. set at 40 degrees.

Not sure this winter so far it would get down to 40 in the garage without a heater. Keep mine at 55 when im not in it and 68 when I am. Its been nice so far with the warm weater barely ever cycles.

Adding to this thread- my garage is insulated and rocked, but not taped or mudded and the sheetrock job looks like an amateur with too many beers did it. Rather than tear it all out and start over (the correct and expensive way), would there be any real downside other to covering the ceiling with those pink foam boards for some added insulation up top?

KPE wrote:

Adding to this thread- my garage is insulated and rocked, but not taped or mudded and the sheetrock job looks like an amateur with too many beers did it. Rather than tear it all out and start over (the correct and expensive way), would there be any real downside other to covering the ceiling with those pink foam boards for some added insulation up top?

Here again do what you wish but if you put foam on your ceiling and do not cover it you just created a huge fuel source if your garage caught on fire. By code the foam would have to be covered with a fire proof material.