GARAGE INSULATION / FINISHING (GYM)

[CherryHatchetWoodworks]

Hey all,

Hoping to get some help, this particular garage has me scratching my head.
Just bought a house, and want to insulate and drywall etc the semi attached garage to make it a bit more comfortable during the long winter months.

Won’t be heated continuously, but off/on with a space heater most likely around workout times.
There are a few weird characteristics though, and I’d like to keep as much headroom as possible 

Location: Outside Hamilton, Ontario, Canada.
Garage shares rear wall & part of ceiling (already closed off) with main house.
2x4 stud walls, 24” OC
2x4 rafters/trusses same spacing.
Don’t want to close in the ceiling, try to maintain as much headroom as possible.

Complications :

Soffit vents only run along one side of the garage, and then at the very front portion of the angled peak. 
I don’t see any ridge vents or other vents above the garage.

**
Obviously going to try to seal any air gaps, holes etc around the garage door etc.

I was thinking I would add 2x2 to the 2X4, walls so I could use R22 Roxul on the side walls as it will be a deeper cavity 

For the ceiling (almost like a cathedral style, not a flat ceiling) - I’m kinda stuck.

I’m not sure if I should leave an air gap for the soffit vents,(2x2 nailed underneath sheathing, rigid foam to those) as I don’t see a roof vent or ridge vent, or if I should treat it like an invented roof with insulation directly underneath the roof sheathing. You can def see the nails from the shingles coming through the sheathing as well, not sure if that complicates things further, but I know that would lead to heat loss conduction as well.

Any suggestions on this problem? I’ve talked myself in and out of solutions for a while now and any help would be appreciated.


Photos attached for reference.
(PS: I KNOWN THAT INSULATION DOENS’T INHERENTLY WARM A SPACE, BUT KEEPS HEAT IN LONGER.. HOWEVER I’LL DO ANYTHING TO AVOID  THE BARBELL STICKING TO MY SKIN AGAIN NEXT WINTER…..)

 

[RussellS]

Just my thoughts and ideas.  NO expertise.  It would be very easy to vent the left side soffit with a small drill bit.  An hour of drilling and it would be vented.  As your garage is now, venting is not really needed since there is no heating or air conditioning.  No way to build up any moisture due to temperature differences with the outside since your garage is pretty much the same temperature, atmosphere as the outside.

I'd recommend insulating and sealing up the side walls.  Rockwool, fiberglass, styrofoam, whatever you want to use for insulation.  Seal with drywall or plywood.  Run electrical lines for outlets before sealing.  Put a ceiling in the garage.  Drywall or plywood.  Put insulation on top of the ceiling but still leave a gap with the plywood roof.  Couple inches?  I don't think you need roof ridge vents because you have enough air movement with the soffits holes.  Roof vent would be nice, yes.  But since this garage will only occasionally be heated, any moisture difference that builds up when its heated won't be enough to really matter.  All the soffit venting will work good enough to circulate outside air underneath the roof plywood and keep it from being at a different climate that develops moisture.  And of course seal everything you can between the inside finished space of the garage and the outside.  You don't want to see any light or air from outside when you are inside.

 

[CherryHatchetWoodworks]

Thanks for the reply.  I'm attempting to do this by "closing up" and insulating the rafter cavities, but not create a horizontal ceiling... I'm trying to leave the cross-trusses open so that there is a bit more headroom, room for my pullup bars / rings, etc. I know this complicates things, but I'd like to do it if I can.

I'll certainly think about creating vents on the left side -- can't believe I didn't think of that!

Thanks again.

Just my thoughts and ideas.  NO expertise.  It would be very easy to vent the left side soffit with a small drill bit.  An hour of drilling and it would be vented.  As your garage is now, venting is not really needed since there is no heating or air conditioning.  No way to build up any moisture due to temperature differences with the outside since your garage is pretty much the same temperature, atmosphere as the outside.

I'd recommend insulating and sealing up the side walls.  Rockwool, fiberglass, styrofoam, whatever you want to use for insulation.  Seal with drywall or plywood.  Run electrical lines for outlets before sealing.  Put a ceiling in the garage.  Drywall or plywood.  Put insulation on top of the ceiling but still leave a gap with the plywood roof.  Couple inches?  I don't think you need roof ridge vents because you have enough air movement with the soffits holes.  Roof vent would be nice, yes.  But since this garage will only occasionally be heated, any moisture difference that builds up when its heated won't be enough to really matter.  All the soffit venting will work good enough to circulate outside air underneath the roof plywood and keep it from being at a different climate that develops moisture.  And of course seal everything you can between the inside finished space of the garage and the outside.  You don't want to see any light or air from outside when you are inside.

 

[TSO_Products]

[member=68946]CherryHatchetWoodworks[/member] - smart to ask before you remodel. 25 years in Minnesota have taught me a thing or two about what to do next time.

Heat, consider infrared.
A space heater in your climate in combination with an unsuitably built structure will likely leave you disappointed.

I would pay a lot of attention to ventilation, moisture inside the structure and what heating might do to cause ice dams outside with water damage following while you're not watching.

A commercial residential professional building inspector is a great resource and you may find it wiser to pay for a little consulting first rather than discovering you unintentionally created some problems for yourself at least when you go to sell the house.

Hans

 

[Cheese]

I did something similar to an upstairs attic turned into a loft master bedroom. It was all 2x4 construction and I screwed & glued (construction adhesive) 2x2's to the existing structure. That gave me 5" deep joist/stud/rafter pockets. I then used 1" thick Celotex Thermax foam board with foil facers and I maintained a 3/4" space between the foil side of the insulation and the bottom of the roofing surface. That gave me an adequate run for ventilation that ended in a ridge vent at the top.

I located some plastic standoffs that were attached to the 2x4's that maintained the 3/4" ventilation space. The Celotex was cut to provide a tight friction fit and this "sealed out any air movement". I also caulked each Celotex panel in-place just to make sure everything was sealed up.

I then filled the remaining cavity space with Owens Corning fiberglass insulation.

1" thick Celotex combined with a 3/4" space = R10
3 1/2" Owens Corning fiberglass insulation  = R15
After 15 years of Minnesota winters I'm very satisfied with the results.

[attachimg=1]

 

[CherryHatchetWoodworks]

Thank you so much. This was my idea as well, however, I don’t think I have a ridge vent in the garage, so I worry about condensation or air having no where to go once it’s entered the soffit vents.... even with the air gap and XPS/Rigid Foam.

I REALLY appreciate the help and advice!

JB

I did something similar to an upstairs attic turned into a loft master bedroom. It was all 2x4 construction and I screwed & glued (construction adhesive) 2x2's to the existing structure. That gave me 5" deep joist/stud/rafter pockets. I then used 1" thick Celotex Thermax foam board with foil facers and I maintained a 3/4" space between the foil side of the insulation and the bottom of the roofing surface. That gave me an adequate run for ventilation that ended in a ridge vent at the top.

I located some plastic standoffs that were attached to the 2x4's that maintained the 3/4" ventilation space. The Celotex was cut to provide a tight friction fit and this "sealed out any air movement". I also caulked each Celotex panel in-place just to make sure everything was sealed up.

I then filled the remaining cavity space with Owens Corning fiberglass insulation.

1" thick Celotex combined with a 3/4" space = R10
3 1/2" Owens Corning fiberglass insulation  = R15
After 15 years of Minnesota winters I'm very satisfied with the results.

[attachimg=1]

 

[Cheese]

Thank you so much. This was my idea as well, however, I don’t think I have a ridge vent in the garage, so I worry about condensation or air having no where to go once it’s entered the soffit vents.... even with the air gap and XPS/Rigid Foam.

I REALLY appreciate the help and advice!

I didn't have a ridge vent either. [scared]  Just grab a beater circular saw with a new disposable blade and go up on the roof. Remove the cap shingles, lay down a pair of chalk lines and start cutting.  [smile]  Just follow the instructions that are packaged with whatever ridge vent you decide to use.

I installed a Cobra ridge vent that was designed for snowy areas. 

FWIW...a friend and I installed a "regular" Cobra ridge vent on his 50' long out-building. Unfortunately, after a driving snowfall, the second floor of the building would have a thin layer of snow about 18" wide on the floor, right down the center.  [sad] [sad]

 

[huntdupl]

Cathedral ceiling will certainly complicate things.
If you're going for a cathedral, its advisable to provide a continuous baffle to a ridge vent. There are off-the-shelf versions or you can site build them with XPS foam board being sure to seal all the edges. These range from 1-2" air gap - 1-2" strips on either side of rafter against sheathing, foam board between rafter bays.

You did mention trusses, but the biggest challenge is often meeting code for R-value in the existing rafter depth. Spraying the underside of the baffles (around trusses) isn't going to be aesthetically pleasing. I would scrap that and use a flat painted gyp ceiling as your air barrier. Batt insulation in the ceiling.

USGBC and GBA are great resources and have a pretty active forum for construction means and methods. Here are a couple links:
https://www.buildingscience.com/documents/published-articles/pa-crash-course-in-roof-venting/viewhttp://www.schluebarchitecture.com/resources/CathedralCeilingConstruction_GBAnov2011.pdfhttps://www.greenbuildingadvisor.com/article/lstibureks-rules-for-venting-roofs

 

[sancho57]

Full fill spray foam and a split unit for heating

 

[Packard]

Closed cell is supposed to be even better than open cell. 

I spent a week in an igloo we made while camping.  With no heat source other than our bodies, we maintained a temperature of close to 40 degrees (four occupants).  It was ranging from -20 degrees F. to +2 degrees F. 

So a well insulated room can be relatively toasty. 

Building out 2" x 4" walls to 2" x 6" will significantly increase the insulation if you use 6" batts. 

 

[ChuckM]

I have had excellent results from using the Reflectix, this kind:https://www.homedepot.ca/product/reflectix-48-inch-x-25-ft-double-reflective-insulation/1000167795

It's light weight, avoiding any potential stress on the garage door motor.

Foil installed in Jan. 2021 - a cold snap arrived in early Feb.:

- Outside -31C for close to a week
- Shop warmed on one of the days to about 10C - 15C in the day while working there for about several hours
- The next-day temp in the shop: 0C.

In the recent heat wave (+30C or so), the shop remained very comfortable with the door closed.

It's hard to find a simpler or cheaper garage door insulation solution.

 

[Nardo]

I used 2 inch thick 4'x8' sheets of foam from Lowes.  Screwed them down with screws and large fender washers to hold.  taped the seams and used two layers.    Used canned foam at the edges along with Siga tape.

Spray foam will also be a good choice but that comes with $$$ and some issues with the roof decking.  Go with a good applicator and you will be fine.

You have to either finish the space or block the soffit and ridge vents - leaving them will the insulation worthless.

 

[Sparktrician]

Suggest that you take a good look at Roxul insulation, whether it comes in boards or batts.  It doesn't collapse and it's also good as a sound deadener.  It's also great for fire resistance.

 

[Packard]

Only because no one else has mentioned it, you will probably want to use something for insulation for the flooring. 

My recommendation is horse stall mats.  They are a full 3/4" thick and much denser than the floor mats for just walking on.  They have interlocking patterned edges.
https://www.greatmats.com/horse-sta...MIqsD50qqs9AIVCmyGCh0r6QWREAAYAiAAEgL8ePD_BwE

A 4' x 6' mat is $86.00.  It assembles fast.  Your feet will thank you. 

 

[RobS888]

I can't help much with the insulation, my one car garage is cinder blocks and mostly below ground. Even has a cement ceiling. I bought these garage door hinges with springs to force the door against the frame. The amount of light that I could see around the door went way down. The hinge wheel things were about $120 for a single door, called green hinge or something. They do make it harder to raise the door though.
I saw recently that you can buy roller channels that have slight bends in them to force the door closer to the frame. 

I have a dehumidifier that runs the condensate outside, so it can run continuously. It actually keeps the garage around 60 degrees on its own.