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what to do after insulating perimeter garage walls

Holbs

New member
Joined
Jan 29, 2012
Messages
3
After spending a good 8 hours this weekend reading 50+ pages of 'heating and a/c', i believe i know what needs to be done, but with some questions.

some stats and info:
1.) i have a medical condition (claustrophobia ). I had to remove the drywall ceiling in the garage if i ever planned to do weekend warrior auto mechanic and woodworking (havent read anything about this in the forums) :)
2.) my garage. a 2car attached garage. 24'x18'. drywall finished walls, not insulated. 24' OC trusses, no insulation. concrete slab. 9' high from floor to trusses. stone tiling on roof, stucco for exterior wall. Northern Nevada area with little humidity, 100degree summer and 20degree winter nights, little rain, little snow, 4,000 feet above sea level (near lake tahoe).

From what i have gathered with the info in this forum, insulation is key to a efficient comfortable work area for woodworking & auto work. So, my first step will be to use up my $500 lowe's gift card and blow in fiber insulation in the 3 perimeter walls and insulate the garage door itself with those styrofoam blocks i read about here. i'll also be adding exterior garage door wind dams along the outside seams.
Here is my questioning issue. I have soffits every 6feet along perimeter. However, i see no ridge vent. Only some passive 2'x4' vent, about 2feet from roof apex. It's as if the roofing OSB directly connects to the center 2x4 (pictures are below). I would "assume" there should be a gap so airflow can freely escape out if there was a ridge vent. My trusses are 24" OC. I'll be either doing R19 (i believe R19 is acceptable) 24" rolled faced pink panther batts, or unfaced pink panther with 8mil plastic (i have to investigate the cost of either). As i read... a vapor barrier is a must or at least a 'do it and play it safe' way to go. And ensuring no blockage of soffits and the use of those airflow cavity styrofoam or plastic between trusses (do i just need 1 where the soffit is... or a good 8 or 9 from soffit to supposed ridge vent, per truss?).

After insulating the walls and garage door, I assume the next step is to insulate up in the ceiling. Without a ridge vent, i'm concerned about airflow, mildew, ice dams, etc. But then, maybe the building code for the zone i live in didnt require it.

I am currently just a weekend warrior and amateur at the woodworking and aok in auto mechanics. So will not be going at it full time. I'll eventually seal the floor, add a 52" ceiling fan (i'm dutch so i like fast spinning things), paint the walls, and add a used REZNOR forced gas heater ($250 locally on craigslist), add more electrical outlets, and add 3 T8 lighting fixtures i have laying around.

i'll add pictures below.
picture 1: the soffit opening every 6 feet along perimeter.
picture 2: my kayak stored up there. i think, a 1.5" yellow gas line, and electrical cables that feed into the house.
picture 3: with no ridge vent, i assume this is the only way air can escape above. this is the passive vent near the roof apex where a ridge vent should be, i believe.

-eric
 

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buzz4041

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Joined
Sep 13, 2011
Messages
730
Location
South Texas
Quick question first. Is your soffit construction made in such a way that the air can pass between the spaced vents you have in it or are they only air ducts at each individual vent. This will determine if you need soffit vent baffles in all the spaces or just at the soffit vents. My experiance is the more soffit intake the better. (Note I have continuous soffit vent so all are open.)
Do not cover up any entrances of air from the soffit to the attic. You do not need a ridge vent as those passive roof vents will work as intended. (not as good as a ridge vent but will work). If you keep the soffit clear then you should have no problems with mildew, ice dams, etc as the passive vents and soffit entrance will work as designed. When it comes to insulation time it all depends on what product you choose. Initial layer should have a vapor barrier is my understanding and that is how I did mine. Good luck.
 
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nwav8tor

Well-known member
Joined
Feb 21, 2012
Messages
239
Location
Spokane, WA
From what I guess, your intent is not to install a finished interior ceiling so you can have as much open space as possible. You just want to insulate the roof deck for heat retention, is that correct? This can be done, but in that case I don't believe you want ventilation at all. The roof vent and soffit vents you have are used for air circulation in an unheated attic space ABOVE the ceiling and insulation.

If you did use roll or batt insulation right under the roof, you'd need to ventilate each truss space. That would require a ridge vent and vents at the lower end of each truss space and continous runs of vent baffle chutes from the lower vent openings to the ridge vents in EACH truss space so all the lower roof surface could be washed with air. All that is NOT very practical.

I think your best bet for insulating the roof deck would be rigid foam sheets or spray foam. There are specific products, procedures and requirements for this type of approach. Talk with a contractor or re-post you question under a different title such as "Options for Roof Deck Insulation."

Paul
 
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