Old Garage make over


Old 05-10-12, 05:54 PM
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Join Date: May 2012
Posts: 1
Old Garage make over

Hello Everyone,

I am currently working on setting my garage as small workshop. One that is set up for small detail work. In located in the Los Angeles area, so cooling is my main concern.

The garage is a 1960's era detached building, 20x20 with 1 door, 1 window, 1 garage door. It peaks at 10'6", sloping down to 7'8". It has a stucco exterior and is framed out with 2x4 for the walls (16 OC), 2x6 for the rafters (24" OC.) It does not have any roof venting or soffit vents.

My plan is to drywall the walls and ceiling. Currently, the rafters are exposed and there are only 2 joists (at the 7'8" height). I want to keep the joists AND add collar ties about 1/3 the way up to make a ceiling (at about 8'6"). This would give me room to manipulate sheets goods. The existing joists will remain and can also serve for holding light materials.

I have already started adding r13 fiberglass the walls.

Since I do not have ANY venting right now, I was considering the following and wanted to know if I am way off here...

1. Drill out 2 holes between rafters to the outside at a diameter of 2.5 and use round screen covers3. - for a total of about 36 holes (10 on each side of the garage). Cap this with a round vent cover that has 2.610si nfa (square inches of net free ventilation area)This should give me about 94 si of low venting. (I arrived at this number based on 1sqft per 300sqft - halved for the lower vent.)

2. Add a ridge vent. (high venting)

3. add vent baffles that will go from where the wall and rafters meet (and where my new vents holes will be) up slightly past the new collar ties so the insulation has an air gap for that section of the roof.

4. Add r-19 in the cavity between the rafters, the baffles, and the collar ties. This works about to be around 4'.

5. Add insulation on my new collar ties (probably r-19).

6. Drywall - patch and paint.

Does this plan seem reasonable?
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Old 05-10-12, 07:07 PM
Tolyn Ironhand's Avatar
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Join Date: Nov 2007
Location: Twin Cities, MN
Posts: 12,185
Seams to be good to me.

Being an electrician, if you haven't already, I would suggest getting your feed for a subpanel out to your shop. You might want to surface mount it for ease of adding new circuits later.

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