Garage insulatiion options

Will1987

What would be recommended as the cheapest and easiest and most economic insulation for a garage? Its a fairly ordinary garage and I'm turning it into a woodshop and will have a space heater of some kind in there. The walls are concrete block and the ceiling is just an ordinary gable roof with asphalt shingles. I was thinking of just putting reflective foam board type insulation on the block walls. But could I also put that between the rafter s? Or would I go with R 19 fiberglass? Why is fiberglass generally used between rafters? seems to me reflective insulation would be easier to put up quickly, wouldnt be subject to sagging and falling down as much, and could even be taped with insulating tape where it meets the rafters.
also any suggestions for the door and side door? its got an automatic raisong door and a side door with a lot of airflow around it.

Thanks,
Will

concretemasonry

For the walls, I would put (glue and nail) 2x2s at 24" O.C. with 1 1/2" extruded polystyrene between. Cover with drywall, plywood or OSB.

If the garage is attached, you will need 5/8" drywall to get the required fire resistance for the common wall.

Truss or framed roof? If truss, I would blow in cellulose. Fiberglass is just not as effective and can lose insulation with moisture and dust. In any event make sure you have ventilation (soffit and ridge) to prevent overheating and extend the roofing life.

oldfrt

I like the reflective foam board idea.Easy to install,not too expensive,and light weight.
My heating contractor had the 2inch reflective board in his shop,and it stayed real toasty in there.
Some considerations;
It may have to be covered to meet building code
It damages easily,should be protected anyways
So this may be an added expense.
When installing fiberglass insulation between the rafters ,you have to allow air flow over the top of the insulation.(Gable end vents and ridge vent)

The foam board is highly flammable,so give this some serious consideration.

All in all,for the cheapest out,consider just doing the roof first.If the block isn't cracked,leave it for now.Cement has a way of absorbing heat and releasing it back into the room after the heat is turned off.Most of the heat travels upward anyways.

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Will1987

Yeah I'm trying to keep this as cheap as possible. But did you mean by "I like the reflective foam board" idea that you like it for the ceiling also?

oldfrt

You could use it on the ceiling.It will depend on the amount of time you'll spend in your shop.and if your in an area with long cold winters?
Ideally,I think the R19 would hold the heat in for a longer period,cutting down on fuel costs.If you get the faced insulation,and staple it up real good it should stay up.
What size are the rafters?There should be an air space above the insulation which allows accumilated moisture to escape.
Look at this site:
http://www.ornl.gov/sci/roofs+walls/...on/ins_01.html