I need to get started on insulating and finishing the interior of my garage. The outside sheathing is 5/8 OSB. That seems overkill for the interior.

I did partially finish the insulation but did not install plastic between the OSB and insulation. If I should change that, now is the time.

Is going to be a workshop for wood, electronics and light mechanics for the mowing equipment. I do not require beauty.

Do I want OSB, plywood, drywall or some sort of paneling? Cheap is good but what's right?

Really, all you need is 1/2" dry wall.

OSB burns very well, I would not use that. Personally I would use 5/8" firerock (commercial rated drywall). I might screw on some 1/2" plywood over the drywall in the lower 4 feet.

I would paint the plywood bottom edge, and install it with sealant on the bottom. This is to keep water from being wicked up into the drywall. You may have a water leak or spilled water at some point. On the plastic over the outside of the insulation, definitely install that.

Personally I would install more electrical boxes throughout the garage, including one for 240 volt. You might do some welding in the future, and 240 volt power is usually needed. I would run the MC cable or Romex through the studs so the receptacles are flush with the drywall/plywood. Compressed air lines would probably be run on the surface of the walls.

OSB or plywood can make it easy to hang things without hunting for studs. I installed drywall years ago and regret it as it's easy to damage and harder to hang tools on.

Now's the time to think about shelving, electrical, heating, and air filtration options. Do you have 220 outlets available already? Are the electrical outlets adequate and in the right locations? How's the lighting? All of that's harder to adjust once the walls are insulated and sealed.

Last summer I converted one wall of my garage to use french cleats to hang many tools. Lots of options.

Drywall is cheap. 1/2" is standard.

What about plastic sheet over the studs as a complete vapor barrier then 1/2 OSB (primed and painted white) for the interior finish?

It would be less expensive than finished drywall (I believe) and you can attach hangers, shelf brackets, etc., anywhere.

quote:

Originally posted by bryan11:
OSB or plywood can make it easy to hang things without hunting for studs. I installed drywall years ago and regret it as it's easy to damage and harder to hang tools on.

Now's the time to think about shelving, electrical, heating, and air filtration options. Do you have 220 outlets available already? Are the electrical outlets adequate and in the right locations? How's the lighting? All of that's harder to adjust once the walls are insulated and sealed.

Last summer I converted one wall of my garage to use french cleats to hang many tools. Lots of options.

Yeah, this is why I'm asking. Besides, I hate installing drywall. .

I was planning on mounting with french cleats so I can see everything and if something is out of place.

Except for the wall along the house everything else is paneled with pegboard. Supper convenient.

Question: Do you want/need any of your garage walls to be shear walls?

If so, then go with either 3/4" plywood or OSB.

Question: Do you want/need to have a fire wall?

If so, then use minimum one layer 5/8" sheet rock (two would be better, with staggered seams). If it's a shear wall, then apply the sheet rock on top of the plywood.

Question: Do you care not at all whether the wall has enhanced shear capacity or fire rating?

If so, then use either cheap paneling (like the 3/16" fake wood paneling, or peg-board paneling that you can find in any big box store) or 1/2" sheet rock.

I don't think a shear wall is necessary and i don't need a fire wall as the garage isn't attached to the house.

I do have to install a bunch of outlets and lights. That will be done first.

The pegboard sounds like a nice idea for surrounding the wrench.

Compare prices of OSB vs. plywood. If they’re close go with the plywood. I would use the plywood, even if it cost a bit more. Use screws to attach, measured layout of screws, then if you ever want access beneath it is an easy task to remove a sheet. Along those same lines, leave a 1/8” gap between all sheets. Results - strongest wall of those suggested, can hand anything anywhere on the wall. Reversible any time.

Why leave 1/8" gap?

quote:

Originally posted by mark123:
I don't think a shear wall is necessary and i don't need a fire wall as the garage isn't attached to the house.

I do have to install a bunch of outlets and lights. That will be done first.

The pegboard sounds like a nice idea for surrounding the wrench.

OK, since the garage isn't attached #1 check you insurance policy for the "separate structure" coverage and make sure it is enough. It is by default just 10% of your main dwelling coverage and that won't cut it for a detached garage.

#2, since it is detached, firewall isn't as important (since it won't catch your home on fire), though I can tell you as a claims adjuster, drywall absolutely works and saves the framing 9 times out of ten. All wood, forget it, that sucker is gonna burn and be a structural total loss.

What about installing FRP on the bottom 4 feet over the drywall or osb? This way you can hose down the floor without worrying about getting the walls wet.

quote:

OK, since the garage isn't attached #1 check you insurance policy for the "separate structure" coverage and make sure it is enough. It is by default just 10% of your main dwelling coverage and that won't cut it for a detached garage.

If he's using the garage for part/all of his business his homeowners won't cover it at all. I just learned that this last year with a building I have on my property.

If I keep my stuff in there, it's automatically covered. If I put any of my business stuff in there it's not covered at all and my business would need to take out a separate policy to insure it.

A few random thoughts on electrical stuff since I ended up completely rewiring my garage back when copper wire was cheap.

Outlets along the wall four feet high every four feet horizontally seemed excessive but are very handy. If possible, make it so any two outlets next to each other are on separate circuits.

Add outside outlets anywhere that might be handy before insulating and finishing.

220V can be handy for an air compressor and some table saws. Some pick a location for the air compressor, add a hose reel, and then cover it for sound insulation.

Some mount dust collection on a wall and run hoses to the device, others move the dust collector to the device. Some dust collectors exhaust directly to the outside of the garage.

Depending on ceiling height, some outlets on the ceiling near the center of the garage can be nice.

One more thought: Have to considered epoxy floor paint or other floor coverings? Now might be the time for that as well.

Only air barrier (like tyvek) should be on on the outside. Vapor barrier only goes on the inside, behind the wallboard of choice. And don't use plastic sheeting either place. The purpose of a vapor barrier is to control or limit the flow of moisture not to completely trap it, that causes problems. The air barrier on the outside is to stop air infiltration and should pass moisture to allow moisture to escape rather then trap it in the wall. Just use an insulation with the vapor barrier made on it between the studs.

Cords tend to pull out of mid height receptacles due to the weight of the cord if hanging to the floor. Absolutely, put lots above bench height, but also add some down low as well. The recitals in my garage are all waist high. I have to tie the cords up with a wire or bungee to keep them plugged in.

quote:

Originally posted by a1abdj:

quote:

OK, since the garage isn't attached #1 check you insurance policy for the "separate structure" coverage and make sure it is enough. It is by default just 10% of your main dwelling coverage and that won't cut it for a detached garage.

If he's using the garage for part/all of his business his homeowners won't cover it at all. I just learned that this last year with a building I have on my property.

If I keep my stuff in there, it's automatically covered. If I put any of my business stuff in there it's not covered at all and my business would need to take out a separate policy to insure it.

Very true and the business can be part-time and not profitable, still would be a denial of the claim.

The main home itself is covered no matter what business stuff is in it (there will be a low limit on the business property), but separate structures used for business (again, fully or only partly) aren't covered.

quote:

Originally posted by cparktd:
Only air barrier (like tyvek) should be on on the outside. Vapor barrier only goes on the inside, behind the wallboard of choice. And don't use plastic sheeting either place. The purpose of a vapor barrier is to control or limit the flow of moisture not to completely trap it, that causes problems. The air barrier on the outside is to stop air infiltration and should pass moisture to allow moisture to escape rather then trap it in the wall. Just use an insulation with the vapor barrier made on it between the studs.

You are confusing some things.

The purpose of a vapor barrier on the outside, and an air barrier on the inside, is to allow condensation to escape, if and when it occurs inside the insulation plane. With proper air sealing and adequate insulation for a given climate, condensation will not occur inside the insulation.

The primary driver of flow of moisture in a building assembly, is actually human respiration, then cooking and bath/shower usage. In really, really tight homes, the concern isn't movement of moisture through a wall assembly, but at the same time, you don't want to build in a way to trap moisture should it occur.

Plastic sheeting can be used as an air barrier, as long as it isn't doubling up another air barrier, in an assembly where the dew point could produce moisture inside the assembly.

The reasons for things like roof venting, and other long standard building practices, are tied in with the longstanding technology and available insulation.

Today, you start with your current climate, look at the difference to a desired interior temp, and figure on how much insulation will it take to separate the two such that the inside of the wall is a neutral zone.

Whereas, in the past, condensation was going to occur somewhere, because the hot and cold were going to meet somewhere in the assembly.

quote:

Originally posted by mark123:
Why leave 1/8" gap?

Because plywood expands/contracts as its moisture content changes and its temperature changes.

There's a pretty good explanation here: LINK