Garage drywall question

Hello,

I am having a detached garage built and one of its walls will require fire-rated drywall and corresponding Rockwool-type insulation (this is because this side of the garage is less than 5-feet from neighbor's property line).

I intend to drywall and insulate the remainder of the garage's walls and its ceiling too. Will use fire-rated drywall and standard faced insulation for this portion of the garage. I intend to have a 4000 BTU electric heater in the garage to heat it in the winter months (live in lower portion of Michigan and will only heat the garage when I am going to perform work in it).

My question is, because the Rockwool fire-rated insulation is not faced, should I use some type of vapor barrier over it before installing the interior drywall.

Local building code requires that exterior side of garage stud must have fire-rated drywall over it too, but in my opinion I don't think it would be necessary to put vapor barrier over this side of Rockwool Insulation.

Thank you.

 

Vapor barrier should only be on the heated side of the wall.

 

On a detached garage that is only heated part time, I dont think you need to worry about a vapor barrier. But you are kind of at the mercy of your building inspector. So if you want to make sure I would make a call to their office and ask if it is required. If it was a house, and heated fulltime, it would likely need one. A garage... IMO its doubtful.

 

"I intend to have a 4000 BTU electric heater in the garage..."

I don't think your heater will have a snowballs chance especially in a large space with only one wall insulated. You haven't said the size of your garage but a 50'000 btu jet engine style heater often seems under sized in an uninsulated two car garage.

 

I think the entire garage will be insulated.

 

OK, this is something new, why the hell would it matter that a wall is within 5' of a property line so that it now requires insulation! Fire protection to a neighbors house I can maybe understand, to a property line?

 

Not really sure why the wall requires insulation, beyond the fact that it will be fire retardant type such as Rockwool. Only reason I can think of is that it adds another layer of fire protection.

 

Sure, but to what!

You do this between your attached garage and your house but to a property line?

 

Garage is 16' x 22' and will be fully insulated.

 

Such is life in the great state of Michigan. I don't see the sense in it, but I got no choice.