Insulation facing question

[crazybrit]

I have an garage with an uninsulated attic.

Ceiling of garage is 5/8 drywall.

Retractable ladder privudes access to attic above.

In the attic the floor is 2x6 joists covered in plywood. Some of the bays have R19 but the install is a mix of paper down and paper up.

I'm going to insulate the remaining bays but what is the correct orientation for the vapor barrier? Normally the paper faces the warm side. For inside spaces that would normally be down next to drywall but this upper attic space gets really hot in summer.

The 2x4 eaves under roof of attic are not insulated. Attic us used for storage only

Thanks

 

[Mick56]

The paper should face down. Is the plywood in the attic attached? I would remove the plywood and flip the insulation so it all faces down.

 

[crazybrit]

Thanks for the reply. I'll flip it all so paper is facing down.

The plywood is loose. Screwing the plywood down was something I was thinking of doing after I finished adding the missing insulation.

 

[kelpaso1]

Wont matter much which way you put it. Paper is not much of a vapor barrier. But ya paper side down.

 

[crazybrit]

Followup question. As I said, the floor of the attic is 2x6 and that is where the partial insulation is. Drywall on underside (ceiling of garage). Plywood on upperside.

Is there any value in adding R13 to the 2x4 bays of the actual roof rafters?

The attic space (200 sq ft or so) is just used for storage. I added a temperature operated fan a couple of years ago to try and keep temperatures up there reasonable in the summer. I think it kicks in at 85F (as I said, it gets hot up there).

 

[rburke65]

I believe you want the floor insulated, OR the attic roof rafters....NOT both. I’m sure the insulation experts will be here soon.

 

[CraigStu]

I agree w/ kelpaso1. If it will take more than 20 min to flip it, I'd wouldn't bother. I will be interested to see what others think re; insulating the roof rafters. Thinking back to houses we have owned, they all had the attic floor only insulated. But I am trying to figure out if the heat is outside, how could having 2 layers of insulation not be better than one layer.

 

[manwithtools]

Ceiling only in your case. Insulation between rafters can cause condensation issues with roof decking. Also, that insulation would not help in any measurable way unless the whole attic was insulated.

 

[NUTTSGT]

Paper down, or towards the interior/conditioned space.

No I would not do the underside of the roof.