How To Add Insulation To The Outside Of A Roof

George and his team insulates a roof from the outside in with two pound closed cell polyurethane foam in a residential attic.

How to add insulation to the outside of a roof.

At that point what you are doing is building a r e m o t e wall read more about that here. Because old roofs were often framed with 2x6s there isn t much room for insulation. You have an un vented roof. Installing insulation that acts as a vapour barrier on the outside will not serve you well except if you add enough of it to the point where about 2 3rds of the total insulation is on the outside.

Or ripping off the existing metal roof and adding the insulation on the roof deck. At that point what you are doing is building a r e m o t e wall read more about that here. If adding insulation to the outside roof is prohibitively expensive then the alternative is to add it to the inside. At any rate the problem is creating your air and thermal barrier at the existing metal roof plane.

If you decide to add rigid foam insulation to the ceiling inside you ll have to nearly fill the rafter bays to get a layer of sufficient thickness. Adding to the outside is more reliable. 4 strap with 2x4s and then i was considering cross strapping with 1x4s to help create better cross ventilation as on the back of the roof there are skylights and then the front has two valleys see attached pic. This video shows you how to use knauf insulation rock mineral wool rmw for sarking insulation installed above rafters and covered with homeseal lds weather.

That s much more common these days than it used to be but not accepted by everyone. Tear out the sheetrock fur out the joists and add our insulation there and re sheetrock. Another few inches isn t really going to do it. The insulation this article recommends is a vapor barrior which would prevent the vapor from migrating out of the house.

It would probably be easier to insulate from the inside and add false architectural elements if you have the headroom of course. Installing insulation that acts as a vapour barrier on the outside will not serve you well except if you add enough of it to the point where about 2 3rds of the total insulation is on the outside. 3 add r31 of foam to roof to create the correct inside to outside ratio of insulation as currently there are faced r30 fiberglass batts on the interior of the rafter bays.