Protocol for insulating/Dry walling attic space

Re: Protocol for insulating/Dry walling attic spac

Dave Bair

Spray-on insulation is the answer to the odd-spaced rafters. I believe it also is a vapor barrier. It's pretty pricey, though.

The purpose of the baffles is to allow air-flow through the attic via vented soffits and roof vents. However, you do not appear to have vented soffits and therefore, do not need baffles. If so, you can insulate right onto the roof sheathing, provided you install a vapor barrier between the drywall and the insulation.

Re: Protocol for insulating/Dry walling attic spac

Dick Coers

Would you consider rigid foam nailed to the bottom of the rafters? You loose some space, but eliminate the odd cutting, and chutes. You could rip sheets of thicker foam to insert between the rafters, keep them away from the roof skip sheeting, then add another 1" rigid on the bottom of the rafters. Not sure if foil back with foil tape on the seams works as a vapor barrier or not.

Cold roof

Mike L

as mentioned spary foam the bottom of the plywood and sheet rock over the top. It is a bit pricy but well worth it in sound deaden and insulation value. It will repay for it self in a few years.

Re: Protocol for insulating/Dry walling attic spac

Barry Irby

Go to YouTube and Check out "Building Science Insights: To Vent or Not to Vent" by Joe Lstiburek. I haven't watched it lately but have taken several classes form Dr. Joe. He is sometimes dense and hard to grasp, but I think he is the best building scientist in

the country.

Call your local Building Official (under an assumed name) and discuss it with them.

Call local insulators and spray foam companies and talk to them.

It depends on what part of the country you are in. Predominately cold or hot or mixed.

Might also call the tech department of your roofing manufacturer.

The tar adhesive sticking the fiberglass to the paper facing of your insulation is a vapor barrier, but yours is pretty ragged. Hard to imagine it is reliable.

Re: Protocol for insulating/Dry walling attic spac

Pete in Holland MI

You're in snow country. To prevent roof damage, you need to keep the underside of the roof the same temperature as the outside to keep the snow from melting, causing icicles & ice dams. This generally means venting the eaves & ridge to create air flow and to keep any inside heat from heating the roof deck.

Packing the rafter cavities with fiberglass doesn't allow for this air flow under the roof deck. Spraying enough foam will prevent nearly any heat from escaping. Parking slabs of foam in the cavities will be like super-insulating your house and the kids leaving the doors open. The insulation needs to create a sealed shell to really work.

This Old House magazine had an interesting idea in an article that I thought had merit. In the rafter cavities, install 1x2 strips in the upper corners. Attach sheets of 3/4" foil faced foam to these sheets. Insulate the underside with your insulation of choice. Make sure to create a path of air flow from the eave end of the foam panels to the ridge. This system caused a separate barrier between the roof deck air flow, and the insulation within the house. Thought it was a pretty cool idea overall.

Good luck !

Re: Protocol for insulating/Dry walling attic spac

Philip F Duffy

May I suggest you look into what kind of glass is in that big window. A single pane thickness will be a real sinkhole for the heat to escape. - -just my 2cents P

Re: Protocol for insulating/Dry walling attic spac

Don Stephan

Here in Cincinnati it seems that ice dams occur at the gutter, so it may not be an issue if the building does not have gutters. Not sure if shingles reportedly will last longer if there is continuous venting on underside of the roof deck.

Re: never read that but what I did!

Larry Clinton At Frankfort, (Central) Indiana

When I built my 30' X 30' shop about 15 years ago, I used truss construction for the roof.

Trusses were custom designed so that I ended up with a 10+ wide X about 8' tall room in the center of the upstairs 30' long with knee walls.

I installed vented eaves, and installed 1" X 1" boards against the roof sheeting and the corner of each truss, sealing the opening from the boards to the walls. I then installed foam board tight against the 1" boards sealed clear up to the roof (roof ridge vent).

Then we installed the walls to encapsulate the room, blowing the area behind the knee walls full of insulation.

In the area above the room I installed 2" thick foam board them thin plywood. Even though I don't work in the shop regularly at this time I keep it heated in the winter and air conditioned in the summer to prevent rust

on the tools.

It is interesting to watch the roof when the cold weather hits and the sun is out as the ridge sometimes has several birds and sometimes even squirrels setting on it!