David Joyce | July 11, 2016

Video // Insulation & Air Sealing

Superinsulated Sunroom (1): Exterior Foam Layer


A superinsulated sunroom might sound like an oxymoronic idea, but it is not. Just use triple glazed windows and thick foam over the wall framing and roof


This room will have ‘Outie’ windows, which means that the windows will be flush to the outside of the thick wall.

They will require solid backing for the flanged windows. The two inch bucks will match the 2 inch thickness of each layer of exterior insulation.

All of the the pieces of foam will be small, so they put some thought into where the seams will land.


But before installing foam on the wall, they detail the bottom with a bug shield, which runs along the bottom and up some sides.  

Next, the seams in the wall sheathing are taped as a primary air barrier mechanism.


Now, the foam can go on the wall. On the first layer they run continuous pieces from the flashing to the top of the wall, and piece in between the uprights above and below the windows.

Corners are carefully flushed.

Each piece is held in place with a minimal number of nails because more nails will go through the wooden furring strips which will ventilate the siding. After filling the spaces between the uprights at the top and bottom of the walls, the second layer is started with a continuous rip below the windows.

This will act as the bottom of the back-out frame you’ll see in the next video.


—Thanks to David Joyce, for opening his jobsite to our film crew. Thanks to Calvin Cutts, Damien Higgins, John Albert, and Patrick Burke for doing the work and working with us at the same time.



Why not use SIP? would have been done in half the time or less.

Daniel Morrison's picture

SIPs may be a good choice for an add-on, but this house was completely wrapped in insulation (two layers over the roof and walls), so it made sense to continue with the plan on the little addition to the back.


More to come,


I cannot view this video because it does not stream well.  Audio fades in and out and the progress wheel keeps turning.  Please reduce size of file for better streaming.  Thanks.

Daniel Morrison's picture

Must be your current connection, Rita, YouTube optimizes videos for streaming.

Maybe try again when you get out of the tunnel?



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