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No soffits. Air sealing and insulating attic. Should I spray foam eaves, or…

patricknorton | Posted in Green Building Techniques on

Howdy All,
I have a brick house located in Climate Zone 4. Saint Louis. Built in 1948, the attic was insulated at some point, but was never air sealed. To make it easier to update the wiring and air seal the attic floor, the old insulation has been removed. 

Now comes the fun part: the house has gable vents. It has no edge venting. There are no soffits to vent, there is no overhang. The rafters end at the edge of the brick, capped by a fascia board wrapped in aluminum. Some tiny amount of air gets in through some gaps between the fascia and roof sheeting, but the gaps are mostly useful for wasps. 

I could use something like Air Vent’s The Edge Vent to vent the roof edge: 

http://www.airvent.com/products/intake-vents/the-edge-vent

That said, I’d prefer to completely seal the attic: air seal the attic floor, spray closed cell foam from the fascia board till it’s 16-20 inches in height inside (I’d like R60 in blown insulation up there). I believe I’d also (need to) cap the gable vents. 

Am I on the right track here, or should I hack and claw my way to a vented roof structure w/ considerably less insulation on the outside edges of the structure? 

Thanks for any advice!

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Replies

  1. user-2310254 | | #1

    Patrick,

    Another option would be to use flash and batt to insulate the roof line. (See https://www.greenbuildingadvisor.com/article/flash-and-batt-insulation.) You would use less foam and probably save a bit on cost.

    1. patricknorton | | #2

      Thanks for the heads up, Steve!

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