How best to insulate the roof/attic space of a Cape Cod?
Thank you for your article on radiant barriers. I hope you can help me. I
have a (hot in the summer, cold in the winter 2nd floor) approximately 1,300
(about 650 per floor) sq ft Cape Cod on Long Island, built in 1956 w/2 x 4 16" oc construction. I have already re-insulated w/R-13, vapor barrier fiberglass and added new drywall to the 1st floor. The 2nd floor has 2 bedrooms separated by the stairs in the center of the house. The 2nd floor
has an attic or crawl space, behind the knee walls, and though recently
insulated with R 19, is quite drafty due to the non sheathing and board built
exterior walls wrapped in tar paper. I am dormering the back of the 2nd floor
to add space (bedroom and bath). My contractor has said he will eliminate the
ridge vent and build a roll roof. As you know and as I have read, the later
will invite wind driven rain/snow into the attic. I will purchase a gable fan
to help eliminate heat in the summer. I was going to have a radiant barrier
to help keep the 2nd floor cooler during the summers as it gets quite warm up
there, (partly due to the old/original insulation), but after reading your article I’ll no longer
be doing that. I will also add a vented sky light at the top of the 2nd floor stairs to help exhaust summer heat and cooking heat/odors (humidity?) as the heat goes up the stairs to the 2nd
floor, as the stairs acts like a chimney.
My question is how to best insulate the 2nd floor? My contractor will be
wrapping the entire house w/Tyvek (over the existing asbestos? shingles - is this a good idea?)
and adhering to it ¾ inch DuPont “blue board” under vinyl siding. I am
leaning towards blowing in insulation in the walls and adding between the
roof rafters, rafter vents, to run from the 1st floor exterior
overhang vents to the ridge. Should I also add insulation around/underneath these
vents? I want to exhaust heat through the gables, hoping
to help keep the roof cooler and 2nd fl warmer in winter. Also, though the 2nd floor is finished (1960), I’m ripping out the existing drywall and old insulation so I can blow in
new insulation into the walls. What’s your opinion on how best to proceed?
Posted Oct 24, 2011 9:41 AM ET
Edited Oct 24, 2011 10:38 AM ET
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