My brother has an old house probably built in the 30s or 40s in renovated in the 50s. The very front of the house looks like it may have been a converted porch. There was recently a leak which prompted me to pull down some of the sheet rock on the ceiling. I was a little surprised to see that there is no insulation at all above that area ( which explains the heating bills ).

I’m wondering what the best way to insulate the area is. The roof is at about a 20 degree angle, do I insulate the area about the Sheetrock, or the angles of the eves? How do I make sure everything is vented correctly ?

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  • Are you OK with insulating this from above? What are ground snow loads like in your area? Dec 30, 2020 at 2:43
  • To insulate from above I would have to tear the roof off, don’t know the snow loads but it has held up for 50 years the way it was constructed
    – user379468
    Dec 30, 2020 at 4:39
  • Ignoring the ventilation issue, I would use 6" batts or rolls with a vapor barrier, installed with the vapor barrier down (towards the living space). That will give you an R-19 value with typical batt material (fiberglass, rockwool), which will reduce your heat leakage through the roof by ~95%.
    – SteveSh
    Jan 29, 2021 at 2:49

2 Answers 2


Normally the insulation is on top of the sheetrock, and venting takes place just below the roof boards, or anyway between the roof boards and the top of the insulation - unless you have a lot of space to work with, more insulation is better up until you block the venting, and then it's not.

Given that it's a "converted porch" the high side of the venting may be difficult, or at least involve getting creative, if it butts up against a wall rather than connecting to a vented attic - in which case you'll need to install vents on the top part of the roof surface. Intake vents at the eaves/soffits should be more normal.

Buildings of that age, never assume with respect to insulation - there may be other areas completely lacking it that you'd expect to be insulated.

  • It is butted against the building, and its a hipped roof making the high side even more challenging, any suggestions?
    – user379468
    Dec 30, 2020 at 1:54

Rolled insulation with a vapor (paper) face if the room is an enclosed space not open to exterior. Or if there is a living space above it.

If the room is enclosed with solid walls you should install the insulation with the paper face to the inside.

If your insulating a room above the porch install with the paper face away from the porch.

Unless the room is being conditioned (heated or cooled) there is little reason to insulate.

  • Its a single level addition that has nothing above accept roof
    – user379468
    Dec 30, 2020 at 4:37

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