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Nathan Rose
Posted on Friday, December 17, 2004 - 08:46 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Moderator/Admin Only) Ban Poster IP (Moderator/Admin only)

I noticed when I moved into my house (60+ year old slate roof) that the decking on the north side was somewhat blackened. However, as there were no signs of current moisture, I didn't worry.

However, tonight I discovered extensive condensation all over that side of the roof (and on the windows, but not on the south side, which also shows no blackening).

There is old fiberglass insulation under the attic floor. Replacing or upgrading it does not seem very practical, since the attic floor is tongue-in-groove, and in any case there would be no way to put in a continuous moisture barrier on the warm side without taking down the ceiling plaster on the second floor.

There are gable end windows in the attic, which in the summer I open and fit with louver inserts. I don't know how much ventilation they would provide if I kept them open all winter; and we have enough trouble heating the house already without letting more heat escape from the attic on purpose.

Should I insulate along the roof line? There are no soffits or ridge vent. Is there some better solution?

And in the meantime, what can I do to minimize the problem?

Thanks for any suggestions.

Nathan Rose
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Walter Musson
Posted on Saturday, December 18, 2004 - 09:27 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Moderator/Admin Only) Ban Poster IP (Moderator/Admin only)

You could have blown in fiberglass insulation installed which would require just holes drilled thru the attic boards.
Some paints can act as a vapor barrier for the ceilings below this newly insulated space,and then venting will be necessary.
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admin
Posted on Sunday, December 19, 2004 - 01:22 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Moderator/Admin Only) Ban Poster IP (Moderator/Admin only)

Warm air from the interior is escaping into the attic space and condensing on the underside of the roof sheathing. You can probably eliminate this by ventilating the attic space (i.e. opening the windows in the attic during the winter). Otherwise, you will have to stop all air infiltration into the attic from the heated living space.

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