insulating under a metal roof installed over skip-sheathing
drorabaugh
| Posted in Energy, Heating & Insulation on
my condition is a brick structure with a skip-sheathed roof covered with metal roofing. there appears to be remnants of a layer of paper under the metal. the roof is uninsulated. In the winter (as in NOW!) a fair amount of ice forms on the underside of the metal roof. how would I best treat this? my inclination is to install faced insulation into the rafters. there is no ridge venting. floor is blown in cellulose.
Replies
Moisture condensing on the underside of a roof, most of the time, indicates a scource inside the structure. Insulating the underside of the roof won't help a lot.
Air sealing any and all penetrations into the attic space is where you need to start. That includes all wireing, plumbing, and hvac pentrations in the attic and basement or crawl space. Several cans of spray foam and some rigid foam boards can do wonders for you. Use the foam board where you have large open chases or soffits, then seal the edges with foam.
Cold roofs work by remaining at or near the same ambiant temperature as the the outside air, but will develope condensation issue even if correctly vented, if the higher moisture levels inside the house are allowed to escape through the attic.