Guide to Mobile Home Roof Insulation

A lot of people, including many insulation contractors, will tell you that you can’t add insulation to a closed mobile-home roof cavity. I can tell you from personal experience that they’re wrong. The best ways to access the roof cavity are either through a hole in the rooftop or by disconnecting the long edge of the roof where it fastens to the wall. Insulating the roof cavity will typically save between 10 and 15 percent of heating and cooling costs and cost around a dollar a square foot, assuming you can find an insulator who will do it..

The insulator should use fiberglass insulation blown with an insulation-blowing machine. Cellulose insulation is too heavy and can corrode the metal roof from underneath. Getting thorough insulation coverage is the most critical part of mobile home roof insulation, and it requires inserting a hose or pipe into the roof cavity. This hose or pipe is attached to the blower hose, which is connected to the blower. Its purpose is to ensure that every cubic foot of roof cavity gets filled with insulation. See Insulation Comparison: Fiberglass and Cellulose for more information.

Cutting a hole in the top requires careful patching, and I always install two patches – the first overlaps the hole and the second patch overlaps the first patch. The first patch is stiff galvanized sheet metal, sealed to the metal roof with roof cement and fastened. The second patch is foil-faced butyl roof patch – one variety goes by the name of “Peel and Seal.” Disconnecting the long edge of a metal roof also involves careful refastening with staples and screws and careful resealing with putty tape or caulking.

Many weatherization agencies working under the Department of Energy’s Weatherization Assistance Program have used these methods for years with great success. You can learn more about the details of these roof insulation techniques in my book, Your Mobile Home: Energy and Repair Guide for Manufactured Housing.

7 thoughts on “Guide to Mobile Home Roof Insulation”

  1. I have a 93 Redman mobile home. The roof attic is a closed system. I am getting wetness in the one bedroom corner in the ceiling. I cut a hole in the ceiling to see what was going on.The wood framing and everything is wet, of course its been very cold here. I put 6 more inches of fiberglass insulation above the ceiling in this outside corner and it still got wet again. Fiberglass insulation is held in place against the galvanized roofing with a layer of plastic and their was a little layer of loose insulation on the ceiling. I tried to vent the roof but this did no good. Can you give me some advice?

    1. Curt. Have you confirmed where the moisture/water is coming from? That should be your first task. Solving the moisture issue at its source.

      If it’s a roof leak (even a small one) then water could be getting and not drying out.

      If warm moist air is leaking from the house and getting into that space when it’s cold outside then at some point on its way out the moisture in the air will condense. That could easily happen when moist air hits the cold roofing. Just like humid air condenses on your glass of iced tea in the summer. The more this happens the more moisture will drain down to the ceiling. Adding more fiberglass insulation won’t stop this from happening. You would need to find out where the air is leaking and seal the air leaks first. Then insulate the area.

      We would recommend that you locate someone in your area that does energy audits. Diagnostic testing, like a blower door test, could help you to locate the air leakage issues and fix them correctly. You may be able to find a local contractor at Good luck and let us know how it goes.

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