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U.S. Department of Energy - Energy Efficiency and Renewable Energy

A Consumer's Guide to Energy Efficiency and Renewable Energy

Manufactured Home Energy-Efficient Retrofit Measures

There are many differences between manufactured (mobile) homes built before

the HUD Code took effect in 1976 and those built afterward.

Many manufactured homes made before 1976 are likely to have the following:

If you have a pre-1976 manufactured (mobile) home,

you may want to make the following energy efficiency improvements to reduce heat loss:

Instead of rolling back the roof, many installers prefer to use roof caps for insulating, in spite of their inferior performance. Roof caps come in kit form and consist of insulation boards, usually of dense fiberglass, with a synthetic rubber or metal covering. Roof caps can insulate the roof to R-19 without disturbing the existing roof. If all leaks in the old roof covering are sealed, the old roof acts as a vapor retarder, eliminating moisture problems and the need for ventilation.

Also, blowing loose-fill insulation into an existing manufactured home is difficult because of the narrowness of the wall and roof cavities. Pre-1976 homes often had only 2" 2" studs (5.08 cm 5.08 cm) (new manufactured houses are required to have at least 2" 4" [5.08 cm 10.16 cm]). Trusses also hinder adding more roof insulation. Rolling back the roof to add insulation can lead to realignment problems and leaks. Furthermore, if the rollback method is used, adding some type of mechanical ventilation system to alleviate moisture condensation problems in the roof cavity may be necessary.

The above energy efficiency measures are based on experiments conducted on pre-1976 manufactured homes by the National Renewable Energy Laboratory (NREL) from 19881991. A survey of 36 mobile homes by the Colorado Division of Housing found that using these NREL-developed retrofit measures resulted in a 31% reduction in heating fuel usage.

To improve your home's energy efficiency, you should also consider the following:

 

 

Insulation Types: Fiberglass vs. Cellulose

Insulating your mobile or manufactured home is one of the best ways to reduce your energy bill and improve your comfort. Fiberglass and blown cellulose are the most commonly used insulation fibers, but it's important to know which is the best option for your home.

Fiberglass insulation is sold as batts or loose fill. Batts are narrow blankets that come in rolls. Batts are installed in walls, floors, and attics. They often have a paper or foil face that helps slow moisture movement but this facing makes installing batts correctly more difficult. Unfaced batts fill cavities better and are easier to cut. If you install fiberglass batts in your wall cavities, cut them accurately to size. Fit them carefully around electrical boxes and wires. A sloppy fit can negate some of the insulating value of fiberglass blankets.

Fiberglass loose fill is installed in attics and wall cavities. It is a good material in moist, humid climates since it absorbs very little water. It's also a good material for retrofitting the wall cavities in metal-skinned mobile homes. Its low density puts less pressure on the ceiling or underbelly, reducing the potential for damage to the structure. Fiberglass loose fill is usually installed by professional insulators. It's easy to over-fluff this material, reducing its density and encouraging heat-robbing air currents. Be sure your insulator installs it at the manufacturer's recommended density.

Cellulose insulation is purchased as a loose-fill material, and is always installed with an insulation blower. It's made from recycled paper that is treated with a flame retardant and pest deterrent. You can purchase it at lumber yards and home stores. You can rent a blower and install it yourself in your attic. Densely packed cellulose creates a better air seal than fiberglass because its small fibers pack into corners, crevices, and small air leaks. Because of this, cellulose is frequently used in the walls of older homes. Cellulose is also cheaper than fiberglass.

You shouldn't install cellulose insulation if you live in a very humid climate since it absorbs moisture easily. This will tend to wash out the fire retardant, decreasing its fire resistance and possibly corroding metal siding, wiring, or roofing.

 

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