Insulation Do It Yourself

The Old House Web

Confused about R-values, rolled or blown-ininsulation, vapor barriers and other insulation terms? This series of stories,adapted from the U.S. Department of Energy "InsulationFact Sheet" explains the ins and outs of home insulation -- and may helpyou save significantly on your heating and cooling costs.

Topicscovered in Part 6: Some tips oninsulating * Insulatingwall cavities * Insulatingbasements and crawlspaces *

A do-it-yourself job? Some tips

rolling insulationWhether or not you install the insulation yourself depends on the structuraldesign of your house and the type of materials used in its construction.

Placing insulation in the attic floor is usually easy, requiring only layingthe material between the parallel joists of the frame.

  • Be careful about whereyou step in the attic.
  • Walk only on the joists so that you won't fall throughthe drywall ceiling.
  • You may need to place walking boards across the tops of thejoists to make the job easier.
  • Remember that it is important to seal up airleaks between your living space and the attic before adding insulation in yourattic.
  • Also, bear in mind that insulation placed between joists, rafters, andstuds does not retard heat flow through the exposed frame. This heat flow iscalled thermal bridging and is especially important in houses with metal framesor joists. In attics, thermal bridging can be reduced by adding sufficientloose-fill insulation thickness, or cross-installed batts, to cover the wood ormetal frame as much as possible.
  • In some houses with low-pitch roofs, it isdifficult to gain access to all of the attic floor, so blowing equipment may beneeded to place insulation in relatively inaccessible areas. In most attics, itis easier to get complete coverage with blown-in insulation. It is best to hirean insulation contractor for this job.
Insulating wall cavities: Not a do-it-yourself job

In existing buildings, installing insulation in the cavity of exterior wallsis difficult. It usually requires the services of a contractor who has specialequipment for blowing loose-fill insulation into the cavity through small holescut through the sidewall, which later are closed. It is sometimes feasible toinstall rigid insulation on the outdoor side of masonry sidewalls such asconcrete block or poured concrete. When new siding is to be installed, alwaysconsider adding thermal insulation under it. Generally the services of aqualified contractor are needed to make such installations.

Insulating basements and crawlspaces

The homeowner can often insulate basement or crawlspace walls, or floors overunheated areas, using rigid insulation or batt insulation. Sprayed-on insulationproducts are also available for these locations, but would require a qualifiedcontractor.

  • If you insulate a floor above a crawl space, all ducts and waterlines running below the insulation should be insulated as well.
  • Insulate crawlspace walls only if the crawl space is dry all year, the floor above isnot insulated, all ventilation to the crawl space is blocked, and a vaporretarder (e.g., heavy-weight polyethylene film) is installed on the ground toreduce moisture migration into the crawl space.

Adding thermal insulation to the ceiling or walls of a mobile home is complexand usually requires installation by specialists. However, it is often possibleto add floor insulation to such a home, just as you would for any other type ofhouse.

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