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Insulation Basics - Part 4

basement ceiling batt insulation installation
Figure 1 Installing batts in a basement ceiling.
  • Insulating Basement Ceilings
  • Insulating a basement ceiling can be an extremely difficult exercise due to all of the wiring, plumbing and central forced air heating ducts.

    It is also difficult to make a basement ceiling air tight due to all of the same items running from the basement to upper floors. It is not necessary to insulate the basement ceiling if the basement walls have been insulated.

    If you do decide to insulate the basement ceiling the best method is to use insulating batts that are not faced. The batts should be the same thickness as the floor joists and completely fill the void between joists. Secure them in place by using wire stays across the joists, as shown in Figure 1.

    Additional information on: Finishing a basement.

  • Insulating a Crawlspace Walls & Ceiling
Installing faced insulation batts on crawlspace walls
Figure 2 - Installing faced insulation batts on crawlspace walls

    If the crawlspace is vented then you must insulate the ceiling area of the crawlspace. If the crawlspace area is dry and not vented then the best insulation method is to install faced batt insulation against the walls (Figure 2).

    The simplest way to insulate the inside surface of a crawl space is to staple faced batts to the rim joists and run the batts down the wall.

    Before installing the insulation attach a polyethylene sheet over the wall and down onto the floor to protect the insulation from outdoor moisture.

    Before insulating the crawlspace area must be dry. If you have moisture on the floor or ceiling you must take the appropriate steps to correct the problem before insulating. If the problem is moisture on the floor or ceiling of the crawlspace, placing a 6 to 10 mil polyethylene sheet over the ground should eliminate the problem. If it is necessary to overlap 2 or more sheets, the overlap should be a 16 inches and there is no need to tape the seams. If the polyethylene sheet does not correct the moisture problem you should seek professional advise.

  • Insulating Exterior Walls
  • Insulating exterior walls is a major exercise that generally requires the services of an insulation contractor. There are 2 material choices cellulose or fiberglass.

  • Dense-pack cellulose insulation is an excellent choice for exterior wall insulation. Dense-pack cellulose not only insulates but it dramatically reduces any air leaks that may be present. To install the dense-pack cellulose insulation the contractor will remove portions of the outside wall siding and drill holes between each of the wall studs. Using a special blower, the dense-pack cellulose is installed at high pressure, as shown in Figure 3. The siding is then replaced.
Installing dense-pack cellulose insulation in an exterior wall
Figure 3 - Installing dense-pack cellulose insulation in an exterior wall

Loose Fill Fiberglass insulation does not reduce air leaks as well as dense-pack cellulose. Both products are installed in the same manor.