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Cold Crawl Space

Cold Crawl Space Solutions in the Cincinnati Area

Insulating the floors above a basement or crawl space can reduce heating costs

Cold Crawl Space Insulation

After the attic, insulating the crawl space or basement is the next best way to improve comfort and save on your utility bills. Masonry walls have very little ability to resist the flow of heat (R-value). In addition, many basements and crawl spaces are full of air leaks, especially at windows, doors, vents, and around the rim joists and sills that rest upon foundation walls. In an otherwise well-insulated home, heat transfer to the basement can account for up to 30 percent of the home’s energy loss in winter. In summer, a crawl space or basement that is not air sealed and insulated can raise the humidity levels of your home, making your air conditioning system less effective.

There are two ways to insulate a crawl space or basement. Insulation can be installed at the exterior foundation walls; or it can be installed under your first level floors, between the joists. But which is the correct way to insulate under your floors?

Reed's Sprayfoam Insulation can help with these questions. No single solution is correct for every situation. We work with a variety of insulation types, including rigid foam board, spray foam, and cellulose.

Problems with insulating floors with fiberglass

Although fiberglass batts have been stuffed and stapled under the first-level floor in many homes during the past 50 years, its value is questionable. Here are some reasons to avoid it:

  • Coverage is not usually continuous due to obstructions, such as ducts, bridging.
  • Under floor insulation blocks access to plumbing and electrical.
  • Fiberglass batts tend to sag, creating pockets of cold air between the insulation and the underside of the floor above.
  • Fiberglass batt performance can be degraded by condensation, spillage, and plumbing leaks.
  • Fiberglass batts do not maintain an adequate air-seal between the basement and the living space above.

Perhaps an even more important reason for not insulating under the floor is that doing so makes the basement a non-conditioned space, often making the basement cold and damp. If you use the basement as a laundry, workshop, or play space, insulating the walls, not the floor overhead, will make it a more comfortable place to be.

Underfloor insulation over your crawl space

Crawl spaces may look like short basements, but they are very different. They are awkward to access and difficult to use for anything except storage. Crawl spaces often have dirt floors instead of concrete slabs and rarely have windows; nor are they typically used to house HVAC equipment.

Under-the-floor insulation is common in crawl spaces but subject to the same problems listed above. A better approach is to insulate the crawl space with spray foam or rigid foam insulation.

Spray foam or foam board insulation can be applied to the crawl space walls, and the crawl space floor can be insulated with special foam insulation that's covered with a moisture barrier. Perimeter rim joists are sealed. Airtight hatchways, vent covers, and high-capacity dehumidifiers are also available.

We can help decide if underfloor insulation is right for your needs

There are instances when underfloor insulation makes sense. In cold climates, for example, insulating the floor above the crawl space is often more energy efficient than insulating foundation walls. Insulating under floors, however, is not always feasible, especially with existing homes. Plumbing, ducts, bridging, and electrical get in the way. Furthermore, the insulation must be able to resist the degrading effects of moisture. You can’t simply stuff the joist bays with fiberglass batts and expect long-term performance.

Sometimes the underside of a floor is open to the outside. A porch or three-season room may have been enclosed but not adequately insulated below. The underside of a cantilevered section of a house is also open to the outside. Or perhaps the uninsulated/under-insulated floor is over an unheated garage. In such cases, there is no choice other than to use underfloor insulation.