Adding Basement Insulation: DIY

portland home energy score basement improvements

What lies beneath? Most Portland homeowners would rather not venture down into their unfinished basements or cramped crawlspaces — the land of spiders, dust, and forgotten holiday decorations. But it might be worth summoning up the courage to do so, especially if there’s a home energy score assessment in your future.

Bottom line is, adding or upgrading your basement insulation can lower your energy costs by up to $170 per year, according to House Logic. It can also increase your home energy score in Portland. It’s one of our top 10 recommended improvements to improve your home energy score. Though the basement or crawlspace may not be the cleanest place to work, this time of year, it’s probably the coolest — so what are you waiting for?

How does basement insulation work?

If your basement or crawl space is not part of the living area of your home, you may be wondering why insulating it is so important. There are several reasons, some of which have nothing to do with energy efficiency.

Interior basement insulation:

  • Prevents access by insects and other critters
  • Reduces moisture intrusion and condensation inside the basement, which can lead to mold and other issues
  • May decrease radon intrusion into the living areas of the home (Portland is one of many cities where high radon levels have been detected in residential areas)
  • Adds soundproofing to floors (the basement ceiling)
  • Stabilizes the interior temperature of the entire home

Basement insulation: Where to put it


Basements are normally insulated in two areas: The ceiling and the walls.

  1. Pick your insulation. Batt insulation is easiest to install. Experts recommend steering away from organic materials to insulate a basement or crawlspace because these areas are especially prone to mold (especially in damp climates like Portland). R-value (insulation efficiency rating) recommendations for Portland’s climate zone are R-11 to R-22.
  2. Installation. This is a project that you should be able to complete over the course of the weekend. Purchase more insulation than you think you’ll need — you can always return unused rolls, and it’ll save you from having to go to the home improvement store covered in dust and cobwebs.


  • Consider wearing a dust mask. Don’t enter a basement or crawl space with an animal infestation — call the experts as the dust created by raccoon dung can be extremely toxic. If your basement is critter-free, just prepare to get dusty, and remember how good that shower is going to feel at the end of the day.
  • Insulate any ducts and water lines in the ceiling area first. See our article on duct insulation.
  • Tuck insulation bats into the floor joists in the basement ceiling. Use wire, fishing line or spring-loaded supports to keep the insulation in place.


If your basement has stud walls, batt insulation can be added here, as well. Just keep in mind that Portland codes may require you to finish those walls once insulation is added.

Consult with a contractor to learn about the scope of your Portland basement wall insulation needs.

Ready to order your home energy score? Call our Portland experts today, or schedule online.