Q&A Spotlight: Low-Impact Insulation Options for an Existing Home – GreenBuildingAdvisor

Q&A Spotlight

Insulation without demolition—what’s the best minimally invasive strategy to increase insulation in walls?

In the grand scheme of energy upgrades, insulation ranks pretty high, right? It’s versatile, widely available, and can be installed in all sorts of places—inside, outside, above, below. But there’s a catch: Cavity insulation needs to be enclosed to do its job. And enclosing it usually means opening something up. Drywall comes off. Siding comes off. Dust comes out.

So what if you want better insulation, but you’re not exactly in the mood to host a demolition party?

One GBA member, “BlackScreenn,” recently posed that exact dilemma. They want to beef up the insulation in the exterior walls of their older, currently occupied home—but would “like to avoid removing or rebuilding the walls if possible.” Is there an option that is effective and relatively simple to install?

The topic for this Spotlight: What’s the best way to insulate without moving out or tearing the house apart?

Thoughts from our GBA readers and experts

Expert Bill Wichers writes, “That’s like the old joke: Your options are good, fast, and cheap. Pick any two.” He then offers two options that preclude any interior demolition: Add exterior rigid insulation or inject spray foam into the stud bays. Wichers does acknowledge a couple of issues: The former option would require removing the siding, something Blackscreenn doesn’t seem keen on; and spray foam, although less invasive, is harder to control—“sometimes it expands too much, fracturing the drywall, getting into electrical boxes, etc.” He goes on to suggest alternatives that aren’t disruptive but “get a lot of bang for the buck,” such as air-sealing the upper level can lights and the attic hatch, or (if the basement is unfinished) air-sealing and insulating the rim joist.

Member “scottperezfox” relates a cautionary but ultimately positive tale regarding his…