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Green Building Blog

7 Steps to an Energy-Efficient House: 3. The Walls

Insulate wall cavities with dense-packed cellulose

Filling the wall cavities. The easiest way to insulate empty wall cavities in an existing house is to blow in cellulose insulation through holes drilled in the exterior sheathing.
Image Credit: Bill Hill


Editor’s introduction: With energy prices rising again, many homeowners are planning energy-efficiency improvements to their homes. But most people are unsure of where to begin, and even seasoned builders don’t always know which priorities should rise to the top of the list. Betsy Pettit, an architect at Building Science Corporation
, recommends starting where you can get the most bang for the buck.

Step 3: Insulate your walls

Filling empty wall cavities with cellulose is a cheap, easy, effective way to warm up an old house. Blowing insulation into existing wall cavities is an art, to be sure, but many contractors have been doing it for years. By checking the quality of the job with an infrared camera, an insulation contractor can verify that all voids have been filled.

If the home’s existing siding is nearing the end of its useful life, it’s possible to install a thick layer of rigid foam on top of the existing sheathing at the same time that the siding is replaced.

This article is adapted from Betsy Pettit’s Remodeling for Energy Efficiency
in Fine Homebuilding


In Green Basics:

Blown-In or Loose-Fill Insulation

Insulating Roofs, Walls, and Floors

In Product Guide:

Blown Insulation

In Community Forum:

Dense-packed insulation

Is dense-packed cellulose an air barrier?

In Blogs:

Cellulose Insulation

Roofing and Siding Jobs Are Energy Retrofit Opportunities


How to Install Rigid Foam Insulation Outside a House

Superinsulating a Home With Rigid Foam


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