Dense-Pack Insulation vs. Batts: Which Is Better for DIY? – GreenBuildingAdvisor

Q&A Spotlight

An owner-builder considers using a rental insulation blower to dense-pack his walls, but GBA experts suggest an easier approach

Before the advent of insulation batts, loose fill was the way to go—straw, mud, horsehair, corncobs, and then in more recent times, vermiculite, cellulose, and fiberglass. In the pursuit of more energy-efficient houses, blown-in insulation has become a popular choice for insulating walls and attics. Both cellulose and fiberglass can fill irregular spaces and work around obstructions, while dense-packing wall cavities can also help reduce air movement through the insulation.

Cellulose, made primarily from recycled paper, typically provides around R-3.5 to R-3.8 per inch and has relatively low embodied carbon. Blown fiberglass can provide comparable thermal performance, depending on the product and installed density. Both materials have advantages, and there’s plenty of discussion about their differences on GBA, including this earlier Q&A about blown cellulose and fiberglass.

But dense-packing wall cavities requires specialized equipment and experience to achieve a consistent installed density. That raises an important question for homeowners planning to do their own insulation work: Is dense-pack insulation worth the effort, or would fiberglass or mineral-wool batts be a better choice?

That’s the question facing GBA member “AKZach,” an owner-builder looking for an economical way to insulate his 2×8 walls, framed 24 in. on center. In a recent Q&A post, he asks whether a rental insulation blower could be used to dense-pack cellulose or fiberglass. He’s heard that reducing the hose diameter can help increase pressure and achieve greater density.

His other option is to install R-30 batts. “The local insulation contractor here charges a fortune, so anything I can do will save significant money,” he writes.

The question for this Q&A Spotlight: Is dense-pack insulation a practical DIY project, or would batts be the better choice?

The Forum goes to bat(ts)

The general consensus among forum participants is that…