For homes that have already been built, we generally recommend starting with the attic or ceiling insulation first because it’s less money to do and you get a bigger return on your financial investment. You tend to get the most heat loss and heat gain through the ceiling and attic assembly. If that’s already been taken care of, or if the ceiling or attic is inaccessible (like with vaulted ceilings or open beam ceilings where there’s no attic space to install insulation), then you’re definitely going to want to focus on the exterior walls.
For exterior walls, we like to use the drill and fill method. What that entails is drilling holes in the wall and blowing insulation into it. We like to use this method because it avoids tearing down the walls and offers much better insulation than fiberglass batting. The reason it’s better is mainly because of the coverage. When you blow it in, it gets into all the spaces in the wall, wraps around electrical wires, wraps around plumbing pipes, and fills irregularly shaped cavities inside the wall perfectly. With fiberglass batting, you’re dealing with the fact that about 40% of framing is non-standard, which means 40% of the insulation has to be custom cut. On a typical house, you only get about 60-70% of the R-value listed on the bag with fiberglass. With a blown-in system, you get 100% of the R-value or very close to it.
When you use a material like cellulose, which we prefer for exterior walls, you also get a very high air sealing factor. Cellulose is dense, and with the dense pack application we use, you get up to 95% air sealing, which is comparable to spray foam that gets 98%. This makes it a very effective system.
We like the drill and fill method because it offers flexible installation—it can be done either from the inside or outside. Some prefer doing it from the outside because it’s more convenient and doesn’t disrupt day-to-day life. If you’re already planning to patch or paint stucco from the exterior, it’s an ideal time to do it. For others, the inside is preferred despite generating dust, which we’ve developed systems to contain and manage. The inside method has a 0% chance of waterproofing issues down the line, whereas drilling through a vapor barrier on older homes can risk long-term water intrusion. We inform our customers of these options before submitting a proposal.
The best time to insulate exterior walls is when you’re planning to paint since painting is necessary afterward. If you’re planning on painting your interior or exterior walls anytime soon, it’s a great time to consider exterior wall insulation.
We like using cellulose insulation for several reasons: it offers better results at a lower price point. Cellulose gets more R-value in the same space than fiberglass, has a higher air sealing factor, and contributes to better soundproofing. It’s also less expensive because it’s made from 80% recycled newsprint and 20% boric acid. In fact, cellulose is the only insulation material in the world with a negative carbon footprint when you factor in the manufacturing process. It’s better for the environment, soundproofs better, is insect and termite resistant, and has better fireproofing properties. Fiberglass won’t catch fire up to 1,000°F but won’t resist it either, while cellulose actively resists fire.
For more information, check out our blog and feel free to contact us for an estimate or more details. There is also a federal tax credit available for this until 2032!