New Home Insulation

Recently I was inspecting a home at the “Pre-Drywall” stage. This is the last time we can see what goes on INSIDE the walls so it is relatively important.

What I saw was not good. My client had paid EXTRA for more insulation, house wrap and other things that were SUPPOSED to save them money in the long run. The insulation contractor had gotten there late in the day and was in a rush to get the job completed so they wouldn’t get fined. Remember this is PRE-DRYWALL; there is no power in the house yet, but they started at about 3:30pm and were still at it when I left, well after dark.

I saw, and documented, enough to have my client insist that the job be-redone by the book.

Insulation Basics

Insulation works to stop the flow of heat by radiation, conduction and convection. If insulation is improperly installed, one or more of these methods on heat transfer will still exist and will cost you money, every month for as long as you own the house.

Insulation needs to be fluffy to work. I think we have all heard that if you compress insulation that the insulative value will be reduced, and it can be reduced substantially.

Insulation needs to completely fill the cavity that it is trying to insulate to be effective and should touch all 6 surfaces. There should be no voids or pockets where air can travel.

Insulation needs to be protected from drafts. Insulation is meant to stop heat, not air. If there is a hole in the exterior sheathing around a fixture, pipe, wire or other penetration, air will come in and disrupt the insulative value of the insulation.

Installing insulation properly takes time, as each piece needs to be the right size for each cavity. Not too long so it is scrunched up at the end. Not too short so there is a gap.  If there are ANY wires, pipes or other obstacles in the way, the insulation needs to be cut AROUND the obstacle so that the obstacle does not compress the insulation and a void is not left behind, or in front of the insulation.

Unfortunately, what I saw was insulation that was stuffed into the cavities, and then stapled to the SIDES of the studs, leaving a vertical channel from the floor to the ceiling. The insulation was often too long and scrunched at the top and stuffed in. It was torn to fit around outlets, and there was no insulation behind outlets and switches (ever wonder why there is a draft coming from that switch on the outside wall?). Insulation was stuffed behind pipes and wires, or on top of them. Overall it was scary.

Oh yes, they had a new guy working, he had done one room “by the book” and it looked GREAT.  The insulation surface was smooth with no voids, gaps or compressions. Each piece was the right length; but he took too long to do it right.

What The Client Paid For

The following is a picture of a NICE WALL…

This is how insulation should look.

What The Client Got

Insulation torn away from around electrical boxes

Batts stuffed into spaces rather than being cut to size

Bats pushed behind pipes, leaving gaps and air channels

The insulation doesn't fill the entire cavity, leaving large air gaps

Even the builder’s PLANS said to face staple…

The builder's installation specifications

…but that isn’t what the client was going to get. In insulation, neatness and precision really, really count.

Thinking About Insulating?

I have put together a collection of the best brochures and technical bulletins on how to install insulation. Download it here (warning: large PDF file — 2.1Mb). This file has information from many different sources, all saying the same thing over and over again, and even using the same illustrations. If you’re in the process of adding insulation, show this to your contractor and insist on proper installation.