Why Do We Insulate our homes?

Simply put, we insulate to help control heat transfer.

Insulation is all about keeping our buildings and home comfortable. Primarily the comfort is related to temperature, but we also benefit from sound insulation. Several of my customers have mentioned how much quieter their homes are after upgrading attic insulation. Many of those homes are in Tempe, which is in the flight path of Phoenix Sky Harbor airport and if you have ever lived under commercial jets taking off, this benefit may even be greater than the temperature and money saving.


Showing a client where poor insulation is causing her to lose energy in her home.

Insulation is generally rated by “R-value“. This measure the reduction in conductive heat transfer. Essentially how much energy is blocked from moving through insulation with no air flow. I mention the air flow, because it is one of the most common ways for insulation to fail. We’ll get to that in a bit, but if insulation isn’t installed properly, it doesn’t work worth a lick. Anyway, all things being equal, more insulation will block more heat from moving, so upgrading insulation usually involves adding more insulation to your home.

In Phoenix, which is where EcoBuilt Group is based, we have extreme summer heat. Outdoor temps can reach 115 degrees during the summer and most home try to keep their thermostats set at around 76 degrees or so. This sets up a difference in temperature between outside and inside of about 40 degrees. The amount of heat that moves from one place to another is driven by this difference in temperature. That is why we look at upgrading the attic insulation first, because the attic in Phoenix homes is very often up over 140 degrees. This means more energy is going to move from the attic into your home than through your walls, given the same amount of surface area. It is also by far the most convenient and cost effective location to improve insulation R-value in the home.

Energy Saving = Money Saving

I’m sure I don’t need to spend much time on this factor, but the more heat we can keep out of our homes in the summer, the less energy we have to use to keep them cool. Better insulation values mean lower energy bills because we don’t have to use our air conditioners or evaporative coolers as much. The other benefits of cutting down sound and increasing comfort are really where the get into the good stuff. I mean we could all just live in tents out here in the desert and not use any electricity at all, but we pay for comfort, and increasing your comfort while decreasing energy is a double bonus you can get with insulation upgrades.

Insulation Contractor- Quality of Installation is Everything

Unfortunately, insulation doesn’t install itself. More often than not, especially in residential construction, insulation is an afterthought. Most of the time it is put in by the framing crew, but sometimes any number of trades may install some or all of it. With the increasing complexity of buildings; archways, soffits, chases and vaulted ceilings, insulation can be pretty difficult to get right. The general principle is that it needs to be aligned and continuous with the air barrier, which is generally the drywall on a home. Look around your home right now every corner, or edge is a location where there is a potential weak point in the insulation. Thermal cameras help us “see” how well insulation is performing.

Types of Insulation

Fiberglass Batts

Fiberglass Batts re the “standard” insulation that most folks think about when they picture insulation. I blame the Pink Panther commercial that seemed to be all over TV when I was growing up. Funny thing is, I just recently watched a video of that old commercial.

Fiberglass batts can do a fine job of insulating, especially in walls where they are secured in place. In attics, more often than not, they are installed poorly or are moved by a careless contractor so they do not perform well. They are also not usually installed so that they cover the rafters. This means there are “gaps” in the insulation, which lets a lot of heat move through the ceiling.


Cellulose insulation is essentially recycled newspaper, that has been shredded and sprayed with a chemical fire retardant. It does a good job of insulating per inch of thinkness and is blown in, so an even and seamless insulation product is possible. It is a “green” solution in that it is recycled and also helps conserve energy. It is quite dusty when installed, and absolutely requires the use of respirators for filtering air for installers and insulation contractors.

Blown Fiberglass

Blown fiberglass is my preferred insulation to work with. It provides good thermal performance and is affordable. It doesn’t seem to settle over time and lose it’s R-value, and the newer stuff isn’t nearly as itchy as the old fiberglass batts were. There are a couple different brands out there that range in color from white to pink to yellow, but all in all, they insulate about the same, performance wise. Again, how well it is installed means everything. I have dug through 15 inches of insulation to find an open chase that glowing red hot in my thermal images (well, it was 108 degrees internal wall temperatures, close enough). Making sure the attic is prepped to be insulated with blown fiberglass is the key. In retrofit and upgrade situations, this is done with an attic air seal, which we include in all our insulation contractor estimates. If we didn’t insure the insulation we were installing was working properly, we would be wasting your money and our time. Our preferred installer for blown fiberglass insulation gives us wholesale rates so you get the best product for your money.

Spray Foam

Now we are getting in to high performing and somewhat expensive insulation. One of the massive benefits of spray foam is that it creates it’s own air barrier. When we retrofit an attic to spray foam, we typically will apply the foam to the underside of the roof deck, this turns the attic into a semi-conditioned space and lowers the temperature in the attic drastically. This is an important benefit because most of the homes in the valley have duct work and air handlers that are in the attic. Insulating the space they are located in improves their efficiency and also lengthens their useful life.

Spray foam is also a great product for new construction and home improvement additions. We find it to be the highest performing insulation used in residential and commercial construction and is a great choice for folks who want to live in a high performance home. Here is a great spray foam insulation company in Phoenix, AZ

Rock Wool

Rock wool is an older insulation that used to be applied in attic in a blown in fashion. That application has largely gone by the wayside, but it is still available and offers on nice benefit; fire resistance. Most of the rock (mineral) wool insulation that is available today is dimensional and comes in sheets. These sheets off decent thermal insulation, excellent sound insulation and very high fire resistance, so this type of insulation is utilized in special circumstances.


Vermiculite is an older insulation material that often contains asbestos as a fire retarder… Unfortunately, asbestos is nasty stuff and is linked to all sorts of health conditions. Many times it is in attics in older homes, 1960s and earlier and is often covered up by another layer of insulation. This is tricky because getting the stuff out is a potential hazard and leaving it in is a potential hazard. Either way it is best to avoid, but if you find yourself in a home that has vermiculite insulation, please contact a professional insulation contractor in your area that specializes in asbestos removal and remediation. If you are living in a home with even a small air leak that lets air move across the insulation, it can become airborn and find it’s way into your lungs, a situation we all want to avoid.