The Inside Outside Guys: The right sidewall insulation keeps you cozy

Ken Calverley and Chuck Breidenstein
Special to The Detroit News

You’ve heard it forever. Everybody knows it. Even radio “experts” will tell you. Heat goes up.

So, every wise homeowner does the smart thing and jambs as much thermal insulation as they can into their attic.

But the truth goes a little further. Warm air does rise, but heat goes to cold. In every direction, including “down.”

Walk barefoot across that ceramic tile bathroom floor at 2 a.m. and note the floor “stealing” heat from your feet. They feel cold because of this. Walk away and focus an infrared camera on the spot where you just stood, and you  will note a strong heat signature — evidence of the heat you left behind, now absorbed and stored by the tile floor.

Understanding these two dynamics regarding heat movement allows us to anticipate where our homes will lose or gain heat. Remember that while we want to keep heat in during the cold winter months, we also want to keep unwanted heat out in the hot summer months.

Thermal insulation can help stop warm air escaping outside.

Heat moves through either conduction, convection or radiation. We see all three in a home.

Think of conduction as your warm hand touching that cold windowpane. Heat is rapidly conducted from you through the glass.

Radiant heat energy is literally carried to the house by the sun’s rays, stored through 90  million miles of cold outer space. When the rays strike an object, the heat energy is transferred — perhaps to warm that floor in front of the window.

Convection is movement of heat through a fluid, and air is considered a fluid. So, in our homes, heat may be picked up by air moving over the furnace heat exchanger.  The warmed air then moves through the ducts to supply registers for delivery. The heat in this air will migrate to colder surfaces throughout the living space, including furniture, floors and sidewalls.

It has long been required by code that sidewalls in homes have some insulation in them. It has also been more recently required that our houses be sealed up better to keep air from randomly moving through gaps in the construction.

For decades the most popular insulation product has been one that air can actually move through. So even if it slowed conductive heat movement through the wall it did little to slow air movement. That air could be carrying heat and moisture.

And when warm moisture enters a cold wall, the moisture will condense in the wall and become trapped where it can wet materials and contribute to mold growth.

Keep in mind that more heat is lost through air movement than through conduction. It is said that enough air is lost through the average home every day to fill two blimps. That’s air you paid to condition.

What is our solution to this dilemma? Have a good insulation product retrofitted to your sidewalls.

The products we suggest will have both a good R value and function as good air sealers. Spray foams, with R values ranging from just over 3 per inch to 7, are an excellent product. Dense pack cellulose is another great product for this.

While many companies can install additional attic insulation, not all are set up to properly install sidewall product. Too much pressure can affect interior wall finishes, while too little may not fill the cavities.

There are stories out there about unskilled technicians literally blowing the drywall off the walls in the home.

Such product is generally installed from the outside, so a company must know how to work with your siding material to prevent damage. Boring holes through masonry grout lines in brick walls is also an artform to make sure the repaired holes are not visible when the job is complete.

And then there is the issue of making sure all stud cavities are filled so there are no insulation voids.

A good company will perform pre- and post-insulation scans of the walls to make sure they have done a complete job. 

Keep in mind that properly installed insulation literally provides a lifetime of benefit to your home and its occupants. If you are considering such an upgrade, the Guys suggest Ace and Sons Insulation in Southgate. Ace is a retrofit expert that we trust.

 For housing advice and more, listen to the Inside Outside Guys every Saturday and Sunday on News/Talk 760, WJR-AM, from 10 a.m. to noon or contact us at