If you have basic insulation in your walls and in the attic, being called upon to strengthen your home’s defenses against the weather with more insulation in the basement and the garage can seem unreasonable. Is all this insulation really necessary? How much heat can you lose if you don’t do anything?

An accessible analogy

If the call to insulate your basement seems excessive, consider the difference between sitting directly on a piece of wood on the floor, and sitting on a cushion on the floor. Heat from your body drains readily when your body is in contact with a good conductor. Homes lose 15% of their heat through their floors, more if their basements are very cold for reasons of local geology.

You can lose even more heat through the attic and roof. Warm air from your heating rises up.

There’s another reason to insulate your attic thoroughly. When sparingly insulated, a lot of heat from the living area can escape into the attic, and warm the roof. If you have snow on the roof, the layer in contact with the roof will melt, trickle down, and form an ice dam on the eaves. This can cause serious damage to your roofing shingles. It can also cause water damage in your attic, which could lead to the need for major repairs.

How does insulation work?

Homes lose heat in a number of ways.


Heat can be lost through building materials such as timber or brick. These are good thermal conductors. The only way to stop such conduction is to place massive amounts of low-density insulation between the interior of the home and the structural surface in contact with the outside. Insulation contains millions of tiny air pockets that work as poor thermal conductors to slow down the transfer of heat.


Convection is the process of heat transfer, in which physical materials such as air or water cycle between areas of heat high heat and low heat to physically transfer energy. While such heat transfer might seem impossible in a home that seems tight as a drum, it does happen. Walls that have poorly installed insulation usually have considerable convection action within.


Homes will radiate heat no matter how well they are insulated with foam, wool or anything else. It takes reflective foil barrier insulation to keep such waste down. Most radiation happens through older windows that do not have double or triple glazing.

Direct thermal bridging

When an interior surface in a home is in direct contact with an exterior surface, the home is said to have thermal bridging. Such contact could occur at various points — metal door or window frames, wall studs, trans-wall rafters and so on. It takes careful separation to achieve insulation.

A thorough insulation solution helps take care of every kind of heat loss. Unfortunately, many insulation projects go after only one or two these methods. While homeowners believe that they have good insulation, they still have many quiet sources of thermal leakage.

Doing a thorough job

According to Applegate Home Comfort, a leading home insulation installation contractor, quality insulation isn’t merely about saving on energy. It is mostly about comfort. Poorly insulated homes can feel uncomfortably cold and drafty even when they have their furnaces running full-blast. They also need to depend on heating solutions for far longer. When neighbors have switched off their furnaces in spring, they may still need them. The fact that there are energy savings is a pleasant bonus.

If your home hasn’t been properly insulated, you might be losing half the heat produced. Depending on the kind of cold weather that you get in your region area and the kind of neighborhood that you live in, there are impressive savings to be had