Simply Stated Architecture, P.C.

Preparing for Heating Season - Sealing Drafts in Walls

Continuing our discussion of preparing for the winter heating season, we’ll take a look at sealing drafts. Many conversations about improving energy efficiency for winter heating jump straight into expensive propositions - new high efficiency furnaces, new replacement windows, and extensive insulation. However, studies have proven that much of the heat lost from a building is from the small, cumulative losses. We’ll take a look at some of the DIY steps that you can take before jumping to the larger, costlier propositions.

The four methods of heat transfer are conduction (transfer of energy by contact), convection (transfer of energy by fluid flow of a liquid or gas), radiation (transfer of energy by emission or absorption of electromagnetic radiation), and mass transfer (transfer of energy by movement of an object containing that energy). Of these four, convection is the dominant form of energy loss within buildings as airflow is the most common method of energy transfer within our building systems.

How many of us have heard "Shut the door, are you trying to heat the whole neighborhood!” at some point in our lives? Leaving a door open is an obvious heat loss by convection - our heated air flows right out the door and is lost. Although it is fairly obvious for us to close that door in the middle of winter to keep our houses warm, often we're essentially leaving other doors open in the form of cumulative smaller leaks. These leaks - a crack under a door, a drafty window, an open fireplace damper - are not as obvious to us as an open door, but they add up and combined can easily be as much of a heat loss as that open door - or even more.

The first step is to find your drafts. An energy auditor will use a blower door to depressurize your house and then use a smoke pencil to find drafts. You can do the same thing on a lesser scale given a windy day and an incense stick. Obviously, drafts are going to occur around penetrations in the exterior envelope, so this is where you should focus your attention. Start with the easy items. Make sure that your fireplace damper is closed, that your windows are fully closed and latched, and that your doors latch securely when closed.

From there, for today's discussion we'll focus on a simple task of sealing wall penetrations around electrical outlets and switches at exterior walls. Slowly move the incense around each cover plate on exterior walls, watching for movement in the smoke stream. Be careful around flammable and combustible materials! Catching the draperies on fire while looking for drafts leads to a whole separate set of household concerns!

Even if you don’t find very noticeable drafts around electrical outlets and switches, the solutions are fairly cheap and an easy first step in sealing up your home. To start, your local hardware store has foam seals available to help to seal these areas. It is a simple matter to shut off power to the circuit, unscrew the cover plate, install the seal, and re-install the cover plate without having to worry about messing with the wires. Directions for application are included with the product packaging.


If, when you remove the cover, you find that there is a gap between the electrical box and the surrounding wall, this can be filled with expanding foam sealer. Be careful to trim back the excess foam and to not allow the foam inside the electrical box as this can create a fire hazard. Electrical components generate heat in use and the airspace within an electrical box is an essential component of fire safety. Do not fill the electrical box with foam, thinking that you are better insulating your home! Again, best to shut off the electrical circuit when working around switch and outlet boxes and follow the manufacturer's instructions on the product. As an added precaution, there are fireblock expanding foam sealants available for applications such as these. Although slightly more expensive than the regular expanding foam, using this non-combustible foam adds another level of safety.

Insulating Electrical Box

If you are hesitant about doing this process yourself, Simply Stated Architecture offers consulting on energy efficiency matters for a reasonable fee and can walk you through the process, answer your questions, recommend products, and make sure that you are comfortable in doing the work yourself. If you still would prefer to have a professional do the work, we can recommend people and firms to contact.