Don’t Forget the Fireplace When Winterizing Your Home

Lucas Hamilton

Lucas Hamilton is Manager, Building Science Applications for CertainTeed Corporation

One home feature that is popular because of its charm is the fireplace.  While many homeowners like to have one to provide a cozy room on cold, damp winter days you also have to remember that a fireplace represents a big hole leading up to the sky in your building envelope. If the chimney is not properly sealed when you are winterizing your home your indoor heat will simply go straight up the chimney.

In many homes, the chimney actually accounts for more air leakage than windows and doors.

Many homeowners, like me, don’t use their fireplace during the heating season because it is easy to create a back draft from the fireplace in an air tight home.  If I am using my fireplace and my furnace kicks on it will cause the smoke to back up into the house unless a window in the room is kept open a crack.

When you are not using your fireplace you should make sure that you have a system in place to seal the chimney and make it air tight.  Standard chimney dampers are simply not air-tight enough. There are two methods that could help tighten your chimney:

  • Install a chimney cap that will snug down on the top of the chimney that can be closed and opened by reaching into the chimney and pulling the chain to secure the cap – or release the cap – on the top of the chimney.
  • Install a bladder-like devise that – using the reverse air feature on your shop vacuum – will fill the bladder and create an air barrier.

There are dozens of common sense ways to deal with air leakage from your fireplace.

However, if you do choose an air tightening devise remember to remove it before you use your fireplace or you will have a major smoke event in your home!

Remember, you don’t have to sacrifice charm or aesthetics when working toward high efficiency in the home but you do need to minimize air loss everywhere you can.

Don’t Skimp on Insulation

Spray foam insulationOn February 5, Martin Holladay from Green Building posted a Blog entitled “It’s OK to Skimp On Insulation, Icynene Says.” This was in response to open-cell spray foam manufacturer, Icyene’s position advising builders to install less insulation than the code requires and for building officials to approve insulation that doesn’t meet minimum R-value requirements.

Martin makes some very good points regarding the flaws in this thinking.  Icynene’s position is that air-tightening a home will have a significant impact on the energy consumption of the home–which is absolutely true, but they are also saying that by doing this you can accept lower R-values.  There is no reason to accept lower R-values.  Builders should be able to do both:  air-tighten a home and have the R-values that the code requires.

Heat moves to and from a home in three ways simultaneously; conduction, convection and radiation.

R-value just deals with conduction and not with air loss.  So to say that building code officials can reduce our requirements on conduction because we are helping to deal with air leakage is a weak argument.  Why should we settle for less? The building code requires that homes be air sealed and have a minimum R-value. There is a reason for that. We have to deal with all three modes of heat transfer simultaneously.

Martin points out that there is language in the 2006 International Residential Code (IRC) that gives air sealing requirements.  Here are a few examples Martin publishes about where buildings are to be air-tightened:

  • Sealing all joints, seams and penetrations;
  • Sealing around windows, doors and skylights
  • Sealing openings between window and door assemblies…

These are not places we put thermal insulation. Putting insulation between two studs doesn’t even address what the code language is saying as to where buildings need to be air-tight.  Different measures need to be taken.  If you look at Icynene’s argument you might infer that because they are air-tightening between two studs they can reduce the R-value required between those studs or in the attic.  There is no reason to accept that.

We consumers can and should have both air-tightness and high R-values because energy is too important to have less than what the code requires. 

Lucas Hamilton

Lucas Hamilton

Lucas Hamilton is Manager, Building Science Applications at CertainTeed Corporation.