Time is running out! We’ve been discussing tips on making your home more energy efficient so that when winter rolls around you can curl up all warm and snuggly on your couch without getting energy utility bills that go through the roof. In Part 1 we identified common locations of air leaks. Then Part 2 discussed preparing and gathering materials. And most recently Part 3 got you going safely into the attic. Are you all set to move forward with your list of energy saving tasks? Good.
Wait! Don’t take a nap yet! Let’s move on to the next phase.
Seal behind the knee walls
If you have a finished attic, then it is likely there are open cavities in the floor framing under the knee walls on the unfinished side of the attic. (Knee walls are the short side walls that drop down to the floor from the low point of the sloped ceiling.) Even though insulation may be piled against these spaces they can still leak air. You should plug these cavities in order to stop air from escaping from under the floor of the finished attic.
Here is a simple tip to do that. Cut a 2-foot-long piece of fiberglass insulation and put in a 13-gallon plastic garbage bag. Fold the bag over so the batt is folded over on itself and then stuff it into the open joist spaces under the wall. If you’re using rigid foam board instead of batt fiberglass insulation, then cut a piece to fit snuggly in the joist opening, and use spray foam to seal the edges and hold it in place. Lastly, push the existing insulation back in place when you’re done.
Seal around furnace flues
Gaps around a furnace or water heater flue or chimney can be a major source of warm air leaving your house and moving into the attic. BEWARE! They may be very hot right now, so be careful working around them! It is best to shut down the furnace or water heater and then let the flue pipe cool down before proceeding with the next steps. Since the flue pipe gets hot, building codes require a minimum clearance to any combustible material and that includes insulation. The clearance is usually a 1-inch space from metal flues, and a 2-inch space from masonry chimneys, but be sure to check your local building codes to be sure.
How can you keep this required space, but still seal air leaks? For round metal flues, cut out half-circle shapes in two pieces of aluminum flashing so they fit tightly against the flue and overlap each other a few inches on either side. Put a bead of high-temperature caulk on the surface that the flue passes through and press the flashing onto it. If the surface is wood, then and staple or nail the flashing into place. If the flue passes directly through drywall or some other thin finish material, then staple or nail it directly into that, if possible, but be sure not to go all the way through. Then seal the small gap between the flue and metal flashing with special high-temperature caulk. This is NOT a place to use spray foam!
The next step is to build a metal dam to keep insulation from touching the flue pipe. Cut a piece of aluminum flashing that is high enough to stick at least 1-foot above the level of the insulation, and long enough to wrap around the flue plus about 6 to 8 inches extra. Then make tabs by cutting into the top edge every inch or so at a depth that corresponds to the gap you need. (For example, do you need a 1-inch gap? Then cut down 1 inch to make the tabs.) After cutting tabs all the way around, then bend the tabs down and toward the flue. That will make sure the insulation dam maintains the required gap around the flue. Next make tabs on the bottom edge by cutting 2 inches deep every inch and bend the tabs out away from the flue. You will use these to anchor the dam to the surface the flue passes through. Wrap the dam around the flue and secure the bottom by stapling through the tabs. Now you can push the insulation right back up against the dam.
Do you have a masonry chimney? Use the same method above, but adapt the shape of the insulation dam to the square or irregular shape of the masonry.
We’re making progress! Stay tuned for the next installment about sealing the small, hidden gaps that can also be a big energy loss.
Do you need help right away with the central heating or cooling system in your house? Call GAMA Air at (310) 651-6936 or use our online form to schedule a visit at a time convenient to you for a service call. We have a 100% happiness guarantee.
Want a quick answer to a question you have? Visit our “Ask an Expert” page and get a quick answer from our resident expert.