CO2 Smackdown, Step 2: Sealing and Insulating

Now that you have completed a home energy audit, your next step is to take its advice, starting with sealing, weatherstripping and insulating your home to keep in the air you pay to heat. The results are far from trivial: Not only can you save $400 or more from your annual energy bill, but on average you'll also eliminate .36 tons of heat trapping gases every year.

What is our CO2 Smackdown? Read the overview.

Savings (annual):
.36 tons of heat-trapping pollutants
$400 from energy bill

One-time cost: $200 for equipment (depending on house size)

Most people can handle sealing jobs if they have good quality caulk (i.e, not too watery, see Equipment below) and learn to handle a caulk gun. Weather stripping is slightly more demanding, but can still be done. Insulating is a more costly and time-consuming task than sealing. While you may be up for adding batting to your attic or stapling up rolls of it in your basement, insulating walls is a job for a professional and may be a significant investment. Whatever your choices, remember that you have a month to complete the job, so pace yourself. You can also claim the cost of materials for a Federal Energy Tax Credit, but unfortunately the cost of installation cannot be claimed. State rebates, however, may offer some relief.



Sealing can be messy work, so practice with the caulk gun and and get used to the pressure needed to apply a steady bead. When you finish applying a bead, remember to release the pressure on the trigger by pressing on the metal tab on the back of the grip. This will avoid wasted caulk and save you time and frustration. Remember that most insulation won’t stop airflow, so seal in advance of insulating to ensure you catch every spot.

Caulk (50 year paintable latex silicone)
Caulk gun
Bucket and water

1. Revisit leaky spots indicated in your home energy audit to locate cracks and holes and check if they need to be cleaned before caulking. Pay particular attention to duct exhausts that open to the outside and any points where pipes or wires pass through walls. Move any furniture or appliances that will hamper your access to gaps between flooring and walls.

2. With your caulk tip cut at a 45-degree angle, apply caulk to all cracks and holes smaller than an eighth of an inch (larger holes may require wood filler or professional work). Hold the tip flush with the surface to ensure the caulk fills the crack without overflowing.

3. Run a damp cloth or finger over the bead of caulk to smooth any excess.

Photo credit: Misha Gravenor

Weather stripping

Weather stripping creates a seal around windows and doors while allowing them to continue operating normally (a vast improvement over sealing windows shut). While there are many kinds, spring metal weather stripping is the most durable type available and comes in bronze, aluminum, copper and stainless steel. Look for products with prepunched nail holes. Whatever your choice, avoid vinyl weather stripping.

Prepunched spring metal weather stripping
Metal door sweep
Nail punch
Tape measure
Metal shears
Folding ladder


Vertical strips
1. Standard double-hung window frames have four vertical tracks, two on each side. Measure the height from the bottom of each track to the top, then cut four pieces to length.

2. Starting at the bottom, with the flared edge facing out, push one end of the weatherstripping upward between the sash and window frame, sliding it upwards in the track until it hits the top of the frame.

3. Nail brads into prepunched holes from top to bottom (as in photograph). Nails should be slightly countersunk with a nail punch. Repeat this procedure for the three remaining tracks.

4. When finished, run a screwdriver along the outside edge to flare the metal spring into position.

Horizontal strips
1. Next, you’ll apply stripping to the top and bottom of the upper sash and to the bottom of the lower sash. Measure the width of each (you may need to work around your window’s lock), and cut three pieces to length.

2. Nail the first length to the bottom of the lower sash with brads, being careful not to break to the panes. Then attach the second and third pieces.

3. Move the sashes up and down; if they meet obstacles, you may need to sink a brad a bit farther.

4. When finished, run a screwdriver along the outside edge to flare the metal spring into position.


Before applying weatherstripping, make sure the door stands plumb and doesn’t sag towards the door frame. If it does, tighten screws in the hinges until any gaps are even. If you aren't able to correct for sagging, weather stripping will be ineffectual, so a contractor may be needed to level the door. 

Vertical strips
1. Measure the hinge side of the door and cut one strip for the full length. On the latch side, measure the lengths above and below the strike plate and cut two strips to length.

2. Start with the hinge side. Position the strip so that the flared end nearly touches the door stop. Tap in brads at top and bottom without driving them all the way in. The strip should be flush with the jamb.

3. Tap in a brad in center, then work your way from the top down, adding brads to the prepunched holes and countersinking them with the nail punch rather than pounding them flush, which can damage the weather stripping.

4. Repeat this process for the strips above and below the strike plate.

5. When finished, run a screwdriver along the outside edge to flare the metal spring into position.

Horizontal strips
1. Measure the top and bottom of door frame and cut a strips to length.

2. Put in the bottom strip first, lightly tapping in brads at both ends and the middle before nailing brads in the prepunched holes and working your way from the side opposite the hinges toward the hinged side. Cut the ends at an angle to fit snugly against the vertical strips.

3. Position the top strip, standing on a ladder to ensure comfort and to allow yourself to approach the task from the most effective angle.

4. Lightly tap in brads at both ends and the middle before nailing brads in the prepunched holes.  Work your way from the side opposite the hinges toward the hinged side, then cut the ends at an angle to fit snugly against the vertical strips.

5. You may wish to install a doorsweep for further sealing, but note that most are made with a PVC vinyl strip; the production of vinyl releases carcingonic dioxin into the atmosphere.


Photo credit: Misha Gravenor


Most home owners will not be eager to apply insulation, though adding batts to your attic space or basement isn’t too demanding. However, where your energy audit indicated need for additional wall insulation and for any other hard-to-access areas, you will want to hire a professional. To find a certified professional, check listings at the Building Performance Institute.

Whether doing it yourself or hiring a professional, preserve your indoor air quality—look for products with no VOCs. There are many formaldehyde-free fiberglass insulation products now available. Ask for no-VOC polyurethane spray foam if you are having a professional inject insulating foam in your walls.

Since insulation jobs are highly variable and demanding, below is a detailed description of insulating your water heater, a job that is readily handled at all skill levels, followed by links to tips on insulating other areas in your home.

Water Heater Insulation

Insulating jacket

For older water heaters, which suffer standby heat losses, purchase a pre-cut insulation jacket (available at most hardware stores)

1. Cut the tank top insulation to fit around the pipes. Tape the cut section closed after the top has been installed.

2. Fold the corners of the tank top insulation down and tape them to the side of the tank.

3. Wrap the insulating jacket around the tank, ensuring that the ends do not meet over the access panels. It may be convenient to have them meet over a temperature/pressure relief valve and overflow pipe if your tank has these on the side instead of the top (otherwise, you’ll need to cut holes for them).

4. Tape the jacket to hold it in place, then secure it with the accompanying belts and check that they do not block the access panels. The belts do not need to pinch the insulation tightly.

5. Locate the four corners of all access panels. Make an x-shaped cut in the jacket from corner to corner across each access panel.

6. Fold the flaps back.

For pipes, use pipe insulation sleeves with the inside diameter matched to outside diameter of the pipe. The seam should be face down on the pipe. Tape it every foot of the pipe's length.

Other insulation tasks

See the ductwork, basement and attic insulation tips at, which also provides a useful guide to calculating how long it will take for additional insulation to pay for itself in terms of savings on your heating bill.


For Federal tax incentives see the Tax Incentives Assistance Project for information about the limits on energy efficient home improvements. For a listing of state incentives, visit the Alliance to Save Energy. Be sure to check out the Department of Energy’s “5 Things You Should Know Before You Claim Your Energy Tax Credit,” which points out that installation costs for insulation costs cannot be claimed when determining your tax credit.

Depending on your income, you may qualify for free weatherization services through the Weatherization Assistance Program. This service is also available to renters.


Unfortunately, while there are many varieties of insulation, there are not many alternatives to actually sealing and insulating your home (unless you consider moving somewhere warmer an alternative). If the cost of hiring a contractor is too high, break the job up into smaller tasks, sealing your home first, then moving on to insulating those areas you can, from your water heater to your attic space to your basement walls.


I have been doing Weatherization for 25 years and have put together some FYI pages for Residential Home's Global Warming Solutions. Many of these are do it yourself green retrofits. This can be found @ Home Energy Loss Professionals (H.E.L.P.)

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