Increasing utility costs this year can make an old, drafty house feel even worse when you get your bill at the end of the month. Properly sealing your home with weatherstripping will improve the energy efficiency of your home and help keep you warm all winter long. The money you save on your utility bills will easily pay for the materials and time spent on installation. Not only will you be helping your wallet, but you will also be helping conserve our nation’s resources.
If you had a hole the size of a cantaloupe in the middle of your front door, you would cover it up. Most homes have cracks and gaps all the way around the door, and this gap is just about the equivalent air loss of that hole. Weatherstripping can reduce your heating/cooling bills by as much as 30 percent while reducing drafts that can cause discomfort.
Your home may or may not need weatherstripping on every window and door, but there are some ways to find out which ones do. If you can feel cold air coming in around doors and windows on a windy day, you will have your answer. If you aren’t sure, you can check out your windows and doors with a handheld hair dryer and have a helper inside move his or her hands around the seals of the window or door frame as you move the hair dryer. Another way is to purchase a small smoke gun or use an incense stick near gaps to see if the smoke is being sucked into or blown away from them. You can check for air leaks by holding a tissue where you think there might be a draft. The draft, if present, will blow the tissue around.
The US Department of Energy has come up with a list of common places to look for air leakage.
Water and Furnace Flues
Electrical outlets and switches
Attic entrance or access door
Plumbing and utility access
Exhaust and dryer vents
Blower Door Tests
Professional energy auditors use blower door tests to help determine how well the envelope of your home is sealed.
These are some reasons for establishing the proper building tightness:
• Reducing energy consumption due to air leakage
• Avoiding moisture condensation problems
• Avoiding uncomfortable drafts caused by cold air leaking in from the outdoors
• Making sure that the home's air quality is not too contaminated by indoor air pollution.
How Blower Doors Work
A blower door is a powerful fan or set of fans that is temporarily installed in the frame of an exterior door. The fan pulls air out of the house, lowering the air pressure inside. The higher outside air pressure then flows in through all unsealed cracks and openings. The auditors may use a smoke pencil to detect air leaks. These tests determine the air infiltration rate of a building.
Blower doors consist of a frame and flexible panel that fit in a doorway, a variable-speed fan, a pressure gauge to measure the pressure differences inside and outside the home, and an airflow manometer and hoses for measuring airflow.
There are two types of blower doors: calibrated and uncalibrated. It is important that auditors use a calibrated door. This type of blower door has several gauges that measure the amount of air pulled out of the house by the fan. Uncalibrated blower doors can only locate leaks in homes. They provide no method for determining the overall tightness of a building. The calibrated blower door's data allow the auditor to quantify the amount of air leakage and the effectiveness of any air-sealing job.
Preparing for a Blower Door Test
Take the following steps to prepare your home for a blower door test:
• Close windows and open interior doors
• Turn down the thermostats on heaters and water heaters
• Cover ashes in wood stoves and fireplaces with damp newspapers
• Shut fireplace dampers, fireplace doors, and wood stove air intakes.
Source: U.S. Department of Energy
You can make a similar device to a blower door by placing a large box fan, usually 20 to 24 inches, in a suitable window opening. Seal any gaps between the window frame and fan with cardboard and tape. You can also use some fiberglass insulation or blankets as well. With the fan blowing out the window go around the house and check all the windows, doors, and other places listed earlier. The pressure difference will not be as great, and if you have numerous leaks around the home the amount of air coming in through each gap will be reduced and harder to find.
Types of Weatherstripping
There are many types of weatherstripping on the market today. Some older styles are still produced to replace weatherstripping on older doors and windows. The more common types of stripping are as follows:
Pressure-sensitive adhesive foam
Self-sticking spring metal
Foam-filled tubular gasket
Applications for Various Types of Weatherstripping
Pressure-sensitive adhesive foam is the most common do-it-yourself weatherstripping choice. It is inexpensive and easily installed. It comes in rubber, foam, and plastic and in a variety of lengths, and is sold in rolls. This weatherstripping is not permanent, but will last at least one year and may last three or four years. Paint will cause this type of weatherstripping to lose its flexibility and therefore its sealing ability. It can be used on either wood or metal windows and doors.
Installing pressure-sensitive adhesive foam requires the surface to be completely free of dirt and grease which would cause the adhesive backing not to adhere to the unit. This type of weatherstripping should not be applied to moving parts or where there is friction which could cause the foam to detach from the window or door. It works best in compression so it should be installed on the bottom of windows or on the jamb or door stop where the door comes in contact with the opening.
Remove old foam weatherstripping adhesive completely with rubbing alcohol or paint thinner and a rag. The surface should not have any loose paint. Make sure that the surfaces are completely dry before applying the adhesive weatherstripping.
Spring-metal strips come in bronze, copper, stainless-steel, or aluminum finishes. This type of weatherstripping usually comes in rolls, and they include the brads necessary for installation. Although this kind of weatherstripping seems like a simple installation, it does require patience. Care must be taken not to bend the edges of the stripping; and make sure that the spread of the gap in the metal can fill the gap of the window or door. It was more commonplace before rubber and foam weatherstripping came on the market.
Spring-metal weatherstripping fits into the tracks around the windows. Each strip should be about 2 inches longer than the sash so the end of the strip is exposed when the windows are closed. The vertical strips should be placed so the flared flange faces to the outside. The center strip should be mounted to upper sash with flare aimed down, while other horizontal strips are mounted to the top of the upper sash and the bottom of the lower sash with the flared flange facing out. Use snips to cut the spring-metal weatherstripping to size. Attach strips to the window frame. Position strip properly and note any hinges, locks, or other hardware that might interfere. Trim the stripping where needed. Tap in one nail at top and one nail at bottom of strip. Do not put in more nails and do not drive top and bottom nails all the way in. Since some vertical strips do not come with nail holes, you may have to make pilot holes with an ice pick or awl.
Check to make sure strips are straight and properly positioned. Then drive nail in center of strip partway. Add more nails between starter nails. To avoid damaging strip, drive nails flush with nail set. Flare out edge of strip with screwdriver to create a snug fit.
Self-sticking spring metal has a peel-and-stick backing. These are like the standard spring-metal strips just described, but they are far easier to install. This type can fall off over time since it is not mechanically fastened. (Nailed)
The installation is the same for pressure-sensitive adhesive-backed foam and you will need scissors, pencil, tape measure, and rags and detergent.
Felt weatherstripping is an older type of stripping and is very economical. It comes in a variety of widths, thicknesses, and colors. Felt strips are usually nailed in place, but they are also available with a pressure-sensitive adhesive backing. Although it lasts longer than foam, it is not as flexible and can lose its shape over time. Sometimes felt pads are installed along with foam or rubber weatherstripping in the bottom corners of doors. This is due to the fact that the rubber stripping becomes compressed and deformed over time, while the felt will keep its shape.
You will need a hammer, nails or brads, scissors, and a tape measure for installation. Pressure sensitive felt is installed the same way as pressure sensitive foam.
Measure and cut the felt to fit the window. Keep in mind that felt strips can go around corners. Push material snugly against gap; you can use a screwdriver or putty knife to form a right angle. Try not to compress. Tack the ends of each strip first, while leaving room to pry them out. Start at one end and drive a tack every 2 to 3 inches, pulling felt tight as you go. If you find slack when you reach other end, remove nail, pull to tighten, and trim off any excess.
Serrated metal weatherstripping is either felt or vinyl-backed that combines the sturdiness of metal with the application ease of felt. Most manufacturers package serrated-metal weatherstripping in rolls that include brads for installation. Installation is the same as for felt.
Tubular gasket weatherstripping is made of extremely flexible vinyl. It is usually applied outside where it easily conforms to uneven places. Available in white and gray, it cannot be painted because paint causes the tube to stiffen and lose its flexibility. This type of weatherstripping is usually used in commercial applications and when it is installed by the manufacturer on pre-hung doors.
Foam-filled tubular gasket weatherstripping includes a foam core in the tubular part of the gasket just described. The foam provides extra insulating qualities and extra strength. Moreover, the foam-filled tubular gasket will hold its shape better than the hollow-tube type. It should not be painted.
Weatherstripping for Doors
The most common do-it-yourself installation would be to use pressure sensitive foam weatherstripping. This is applied along the top of the door and on the hinge and latch sides. The foam on the hinge side is installed on the jamb and the foam on the top and latch side is installed on the door stop. The door stop is the piece of trim that sticks out from the jamb to conceal the gap between the closed door and jamb. If you have a metal door, you can purchase magnetic weatherstripping which is pressed into a slot along the door stop. The magnet is inside a flexible vinyl casing and will stretch to meet the door if it is slightly warped.
The threshold of the door is probably where most of the air leakage occurs. It usually consists of a flexible vinyl insert in a metal track. Some wood and metal doors come equipped with a track on the bottom into which a rubber gasket is slid. This can be purchased separately and replaced.
If your wooden threshold is worn down to the point where it must be replaced, there are several types of replacement thresholds from which to choose. Most are aluminum and come in standard door widths; however, if your door is not standard width, you can trim the aluminum threshold with a hacksaw. Replacement thresholds will come with installation instructions which vary between manufacturers. If you cannot find a direct replacement, purchase one that is as close to the original one as possible so that you do not have to do much in the way of modifying the door or floor.
Newer wood and metal thresholds have adjustable pieces which can be raised and lowered to seal the gap in the door. They can also be replaced if damaged or worn down.
Removing the old threshold can be time-consuming and may require the use of a flush cutting saw, hammer and chisel to remove the old threshold even with the door jamb. Once the old threshold is removed, install the new wood or metal threshold; be sure to apply several beads of silicone caulk to stop any air and water infiltration under the door. Apply one straight bead near the outside and inside edge of the door on the sill and an S-shaped bead in between them.
Door sweep coming in contact with the threshold
Install a door sweep to seal gap. Most sweeps are attached to the inside of the door with nails or screws. Cut the sweep to size, and close the door. Tack both ends of the sweep to the door, and then install the remaining nails or screws. If you are using screws, pre-drill the holes first. Get down on the floor to look for gaps between the sweep and the threshold. The door sweep does not necessarily need to be installed parallel to the floor; it is more important that the sweep is installed parallel to the threshold. Make sure that the door is not warped at the bottom, which would create a gap, usually on the latch side. If this is the case, you may be able to move the threshold out slightly so that the sweep will touch the threshold when closed.
Some door sweeps slip under the door and wrap around the bottom; they are screwed into the door on both the inside and outside. If you add this type, you may have to remove the door and cut off anywhere from 1/8 to 1/4 of an inch of material. This type would be for an older wooden door that did not have weatherstripping installed when it was hung.
Hopefully this will be a good start to winterizing your home.
U.S. Department of Energy
California Energy Commission - Consumer Energy Center