Assessing Air Quality

Detecting Air Leaks
  • Doors and window frames
  • Areas where different materials meet [btw brick and woodsiding, btw foundation and walls, btw chimney and siding]
  • Electric and gas service entrances [outlets]
  • Cable TV & Phone lines
  • Outdoor water faucets
  • Where dryer vents pass through walls
  • Air conditioners
  • Vents & Fans


Caulking and Other Air-Sealing Materials

from The Ministry of Natural Resources Canada

 

Within This Page

Air-seal any cracks and penetrations on the inside surface of exterior walls, ceilings or floors. Interior sealing will prevent air from escaping into hidden cavities in the walls and roof. The sealing will be protected from the elements on the inside, and it will be easier to periodically check its condition. Any moisture that does reach that wall space, however, should be allowed to escape to the outside; otherwise, moisture problems might result. It is not advisable to seal the outside surface (i.e., the cold side) of an exterior wall. Caulk only those cracks that will allow water entry. If you are painting the house, try not to plug the joints in the siding and use a permeable (latex) paint or stain. The outside of the walls must be left alone to breathe and dispel moisture.

Caulking Basics

Caulking gun.

Use tubes of caulking compound and a caulking gun for most sealing jobs. Try the grip with a tube in the gun before buying. Some guns may have a trigger spread that may be too large for your hand. The gun should have a shut-off. A thumb release on the gun is convenient since it permits one-hand operation.

If you are doing a complete job, you will need many tubes of caulking – one standard-size tube will make a bead 6 mm (¼ in.) wide and 7.6 m (25 ft.) long

There are several types of caulking compounds available. People often have a bad experience when they first try caulking because they purchase an inexpensive or inappropriate caulking compound. Cheap compounds are difficult to apply and lack durability. Be sure to choose a material well suited to the task. There are many types of caulking, each with specific applications.

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How to Caulk – Step by Step

  1. Identify the areas to be caulked.
  2. Do not try to caulk in an area where the temperature is below 5°C (40°F); the compound will become stiff and difficult to work with. Read labels carefully for storage and application temperatures.
  3. Make sure the area to be caulked is clean and free of dirt, loose paint and old caulking. Replace deteriorated wood and re-nail loose boards. If there are particularly large cracks – greater than 6 mm (¼ in.) – use a special filler such as oakum or a foam backer rod before caulking. Push this material into the crack to a depth equal to half of the crack width.
  4. Cut the nozzle of the tube to a size that will allow the bead of caulk to overlap both sides of the crack. Make the cut square and then break the seal with a wire or long nail pushed down the nozzle.
  5. Push the caulking gun along at right angles to the crack or joint. The caulk is then forced into the crack to fill the gap completely. Make sure the caulk adheres to both sides of the crack and apply sufficient caulk to allow for movement or shrinkage.

    Note: If you plan to caulk around items that are a source of heat (chimney, light fixtures, fan motors, etc.), be sure to use a heat-resistant caulking compound. Silicone or polysulphide sealants usually work well. Special high-temperature silicones are available for flue pipes.

  6. The seal should also be neat. Effective caulking takes practice, so go slowly at first, following instructions on the tube. "Tooling," or finishing the bead, can usually be done with a wetted sponge or finger before the caulk sets, but do not use your mouth to wet your finger!
  7. Latex and silicone caulk can be cleaned off with water before they set. For other caulks, you can try a standard solvent (e.g., toluene, varsol or brush-cleaning solvent) or check the manufacturer's literature. Be sure to release the pressure lever on the gun to prevent caulk from dripping as you move from place to place.

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Other Sealing Materials and Applications

A number of other materials are used to provide an air barrier at different locations in the house. These include specialty gaskets and tapes, as well as sheet materials such as polyethylene, spun-bonded olefin, rigid insulation, drywall, plywood and sheet metal. Installation techniques are critical when using sheet materials as an air barrier. All edges, seams and penetrations in the sheets must be sealed.

Installing a poluethylene vapour barrier.

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Air and Vapour Barriers

It is often possible to install a new air and vapour barrier using sealed drywall as the air barrier and layers of paint or sheet polyethylene as the vapour barrier. Alternatively, sealed sheet polyethylene can be installed on the warm side of the insulation to provide both an air barrier and a vapour barrier. Proper installation is critical (see illustration above).

  • Use wide sheets to minimize seams.
  • All seams and edges should overlap over a solid backing, such as a stud.
  • Run a bead of non-hardening acoustical sealant between the overlapped sheets over the support.
  • Staple through the sheets and the bead of sealant. As much as possible, avoid all other staples.
  • The finish (e.g., drywall) acts as an anchor, securing the seam. If the polyethylene is recessed in the wall, a batten can be nailed over the seam to provide mechanical support.
  • Seal all penetrations. Where possible, they should penetrate at a solid backing such as plywood and be caulked.

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Tips on Sealing Some of the Leakiest Areas

Electrical Outlets

Sealing sockets.

If you notice a draft through an outside wall electrical outlet, it must be sealed. (Some inside wall outlets can also provide leakage paths, so check them as well.) Turn off the power to the outlet by turning off the circuit breaker or removing the fuse. Check to make sure the power is disconnected by turning on a lamp. There are special foam pads, approved by CSA International, that fit between the cover plate and receptacles. You will obtain a better seal if you caulk the gasket before installation. Place child safety plugs in seldom-used outlets. Some foam pads come with a gasket that fits on the safety plug.

If you are installing an electrical outlet during a renovation, get a good seal by placing it in a special plastic box that is available from many hardware or electrical supply stores. Caulk the penetration for the wire, and seal the new air and vapour barrier to the edge of the box.

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Trim Areas (Baseboards, Mouldings, and Window and Door Casings)

Sealing window trim.

Seal areas of air leakage around all trim. In some cases, this can be done easily by sealing all the joints with a flexible caulk that is clear, paintable or of a matching colour. A more effective solution for leaky or poorly fitted trim is to carefully remove the trim and seal behind it. Insulate wide cracks with a foam backer rod and seal them with caulking, polyurethane foam or other suitable material.

If baseboards are removed, you might also be able to caulk between the wall finish and the bottom wall plates and between the plates and the floor.

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Glass Panes

There should be a tight seal between glass and its wood frame. Check the glazing carefully and be certain that all the seals are intact, with no cracks or missing sections. If required, repair them with putty or glazing compound. Putty usually costs less but tends to dry out and crack faster, unless you put linseed oil on the wood first. A glazing compound, on the other hand, lasts longer and stays semi-soft and usable longer. Remove the old putty and apply the new materials with a putty knife. Be sure to press it firmly into the space for a good seal.

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Fireplaces

Outside duct.

A crackling fire makes a room cosy, but what happens when the fireplace is not in use? If the damper is left open, warm air from the room shoots up the chimney. When the fireplace is not in use, close the damper. Take a flashlight and make sure the damper fits tightly. If it doesn't, fix it yourself or have it repaired.

Even with the damper closed, a great deal of heat still escapes up the chimney. Commercially available glass doors for fireplaces are usually not very tight or effective. Ideally, you should also install an outside combustion air duct to the fireplace to improve operation, efficiency and safety. Ask at your local building-supply outlet or wood-burning appliance dealer if a kit is available.

You can also seal off an unused fireplace. Close it up by putting an airtight plug of some sort in the chimney or across the fireplace opening. This can be made from board material that is cloth-covered and provides a good seal at the edges (see diagram above).

Check for air leaks where the chimney meets the wall. (Remove the trim if necessary.) Caulk this joint with a flexible caulk.

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Chimneys

High temperature caulking.

There may be a large gap where a masonry chimney rises through the attic. This space can be partially sealed by stuffing it tightly with pieces of mineral wool batt. Do not use any material that is, or may become, flammable. For greater effectiveness, cut pieces of sheet metal to fit around the chimney. Seal all the joints with a flexible, heat-resistant sealant (see diagram above ).

If there is a factory-built metal chimney rising through the attic, do not insulate closer than 50 mm (2 in.), as this can create hot spots in the chimney lining and can present a fire hazard. Instead, install a collar of metal or other fire-resistant material around the chimney and caulk to prevent air leakage into the attic.

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Attic Hatches

Sealed attic hatch.

Seal the attic hatch exactly as you would seal a door to the outside. Caulk around the frame and between the casing and the ceiling plaster board. Apply weatherstripping along the edges of either the casing or the access panel itself.

Finally, install hooks with eye bolts or some sort of latch mechanism to hold the hatch firmly against the weatherstripping. The hatch itself should be insulated.

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Windows That Are Never Opened

If you don't need a window for ventilation or as a possible emergency escape route, seal it by caulking rather than weatherstripping. Caulking is likely to be quicker, cheaper and more effective. Install a special strippable caulk that can be removed when you want to operate the window again.

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Mail and Milk Chutes

Seal the chute if it is no longer in use. If you use it regularly, seal around the frame and replace the weatherstripping. If the chute cover is on a spring, make sure it closes properly. A drop of oil can sometimes work wonders or, if necessary, replace the spring. Alternatively, you can buy a new cover. Consider closing your mail chute permanently and replacing it with an outside mailbox.

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Contracting the Work

Homeowners can usually do an effective air-sealing job if they have the time and patience and are conscientious about air sealing in areas that can be difficult and uncomfortable to work in, such as the attic. However, professional air-sealers can usually do a much better job because of their experience in locating and sealing leaks. Contractors may be experienced in using a depressurizing fan door (sometimes called a "blower door") with smoke pencils and with specialty caulking and sealants. Many air-sealing companies can also assess ventilation and combustion air requirements and test backdrafting.

Typically, professional whole-house air sealing can cost from $500 to $2,000 depending on the size and complexity of the house and work required. The contract should specify each area to be sealed and the materials to be used.

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Weather stripping

How to Install Weatherstripping Onto Sliding Windows and Doors

From http://home.howstuffworks.com/how-to-apply-weatherstripping2.htm

Installing weatherstripping onto sliding windows and doors presents some unique challenges. We'll show you in this section how to solve the various problems associated with these tasks.

Installing Weatherstripping Onto Sliding Windows

Sliding windows, those in which the sash moves laterally, come in both wood and metal frames. Weatherstrip the wooden frames much as you would a double-hung window turned sideways. If only one sash moves, weatherstrip it and caulk the stationary sash. For metal frames, follow the instructions for weatherstripping standard metal windows.

Special gaskets are designed for sealing gaps in jalousie and casement windows. To weatherstrip jalousies, measure the edge of the glass louver, cut the gasket to size with scissors, and snap the gasket in place. To weatherstrip casement windows, measure the edges of the frame, cut strips of gasket to size, miter the ends of the gasket strips where they will intersect, and slip the strips in place over the lip of the frame.

Double-hung wood windows almost always require weatherstripping, although if the top sash is never opened, you can solve an air leak problem by caulking to seal any cracks. You may find it advantageous to use more than one type of weatherstripping to complete the job. Be sure to follow the correct installation procedures for each type of weatherstripping.

Installing Weatherstripping Onto Doors

All four edges around a door can permit air to leak in and out of your house. In fact, the average door has more gaps than a loose-fitting window. Doors, moreover, don't run in grooves as windows do, so any crack area around a door is likely to be far greater than the area around a window. Weatherstripping your doors can seal those gaps, get rid of drafts, and help to reduce your heating and cooling bills. In this article, we'll review the various types of weatherstripping for doors and how to install them.

Before you start weatherstripping, inspect the door to be sure it fits properly in the frame opening. Close the door and observe it from the inside. Look to see that the distance between the door and the frame is uniform all along both sides and at the top. The distance does not have to be precisely the same all the way around, but, if the door rests crooked in the frame, weatherstripping may make it impossible to open or close. Naturally, if there is great variance in the opening between the door and frame, it will be difficult to fit weatherstripping snugly at all points, and gaps will result.

The cause of most door problems is the hinges. Therefore, the first thing to do is open the door and tighten all the hinge screws. Even slightly loose screws can cause the door to sag. If the screw holes have been reamed out and are now too big to hold the screws, you can use larger screws as long as they will still fit in the hinge's countersunk holes. If even the larger screws won't work, pack the holes with toothpicks dipped in glue, and use a knife to cut off the toothpicks even with the surface. Now the screws have new wood in which to bite.

Sometimes the door must be planed off to prevent binding. If so, you can usually plane the top with the door still in place. Always move the plane toward the center of the door to avoid splintering off the edges. If you must plane wood off the sides, take the door off its hinges, plane the hinge side, and always move toward the edges.

Spring metal is quite popular for door weatherstripping. It works effectively when installed properly and is not visible with the door closed. In the packages designated as door kits, most manufacturers include the triangular piece that fits next to the striker plate on the jamb.

Applying spring-metal strips: Spring-metal strips (V-shape or single) are available in bronze, copper, stainless-steel, and aluminum finishes. Most manufacturers package spring-metal weatherstripping in rolls, and they include the brads necessary for installation. Although this kind of weatherstripping seems like a simple installation, it does require patience. Here's how to install spring-metal weatherstripping around a door:


Step 1: Measure and cut spring-metal strips to size.

Step 2: Position side strips so flared flange almost touches door stop. Trim away metal where needed to accommodate any hinges, locks, or other hardware.

Step 3: Tap in one nail at top and one nail at bottom of each side strip. Do not put in any more nails, and don't drive top and bottom nails in all the way. If strips do not have prepunched holes, make pilot holes with ice pick or awl. Check to make sure side strips are straight and properly positioned.

Step 4: Drive nail in center of side strip but only partway in. Then add nails spaced at regular intervals between ends. To avoid damaging strip, never drive nails all the way in with hammer. Instead, drive nails flush with nail set. Repeat procedure for other side strip.

Step 5: Put top strip in last, and miter it to fit. Flare out edge of each strip with screwdriver to render snug fit.

Applying self-sticking spring metal around doors: 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. Self-sticking spring metal can be used in the same places as regular spring metal. To install the self-sticking spring metal around a door, follow these steps:

Step 1: Clean surface where strips are to be placed. Measure and cut strips to size with tin snips.

Step 2: Put strips in place without removing backing paper. Mark spots for trimming (for example, hardware points and where vertical and horizontal strips meet).

Step 3: Peel off backing at one end and press strip in place, peeling and pressing as you work toward other end.

Applying pressure-sensitive foam: Pressure-sensitive adhesive-backed foam is the easiest weatherstripping to apply, and it is quite inexpensive. Available in both rubber and plastic, adhesive-backed foam comes in rolls of varying lengths and thicknesses. When compressed by a door or window, the foam seals out the air.

As an added advantage, these strips also provide a cushioning effect that silences slamming. Though not permanent, this type of weatherstripping can last from one to three years.

To install pressure-sensitive foam weatherstripping around doors:

Step 1: Select warm day to work, if possible. Adhesive forms a better bond if applied when temperature is at least 60 degrees Farenheit.

Step 2: Clean surface where weatherstripping is to be attached with detergent and water. Make sure no dirt or grease remains. If pressure-sensitive weatherstripping had been previously installed, use petroleum jelly to remove any old adhesive. Dry surface with rags.

Seal the top and sides of a door with adhesive-backed foam weatherstripping.

Seal the top and sides of a door with adhesive-backed foam weatherstripping.
To install the foam, peel off the backing and stick the strip down.
Step 3: Use scissors to cut strip to fit, but don't remove backing paper yet.

Step 4: Starting at one end, slowly peel paper backing as you push sticky foam strips into place. If backing proves stubborn at beginning, stretch foam until seal between backing and foam breaks.

Step 5: Attach strips on hinge side to doorjamb.

Attach strips of pressure-sensitive foam on the hinge side of the doorjamb and on the doorstop.

Attach strips of pressure-sensitive foam on the hinge side of the doorjamb and
on the doorstop. The adhesive backing on the foam will form a secure bond only
when applied to a clean, grease-free surface.
Step 6: Attach other two strips to doorstop. If corner of door catches weatherstripping as you close it, trim top piece of foam on hinge side. Serrated-metal weatherstripping, usually with a felt-strip insert running the length of the serrated groove, also can be used to seal air gaps around doors. To install this type of weatherstripping, measure the length of strips required, and then use tin snips or heavy-duty scissors to cut the serrated-metal material to the proper lengths. Nail each strip at both ends, add a nail to the center of each strip, and drive additional nails every 2 to 3 inches along the rest of the strip.

Creating a weathertight threshold: The gap at the bottom of the door is treated differently from the gaps on the sides and along the top. The wood or metal hump on the floor along the bottom of the door is called the threshold. 



Many of the metal types feature a flexible vinyl insert that creates a tight seal when the door closes against it. Other thresholds consist of one unit on the floor and a mating piece on the bottom of the door. These two pieces interlock to form a weathertight barrier.

In most cases, the threshold with a flexible vinyl insert is the easiest to install. Interlock systems are quite effective when properly installed, but they require a perfect fit or they will not work satisfactorily.

Wooden thresholds often wear down to the point where they must be replaced. This is an easy installation, and there are many 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. Here's how to install a replacement threshold:

Step 1: Remove old threshold. If it is wood, there are two ways to remove it. In most cases, you can pry it up after removing doorstops with small flat pry bar or putty knife, but you must work carefully and slowly. If jamb itself rests on threshold, saw through old threshold at each end.

Use backsaw placed right against jamb, and saw down through threshold, being careful not to scar floor. Once you make cuts, threshold should be easy to pry up. If prying doesn't work, use chisel and hammer to split piece. Metal thresholds are frequently held down by screws concealed under vinyl inserts. Once you remove screws, threshold will come up easily.

A door sweep can create a tight seal when a gap exists between the door and the threshold.

A door sweep can create a tight seal when a gap exists between the bottom of the
door and the threshold. Door sweeps can be made of wood and felt, wood and
foam, or metal and vinyl. All are effective in sealing out drafts.
Step 2: Install replacement threshold by driving screws through metal unit and into floor. If you don't want aluminum threshold, cut replacement from wood, using original one as pattern.

Step 3: Install door sweep to seal gap. Most sweeps are attached to inside of door with nails or screws. Cut sweep to size, and close door. Tack both ends of sweep to door, then install remaining nails or screws. If you are using screws, drill pilot holes first.

A bottom sweep slides on over the bottom of the door; adjustment grooves adapt it to any door thickness.

A bottom sweep slides on over the bottom of the door;
adjustment grooves adapt it to any door thickness.
Some types of sweeps slip under the door and wrap around the bottom. Still another type fits on the outside, with a section of it flipping upward to miss the threshold when the door is opened. When the door is closed, this section flips back down to provide a seal against the threshold. You can adjust this type of door sweep so it renders a snug fit.

Weatherstripping and weather-proofing your doors -- and the rest of your home -- can help keep you comfortable when the weather is inclement. And the good news is that you can make these improvements to your home without having to call a professional.