There can’t be a cheap and effective measure to ensure longevity of basement walls than proper Air -Sealing in basements. Besides, it also helps conserve energy. Basement air sealing prevents warm heated air from escaping and cold winter air from entering the heated space. By this method minor cracks or openings of the building are sealed using weather stripping, foam, caulk and other materials. According to the American Department of study, basement air sealing lowers space heating consumption by 18 to 30 percent.

HOW AIR INFILTRATES

The external cold air enters the house through various wide and hairline openings and cracks during thewindy or cold weather. Irrespective of the fact that  the basement is old or new, the best recommended strategy is to reduce air leakage to the greatest extent by maintaining  controlled ventilation.

PRIORITIES

Though outside walls, doors and windows are the main source for air leakage,  small cracks and openings hidden from normal view permits air leakage considerably. Many homeowners are unaware that cold air leaks into the house through small openings around the window frames and doors and even through chimneys and fireplaces. External air also enters living space from other unheated portions of the house, such as crawl spaces, basements and attics. Also known as bypasses, these pathways and openings connect the house to the basement, crawlspace or attic. To effectively reduce the air-infiltration, it is important to seal the big cavities, followed by penetrations and large cracks and the smaller seams and gaps.

AREAS THAT NEED TO BE WATCHED FOR AIR LEAKS

Air enters the building through cracks in ceilings, floors or walls, where the two walls meet and where the wall meets the interior door frame or ceiling. The other openings to watch out for include gaps through and around switch boxes and electrical outlets, recessed cabinets and lighting fixtures. One also needs to check the false ceilings such as bathroom soffits, kitchen soffits and pull-down stairs.

 Shower stall units and behind the bath tubs, plumbing connections, various floor cavities of finished attics located adjacent to several unconditioned attic spaces.

Often, these over-looked gaps of the house are more responsive to air leaks than the greater and obvious fissure found around doors and windows. As most leakage paths are driven based on the tendency of warm air to rise, very often, it is the attic that is the best and easiest place to stop the leaks. Before working on the attic insulation, sealing the leaks is highly important as the insulation would hide them, making them less accessible and the receptive points for external air. Air can blow in to the house if the cracks are not sealed prior to insulation thereby not allowing the desired level of energy savings.The dust carried by the external air stains the insulated area thus indicating the presence of cracks in the building.

Below are some openings to look out for:-

 Top openings of wall cavities of interior partitions, situated  in and around chimney

 Around the entry door or attic trap door

 Areas above dropped ceilings and staircase ceilings, in and around the pipes (look behind your toilets and underneath your sinks) and

 Ducts penetrating the attic floor or wall

 The other areas to watch out for leaks are situated in the ductwork, wiring penetrations, plumbing chases through top plates of walls and in-between conditioned and attic space

 Bypasses happen at the framing’s key junctures (like attic-to-knee wall transitions), allowing huge quantities of air to leak in and out of the house. The band joist for door rough openings in the walls, windows, exterior sheathing, and drywall are primary spots for air leakage. The right materials are to be used to seal the leaks permanently.

WHICH MATERIALS TO BE USED

Many materials are available from home improvement stores or local hardware stores to seal the air links. To apply, you can use a combination of various air-sealing materials. Below is the list which offers guidelines and description to utilize the materials.

CAULK

It seals less than ½” gap. Select the grade (high temperature, exterior, interior) based on the area of application and go through the  cleanup and application information instructed by the manufacturer. .

SPRAY FOAM

Helps fill small holes and large cracks. It could be messy if not very careful. Latex-related foams are the best suggested in spray foams. It is advised not to use this near flammable areas of the building.

BACKER ROD

Rope caulk or closed-cell foam. Simply press into gap or crack with putty knife or screwdriver. Very often, the backer rod is used along with door rough openings and cracks around window sill.

 House Wrap: This is usually installed over exterior sheathing. It needs to be sealed with caulk or house wrap tape which forms airtight seals. Though it resists water, it isn’t a vapor barrier.

 Insulation: Several forms of insulation could be utilized to stuff large bypasses or holes only when they are used with various other air sealing materials.

 Sheet goods (rigid foam, drywall and plywood insulation): These materials help to form air barriers. Usually, the air leaks at unsealed penetrations or seams.

 Sheet metal: This is used with high temperature caulk to seal various components such as chimneys and flues.

Polyethylene plastic: These inexpensive materials, when used for air sealing purposes, stop the diffusion of vapor. For effective air barrier, all penetrations and edges need to be completely sealed off. As poly tears easily, it has to be well placed to prevent the warm inside air from penetrating out through the ceilings or walls.

 Storm window Kits: These are available at any hardware or home improvement store. You can easily apply them over leaky windows.

 Weather stripping: You can use them to seal various moveable components, like attic accesses, windows and doors.

 Foil-faced or mastic tape: This seals all duct connections, joints and air handlers. For clean surfaces, always apply foil tape.

Using the above mentioned air-sealing materials, you can treat the below mentioned areas:-

 Upper portions of wall cavities of interior partition wall – Just staple plastic sheets over openings and seal them near edges with high quality caulk material.

 Around chimneys – pack gaps around insulated chimney with unfaced fiber glass insulation or rock wool.

 Avoid sealing hot and bare flue pipes with various combustible products.

 Around the entry door or attic trap door – just weather strip the edges. On the attic side of the door, place rigid foam insulation.

 For areas above dropped ceilings and staircase ceilings – simply staple plastic sheet over openings, sealing them with high quality caulking material around the edges.

 Look around the pipes (behind your toilets and under the sinks) and ducts penetrating the attic floor or wall – tightly packed insulation into gaps. You can also fill the area around it with polyurethane foam.

 On some occasions, the joints between floors and walls permit easy passage of air between the outdoor attic area and the heated part of the house. You can easily search for these joints in the space over porch ceiling or in the attic.

 Generally, these air leakage paths are found in Cape Cod type houses or in those instances when the attic space is transformed into living space. Similar arrangements take place when the second floor of three floored house appear larger than the ground floor, with overhand outdoors.

 A large source of air leakage is the joints located between the side walls and porch roof. If you can reach such areas, you can stop the leaks by covering the openings with plywood.

 If you find the areas difficult to reach, you can reduce the air leakage greatly by injecting foam insulation or high density insulation to the joints, reducing their air pathways.

 And, if the windows leak excessively, consider installation of plastic storm window kit, which is inexpensive and easy to install.

AIR SEALING

Before weather stripping, adjust the door to improve the seal. Also check the catch plate to ensure that the door shuts tightly against weather stripping. In an area where the floor meets the door, see to it that the threshold is adjusted to minimize infiltration. If the threshold isn’t sealed properly or is missing, you can install the weather seal. To improve door seal, simply install the door sweep. Though storm doors are advisable, they won’t be cost effective like storm windows. Duct leaks help reduce the amount of cooled or heated air which gets delivered into living spaces. In several older houses which have forced – air furnace, nearly 20 % of heated air is wasted through leaks, without getting delivered to the living spaces.

As compensation, homeowners simply turn the thermostat up, to receive the heat they require, which unnecessarily raise their heating bills. A highly effective conservation measure would be to seal all the duct leaks. While sealing the ducts, you can ensure that you use proper foil tape or mastic tape. The fabric type duct tape turns out to be highly ineffective as the adhesive dries after six months.

Homeowners can stop leaks from doors and windows either by weather stripping and caulking or by simply installing the plastic storm window kits from home improvement or hardware stores. Sealing of basement air leaks need attention to detail as even small leaks may cause significant loss of heat. Adequately sealed homes offer a comfortable environment, saving energy and unnecessary hassles for homeowners. If you feel that you are spending much on your electric bills in the event of heating your house, think about a professional who can help you identify and fix the concealed gaps and help you save energy.

If you are a resident of Pennsylvania suffering from basement problems, call us at 800-771-3244 or visit us at http://www.keystonebasementsystems.com/about-us.html.

You may also contact Aaron Stull -IAQA expert on the official IAQ site: - Email Member

“Keystone Basement Systems, Inc. is a foundation repair company. KBS is not, however, a engineering firm and should not be considered as such.”

Tags: Basic information, Construction, Expert Advice, Informative

This entry was posted on Thursday, November 26th, 2009 at 2:31 pm and is filed under Advice, Basic Information, Remedial measures. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.