Air sealing reduces drafts and energy bills by blocking the flow of unwanted air. It also increases the performance of insulation and prevents moisture-related problems like condensation and rot.
It’s a simple, cost-effective process that can improve the comfort and durability of your home. But what exactly is it, and how does it work?
Air Leakage
Over time, houses develop cracks and crevices that allow outside air to enter the home or conditioned air to escape. Depending on the weather, these gaps can also carry pollutants and moisture into the house, leading to poor indoor air quality, high humidity levels, mold buildup, and other issues. Air sealing can prevent these problems by closing any gaps, holes, or cracks and filling them with spray foam insulation or blown-in insulation.
While doors and windows are common sources of leaks, the biggest source is often attic penetrations like recessed lighting, fans, and electrical outlets. These openings can lead to warm air escaping the attic in the summer and cold air entering the house through these openings during the winter. Air sealing the attic and reducing these leaks is one of the most important steps in improving home energy efficiency.
Injection foam insulation is an excellent choice for this type of application as it not only blocks air but also stops the passage of moisture vapor, which can contribute to condensation in building cavities and walls. In addition, spray foam and cellulose insulation both have excellent air-sealing properties. Using these materials in the attic, crawl space, and rim joist areas will help to create an effective barrier against leaks and improve your home’s R-Value. This is a major benefit that should not be overlooked as it can significantly lower your energy costs.
Moisture
Moisture is a problem that can negatively impact the performance of insulation. When moisture comes into contact with insulator materials, it creates pathways for electrical current to flow through which reduces the insulation’s ability to stop energy from passing through. It also can cause physical degradation of the material and lead to a decrease in its overall efficiency.
Air sealing keeps conditioned air inside the house and outside air out, saving on utility bills and increasing comfort. The most effective air-sealing strategies involve addressing all the leakage points of a building envelope, which include windows, doors, vents, fireplace flues, and plumbing and wiring protrusions into the wall and ceiling. The most problematic leakage spots occur in the attic and crawl spaces, where the stack effect is often strongest.
There are a variety of ways to address these leaks, from caulking and weather stripping around the edges of windows and doors to installing replacement windows, but the most efficient method is using spray foam insulation. This type of insulation is the only one to offer a complete seal that includes both the interior and exterior walls, as well as the foundation wall and slab, basement walls, and crawl space. This is work that is typically best left to a professional, such as RetroFoam of Michigan. The air seal created by spray foam will eliminate drafts that make rooms feel cold and uncomfortable while making it easier for conditioned air to reach all areas of the home.
Condensation
Air sealing is an essential component of a comprehensive energy-efficient insulation system. Without it, high-performance insulation can be undermined by uncontrolled air flow. Effective air seal blocking minimizes energy waste and makes a significant impact on your home’s comfort.
Air leaks cause a lot of energy loss in a home, and the best way to minimize them is with a combination of air sealing and adding fiber or cellulose insulation. Air sealing closes off all the cracks, holes and imperfections in a building envelope. These are typically in attics, basements and around doors and windows and electrical outlets and switches. Caulking and weatherstripping are common techniques for minimizing air leakage, and many homeowners realize enough savings on heating and cooling to cover the cost of their investment within a year or less.
Another benefit of air sealing is that it prevents moisture vapor from piggybacking through leaking holes. This is important, as a moisture problem can undermine the effectiveness of insulation, and also can lead to mold and mildew. Air sealing can prevent a buildup of moist air, and it’s an excellent first step in insulating a house with fiberglass or cellulose.
An experienced weatherization professional will use a variety of materials to fill in holes, gaps and crevices — rigid foam, caulk, acoustical sealant and spray foam, depending on the location and type of hole. This can be messy work and is best left to a trained professional.
Energy Efficiency
Air sealing and insulation work hand in hand to make your home more comfortable. This pair of upgrades reduces drafts, lowers your energy bills and improves the efficiency of your HVAC system. They are also important for home performance upgrades, such as electrification of your heating and cooling systems to help lower fossil fuel use and reduce carbon emissions.
Leaky walls and doors, gaps around windows, mudsills, and foundations all expose your house to the elements. These leaks waste energy and increase your utility costs. In fact, the EPA estimates that homeowners can save up to 15% on their energy costs by properly air sealing and adding insulation.
Besides keeping outside air out and conditioned air in, air sealing can reduce moisture problems that lead to wood rot and mold, and block outdoor air pollutants like carbon monoxide and cigarette smoke. It can also prevent vapor diffusion and condensation inside building cavities that affect indoor air quality and structure durability.
Air sealing is usually done by a professional using an expanding spray foam that fills the cracks and crevices to eliminate air infiltration. This is messy and labor intensive work that should only be done by a qualified weatherization contractor. It requires getting into crawl spaces and finding and sealing the unique gaps in your house. The benefits are well worth the effort, though, as you enjoy low energy bills and a more comfortable home year round.