When it comes to making your home more comfortable and energy efficient, air sealing is one of the most impactful improvements you can make. Many homeowners focus on upgrading their insulation or replacing their heating system, but without proper air sealing, much of that investment is wasted. Air leaks allow conditioned air to escape and outdoor air to infiltrate your home, forcing your HVAC system to work harder and driving up your energy bills.
In this guide, we will explain what air sealing is, why it matters, where air leaks commonly occur, and how professional air sealing can transform your home's comfort and efficiency.
Why Air Sealing Matters
The average American home has enough air leaks to be equivalent to leaving a window open all day, every day of the year. According to the U.S. Department of Energy, air leakage accounts for 25% to 40% of the energy used for heating and cooling in a typical home. That is a significant portion of your energy bill going quite literally out the window.
Air leaks do not just waste energy. They also create uncomfortable drafts, allow dust and allergens to enter your home, can lead to moisture problems that promote mold growth, and make it difficult to maintain consistent temperatures from room to room. If you have ever noticed that some rooms in your home are always too hot or too cold, air leaks are very likely a contributing factor.
In New York City, where heating costs can easily reach $2,500 to $4,500 per year, reducing air leakage is one of the fastest ways to see a return on your investment. Professional air sealing services can reduce your heating and cooling costs by 10% to 20% or more.
What is Air Sealing?
Air sealing is the process of identifying and closing gaps, cracks, holes, and other openings in your home's building envelope that allow air to pass between the inside and outside. The building envelope includes your walls, roof, foundation, windows, and doors. Any penetration through this envelope, whether for plumbing, electrical wiring, ductwork, or simply from age and settling, creates a pathway for unwanted air exchange.
Professional air sealing begins with a diagnostic assessment, typically using a blower door test. This test depressurizes your home to measure the total amount of air leakage and helps technicians identify exactly where the leaks are located. Combined with thermal imaging, this allows for a targeted approach that addresses the biggest problems first.
Immediate Benefits of Air Sealing
Homeowners who invest in professional air sealing typically notice improvements right away. Here are the most significant benefits:
- Lower energy bills - By preventing conditioned air from escaping, your heating and cooling system runs less often and uses less energy. Most homeowners see a 10-20% reduction in their energy costs after professional air sealing
- Improved comfort - No more cold drafts in the winter or hot spots in the summer. Air sealing helps maintain consistent temperatures throughout your home, eliminating those frustrating room-to-room temperature differences
- Better indoor air quality - Air leaks do not just let conditioned air out. They also let unfiltered outdoor air, dust, pollen, pollution, and pests in. Sealing these leaks helps keep your indoor air cleaner and healthier
- Reduced noise - Sealing gaps and cracks in your building envelope also reduces the amount of outside noise that enters your home. This is especially valuable for homeowners in busy New York City neighborhoods
- Moisture control - Uncontrolled air leakage can carry moisture into wall cavities and attic spaces, leading to condensation, mold growth, and structural damage over time. Air sealing helps prevent these costly moisture problems
Identifying Air Leaks: Where to Look
Air leaks can occur anywhere in your home where different building materials meet, where pipes and wires penetrate walls and ceilings, or where components have settled and shifted over time. Here are the most common locations where air leaks are found:
- Attic access hatches and pull-down stairs - The attic hatch is one of the single largest air leak sources in most homes. Without proper weatherstripping and insulation, it acts as a direct pathway for conditioned air to escape into the attic
- Recessed lighting and ceiling fixtures - Recessed can lights that are not IC-rated (insulation contact) create large openings in your ceiling. Each one can leak as much air as having a small hole in your wall
- Plumbing and electrical penetrations - Every pipe, wire, and duct that passes through a wall, floor, or ceiling creates an opening. In older New York City homes, these penetrations were rarely sealed during construction
- Windows and doors - Gaps around window and door frames, worn weatherstripping, and deteriorated caulking are common sources of air infiltration. Even newer windows can leak if they were not properly installed
- Rim joists and sill plates - The rim joist, where your foundation meets the framing of your home, is one of the most overlooked sources of air leakage. In many homes, this area was never sealed or insulated, creating a continuous pathway for air to enter the living space from outside
How to Seal Air Leaks
Different types of air leaks require different sealing methods. A professional air sealing contractor will use a combination of techniques to address every leak in your home. Here are the most common methods:
- Caulking - Used for small, stationary gaps and cracks, such as where window frames meet the wall or where pipes pass through walls. Caulk is best for gaps that are less than half an inch wide and that do not expand or contract with temperature changes
- Expanding spray foam - Ideal for larger gaps and irregular openings, such as around plumbing and electrical penetrations, gaps in the framing, and openings around ductwork. Spray foam expands to fill the space completely and creates both an air seal and a moisture barrier
- Weatherstripping - Applied to movable components like doors and windows to create a tight seal when they are closed. Different types of weatherstripping are available depending on the application, including foam tape, V-strip, and door sweeps
- Rigid foam and metal flashing - Used for larger openings such as chimney chases, flue pipes, and other areas where fire-rated materials are required. Building codes require that certain penetrations be sealed with fire-resistant materials rather than standard foam or caulk
- Gaskets and covers - Foam gaskets behind electrical outlet and switch plate covers on exterior walls can reduce air leakage through these common penetrations. While each individual outlet may not leak much, the cumulative effect across an entire home can be significant
Materials and Techniques
Professional air sealing contractors use a variety of specialized materials and techniques depending on the location and type of air leak being addressed. The most effective air sealing projects combine multiple approaches:
Attic Air Sealing
The attic is typically where the biggest air sealing gains are made. Technicians seal around all penetrations through the attic floor, including wiring, plumbing, HVAC ducts, chimney chases, and recessed light fixtures. This work is done before any new attic insulation is installed, ensuring that the insulation can perform at its full potential.
Basement and Crawl Space Sealing
The rim joist area in basements and crawl spaces is sealed using spray foam or rigid foam board. Gaps around pipes, wires, and ducts that pass through the floor above are also sealed. This prevents cold air from entering the living space from below and helps keep basement insulation and crawl space insulation working effectively.
Wall Sealing
In balloon-framed homes, which are common in older New York City housing stock, air can travel freely through wall cavities from the basement to the attic. Dense-pack cellulose insulation serves double duty in these homes, providing both insulation and air sealing within the wall cavity.
Financial and Environmental Impact
The financial benefits of air sealing are among the most compelling reasons to invest in this improvement. Professional air sealing typically costs between $1,000 and $3,000 for a whole-house project, and the energy savings can pay back that investment in just 2 to 4 years.
For New York City homeowners, where heating costs are already high and rising, the savings are even more significant. A home that spends $3,000 per year on heating can expect to save $300 to $600 annually after professional air sealing. Combined with proper insulation, total savings can reach 30% or more.
Income-eligible households may qualify for free air sealing through NYSERDA's EmPower+ program, which covers air sealing, insulation, and other energy improvements at no cost. This program is available to households earning below 60% or 80% of the Area Median Income, and NY Energy Project is an approved EmPower+ participating contractor.
Beyond the financial benefits, air sealing also reduces your home's carbon footprint. By using less energy to heat and cool your home, you are directly reducing greenhouse gas emissions. Every home that undergoes professional air sealing contributes to a cleaner environment and a more sustainable future.
Common Concerns About Air Sealing
Some homeowners worry that sealing their home too tightly will cause air quality problems or trap moisture inside. These are valid concerns, but a professional contractor addresses them as part of every project:
Will my home be too tight?
In practice, it is extremely rare for an existing home to be sealed too tightly. Most older homes have so much air leakage that even aggressive air sealing still leaves plenty of natural ventilation. A BPI-certified contractor will perform a blower door test before and after the work to ensure your home maintains adequate ventilation. If needed, mechanical ventilation can be added.
What about moisture?
Air sealing actually helps prevent moisture problems. Uncontrolled air leakage is one of the primary ways moisture enters wall cavities and attic spaces, where it can cause condensation and mold. By controlling air movement, air sealing reduces the risk of moisture damage rather than increasing it.
Is it worth it if I am also adding insulation?
Absolutely. In fact, air sealing should always be done before insulation is installed. Insulation works by trapping still air within its fibers. If air is moving through the insulation due to leaks, it cannot do its job effectively. Air sealing and insulation work together as a system. One without the other delivers far less benefit than the two combined.
Conclusion
Air sealing is the foundation of any effective home energy improvement project. It is often the most cost-effective upgrade you can make, delivering immediate comfort improvements and long-term energy savings. Whether your home is a pre-war brownstone in Brooklyn, a colonial in Queens, or a Cape Cod in Staten Island, professional air sealing can make a significant difference in your comfort and your utility bills.
The key is working with a qualified, BPI-certified contractor who understands building science and uses diagnostic testing to identify and verify the work. At NY Energy Project, we start every project with a free home energy audit that includes blower door testing and thermal imaging. This tells us exactly where your home is leaking air and allows us to develop a targeted plan to address the biggest problems first.
If you are ready to make your home more comfortable, healthier, and more energy efficient, air sealing is the place to start. Contact us today to schedule your free assessment and find out how much you could save.
Ready to Seal Your Home's Air Leaks?
NY Energy Project is a BPI Gold Star certified, EPA Lead-Safe certified, NYSERDA EmPower+ participating contractor serving Brooklyn, Queens, Manhattan, the Bronx, and Staten Island. We start every project with a free home energy audit so you know exactly where your home is losing energy.
