Air Sealing

Air Sealing

You deserve to feel comfortable all year long in your house. Air sealing and insulation locks in the warmth you’ve already paid for and stops drafts.

Most Maine homes have hidden gaps where indoor air escapes and unwanted outdoor air gets in. That air leakage makes your home harder to heat and cool, more expensive to run, and less comfortable to live in. Similar penetrations can also introduce basement and crawlspace air that’s been contaminated by moisture, radon, and unpleasant smells into your living spaces.

Evergreen Home Performance is a local insulation and air sealing company helping homeowners throughout Portland, Rockland and the surrounding Southern and Coastal Maine areas fix these problems at their source. Air sealing is an essential part of home insulation upgrades and a cost-effective energy efficiency improvement.

  • Eligible for up to $8,000 in Efficiency Maine rebates
  • Reduce drafts, improve home comfort
  • BPI-certified experts using building science-backed solutions
Hands using an air sealing gun to apply caulk to gaps in attic
air sealing attic

Why Air Sealing Matters

  • Stay warmer in winter, cooler in summer
  • Eliminate uncomfortable drafts
  • Lower your energy bills
  • Improve indoor air quality

Combined with insulation, air sealing creates a powerful barrier between the living spaces in your home and the outdoors.

In addition to energy waste, leaky homes often pull in air from crawlspaces, basements, attics, and wall cavities—along with dust, mold spores, radon, and other pollutants. Sealing leaks gives you more control over your indoor air quality and along with proper ventilation can create a healthier, safer environment for your family.

How We Find the Leaks: Blower Door Testing & Thermal Cameras

Many times newer homes, including really nice ones built before Maine building codes adopted a blower door testing standard, are leaky due to confusion about roof venting and side attics. If you have a newer home and the floor over the garage is cold or pipes freeze in the master bathroom, you could have an air sealing problem that can be diagnosed with a blower door test.

Blower door testing and thermal imaging cameras show us exactly where the air is escaping. We use this building science technology during our energy audits so we can seal the right spots for real results. We then run a blower test again after work is completed to confirm the difference your upgrades made!

Evergreen Home Performance Team Air Sealing Attic

Evergreen – The Leading Air Sealing & Insulation Company Near You

  • More than 4,500 Maine homes improved since 2006
  • More BPI-certified professionals than any other Maine contractor
  • Over 15,000 home energy audits completed
  • More Efficiency Maine insulation rebates secured for customers than any other contractor in 2024
Evergreen Home Performance Team Air Sealing In Attic

Attic Air Sealing

Attic air sealing helps slow the stack effect, where warm air escapes out of the top of your home and cold air is pulled in from your basement or crawl space to replace it.

Common areas we air seal in Maine attics include:

  • Attic hatches and access doors
  • Chimney chases
  • Side attics (particularly in Cape Cod-style homes of all ages)
  • Lighting fixtures, fans, and vent penetrations
  • Plumbing and wiring penetrations
  • Wall top plates and framing joints

After air sealing, we blow in cellulose insulation for comprehensive attic protection.

Basement & Crawlspace Air Sealing

Your basement or crawlspace is another major source of air infiltration and leaks in your home. In these areas, we often use some combination of rigid foam board and foam gun insulation, which is both an insulator and an air sealant, giving you maximum protection as well as moisture resistance.

Common areas we air seal in Maine basements include:

  • Rim joists
  • Foundation walls
  • Bulkhead doors and access hatches
  • Chimney chases and other floor penetrations
  • Gaps around pipes, wires, and vents

Air sealing and insulation is just one component of our basement waterproofing services. When combined, these solutions not only stop air leaks but also protect your basement from moisture and mold.

Encapsulated Crawl Space
Evergreen employees in attic

Airtight & Healthy: Why Ventilation Matters

As we reduce leaks and block outdoor pollutants with air sealing, we also make sure your home has enough airflow and proper ventilation. Without it, moisture and everyday pollutants originating inside your home—from cooking, showering, or just breathing—can build up.

This additional step ensures your Maine home is not just efficient—but safe, healthy, and comfortable too.

Save On Air Sealing with Efficiency Maine Rebates & Other Incentives

We helped more Mainers qualify for Efficiency Maine insulation and air sealing rebates than any other contractor in 2024!

  • Up to $8,000 in Efficiency Maine rebates
  • Financing with payments as low as $50/month through Efficiency Maine Green Bank and NEIF

During your free consult, we’ll tell you all about available Maine energy efficiency loans and rebates, helping you maximize your savings.

Evergreen Team Reviewing Tax Credits and Incentives With Homeowner

Ready to make your home feel as comfortable as you want? We’re here to guide you every step of the way. Call 207-594-2244 or contact us today to book your free consult.

Take charge of indoor drafts and expensive energy bills

Evergreen is your guide on the path to a better home.

Evergreen did a fantastic job insulating our 1930's home. The onsite team was professional, clean, and really just a joy to interact with throughout the process. A blower test at the end showed a significant decrease in air leakage. I highly recommend Evergreen.

Kristen H.

South Portland

Evergreen did everything they said they would and more. I actually don't mind going into the basement now since they sealed it. The air quality in the house is noticeably better and it's warmer in the winter. We can even store clothing down there where before, whatever was in there would mildew. Even the spider population declined! I used to vacuum so many of them from the corners of the ceilings in the house. Not any more!

Loriel Van Dusen

We couldn't be more pleased with the easy, professional, high-value service from Evergreen. Having purchased an older home that had been in our family for generations, we needed multiple upgrades, including insulation throughout. Evergreen insulated our attic with blown-in cellulose, built a new, super-insulated attic hatch, sealed off the old one (which was just a piece of plywood in a closet ceiling), and also talked us through our best options to upgrade our heating system given the plans we have to add onto the house.

Tom G.

South Thomaston

Greetings one and all! I am writing to express my gratitude to all involved in my insulation project.  From start to finish, I appreciate the universal theme which was maintained by each and every one of you, to ensure that my home was insulated and protected from freezing pipes as if it was your home. Andrea, thanks for helping me navigate my way to the project. Nate, thanks for the thorough initial assessment and the time you took to explain this project to me, step by step. Brian, thanks for setting up my project - so happy

Michele

We are so pleased with the work the team from Evergreen Home Performance did in our home. The project included encapsulation of our basement with a reinforced vapor barrier, installation of a sump pump, spray foam insulation on the walls and insulation of the heating duct work. Everyone at Evergreen was friendly and professional. The project was completed on time and in budget. Our home is much cozier and warmer since the project was completed.

Linda Metzger

We just finished a large project of air sealing and reinsulating our 1890s basement and attic which had been completely renovated 8 years ago but still felt cold and lacked proper energy assessment and corrections. We met with Justin in December and were very impressed with his knowledge, professionalism and communication skills and knew Evergreen was who we wanted to work with. Dave was our on hands project manager and was excellent. The office staff has been quick to respond and helpful as well when needed.

Emily Gallant

The Evergreen team was amazing from initial assessment and planning to the crew that came to complete the work. Our basement encapsulation is the best money we've spent on our house by far. The work was thorough and high quality. And what a wonderful group of people to work with. I highly recommend Evergreen!

Martha Bracy

First we have Evergreen do a BIG project worth about $20K (windows, basement, insulate & rebuild an entire wall, a door, attics, and air sealing). They were so great we had them come back later when we decided we did want to do our other door. They are professional and do great work. They take care of your home and are trustworthy, and on top of all that friendly! I highly recommend you call them!

Garreth C Debiegun

A thorough inspection of our (older) house and its energy needs. Competent and personable work crew.

Jacob Watson

I waited a year to write this review. Evergreen finished our job late last winter. Terrific results!!! we've gone from 12-day propane deliveries to 30+ day propane deliveries. The house is noticeably warmer. The Evergreen crew was/is professional, prompt, thorough, scientific, gracious and immaculate with respect to keeping our house clean. Money well spent.

John E.

Boothbay

We are thrilled with the job Evergreen did to transform our 213 year old home into a warm, draft-free, cozy space. The entire team led by Bruce was prompt, courteous, knowledgeable, and hard working. If Evergreen could transform our home in this way, we are sure they would make a comparable difference in YOUR home!

Jonathan M.

Bridgton

The Evergreen crew who installed insulation in my attic were fantastic! They were very professional, worked exceedingly hard, and they did an excellent job. They were very pleasant and friendly to be around. They cleaned up beautifully after each work day, and left my home in great shape on when they walked out the door for the last time. I can't believe they were able to accomplish all that they did with heat soaring into the 80s and 90s. It was pretty unbearable up there! They have my highest praise and my gratitude.

Cynthia F.

South Portland

Led by Brian Robinson, the Evergreen Home Performance team just completed an insulation refit at my home. It was truly a great experience from start to finish, a period of time that was a fraction of the time that I originally anticipated due to the team's unbelievable work habits and professional knowledge of their tasks. As impressive were the communication skills and friendliness of each and every member of the team.

Anne W.

Rockport

Nothing but good things to say. The guys that came and did the actual work were extremely nice and did a great job. The energy audit was thorough and I was presented with multiple improvement options, I was even given ideas for improvement that Evergreen didn't offer. I never felt like I was being "sold".

Ryan Adams

Evergreen came out 2 years ago to do an assessment and insulate our roof. This year we had them come back and do the basement as well. They are hands-down the best crew we've ever hired to work on our house. They are experts at what they do, and super meticulous in their work. After working in our house for a week with blown insulation, there was no trace they were ever here. We've seen a huge decrease in our energy bills while at the same time the house has become way more comfortable. Can't recommend them enough.

RC Lations II

Portland

Portland Buy Local
Efficiency Maine
EPA Lead-Safe Certified
Building Performance Association
BPI Certified