Basement Insulation Solutions & Basement Air Sealing

Basement Insulation Solutions & Basement Air Sealing

Without proper insulation, your basement can allow:

  • Heat to escape, driving up energy bills

  • Moisture and soil gases like radon to rise into the air your family breathes

House in the snow with no air leaks

Why Basement Insulation Matters in Maine

In Maine’s harsh climate, your basement is the foundation of your home’s comfort, efficiency, and air quality. Many Maine homes—especially older ones—struggle with air leaks, bulk water intrusion, radon risks, and a lack of insulation. 

At Evergreen, insulation is part of our comprehensive basement waterproofing services. Depending on your home’s age and construction, we may recommend insulating the perimeter foundation walls, the floor system above your basement, or both.

The earth beneath your basement stays around 55°F all year long, and early settlers hand-dug foundations to take advantage of that natural shelter. Today, we pair that time-tested knowledge with modern building science to keep your basement dry, insulated, and protected from soil gases.

For nearly two decades, Evergreen Home Performance has helped insulate and air seal basements throughout Southern and Coastal Maine, including Portland, Rockland, and more, creating a healthier home from the ground up.

Maine basement insulated with spray foam insulation

What Kind of Insulation Works Best in a Maine Basement?

The right insulation for your basement depends on your home’s age, foundation type, and your goals for comfort and efficiency. At Evergreen, we offer a range of solutions to meet your needs, all of which qualify for Efficiency Maine rebates:

Spray Foam Insulation

  • Best for older homes with stone or rubble foundations
  • Creates an effective air and thermal barrier
  • Typically applied from the underside of the floor system at the sill down to 2 feet below grade
  • Overlapped with vapor barriers during encapsulation or waterproofing for a continuous seal

Learn More

Rigid Foam Board Insulation

  • Best for modern poured concrete or block foundations
  • Mechanically fastened to the wall for a durable, continuous insulation layer
  • Installed from the top of the foundation down to at least 2 feet below grade
  • Often combined with vapor barriers as part of a comprehensive waterproofing system

Learn More

Cellulose or Rockwool Insulation

  • Often used when homeowners prefer to avoid spray foam
  • Dense-packed into floor systems
  • Combined with air sealing to reduce leaks between basement and living spaces

Learn More

Evergreen team going through basement

Where & How We Insulate Maine Basements

We tailor each project based on your home’s specific needs:

Foundation Walls

  • Insulated from the sill plate down to at least 2 feet below grade
  • Reduces heat loss and keeps basement temperatures more stable

Floor Systems

  • Insulate and air seal floor cavities above basement or crawlspace
  • Type of insulation used depends on plumbing, wiring, and accessibility
  • Materials include spray foam, dense-packed cellulose, or rockwool

Crawl Spaces & Encapsulations

  • Insulation—especially spray foam—is overlapped onto a vapor barrier for a continuous protective seal
  • Controls moisture, air leakage, and soil gases like radon

Best Basement Practices: Insulation + Moisture Control

Basement insulation works best when part of a comprehensive basement waterproofing strategy, which includes additional measures specifically designed to combat moisture, including:

We’ll help you identify the unique needs of your home and prioritize the right steps in the right order.

Maine basement
Evergreen team walking through basement

Your Trusted Maine Basement Insulation Team

We’ve helped thousands of homeowners in Portland, Rockland, and across the coast create homes that are warmer, healthier, and more efficient—starting in the basement.

  • Efficiency Maine insulation rebates up to $8,000
  • Federal tax credits up to $1,200/year for insulation and air sealing
  • Financing as low as $50/month
  • 4,500+ homes improved since 2006
  • Deep expertise in building science and energy performance

Let’s figure out what your basement really needs—so the rest of your home can finally feel the way it should. Call 207-594-2244 or contact us online to schedule your free consult.

Keep comfort in and energy bills low—take control of your basement with new insulation and air sealing!

BOOK YOUR FREE CONSULT TODAY

Our house still the most efficient home we’ve ever lived in. And we have you folks to thank for that! A special howdy to Brian Robinson please!

Bruce O’Donal and Eva Butler

Evergreen has a professional and reliable team of people who do excellent work. If you want the best of the best in the area, select Evergreen to accomplish your insulation needs.

Mary E.

St. George

I cant say enough about this company and the benefits that it created for our family. They are very professional and have effectively re-insulated our home. The heating bill proves the point.

Bob O.

Springvale

Evergreen did an amazing job insulating our historic home. Their professional staff worked hard to ensure the tough areas in the attic were covered, and clearly communicated their progress. We are seeing the results with our discounted heating bills. Thank you, Evergreen!

Melissa Knoll

Portland

I cannot say enough great things about working with Evergreen Home Performance. Everything including the initial consultation, the fabulous work crew, the office support and the final resolution was handled in a caring and professional manner. My only regret is that I did not know about them earlier. I enthusiastically recommend Evergreen to anyone with concerns about home energy use.

Darlene R

Bath

I had gotten estimates from several other companies, but Evergreen was in another league entirely with their professionalism. If you want the job done correctly, I couldn't recommend this company enough.

Rayna Mayo

Freeport

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

Really great experience from start to finish with Evergreen. They helped us prioritize what needed to be completed first, and has made a significant difference in our hearing costs already. Plus they were really friendly and considerate to work with!

Amy W.

Kennebunk

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

Evergreen completed the work at my home thoroughly and professionally. An inspector from Efficiency Maine came to inspect afterwards and described it as "state of the art" and "outstanding". The crew was very pleasant and considerate during the project. Their cleanup each day was perfect. Communications with the office were easy and reliable. I am very satisfied.

Catherine H.

South Portland

I have always been impressed by the high level of service, quality of work, and excellent follow-through provided by Evergreen Home Performance in the three projects that they completed at the Wells Reserve at Laudholm over the past several years.

Paul D.

Wells

I highly recommend Evergreen! 1st, I had a home efficiency inspection (that was free) & Bryan P. was great! He took the time needed, asked & listened to what I thought were priorities, explained clearly what he thought were priorities & why, then gave me numerous options. No pressure whatsoever. Then I had my attic sealed & insulated as the 1st step & Bryan came along on day 1 to introduce everyone & make sure we were all on the same page. Bruce's team (inc. Kelsey & Roland) did the work - they were exceptional!!

Melissa M.

Kennebunk

This team of individuals was professional at all times. They set up barriers that kept the dust at a minimum. They conducted an air flow audit and cut the draft circulation from the outside in half by sealing cracks. They hauled out the old insulation and replaced it with blown in insulation with an R - 60 Value. They also did the rebate paperwork so that I could get my $1500.00 rebate from the state of Maine. I highly recommend Evergreen Home Performance!

Daniel B.

Rockland

Very Satisfied with the work performed by Evergreen. Professional employees, high quality work done in a timely manner. My sales rep was Justin, and he was phenomenal During the initial walk around my house, he gave me great ideas for how to improve the efficiency of our home. We will consult with Evergreen for our future home projects.

Adam G.

Westbrook

Bryan, Dave and the entire Evergreen team are wonderfully professional, prompt and thorough. I enjoyed working with them and look forward to continued work as we upgrade our home! Thank you so much for your professionalism, fairness, time and diligence.

Cait

Yarmouth

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