If you’ve got rooms that are always colder – or hotter – than the rest of the house, chances are your walls are under-insulated. It’s a common issue we see in many older Maine homes and a primary cause of discomfort for homeowners who have switched to heat pumps for heating and cooling.
From historic capes to coastal farmhouses, Evergreen provides wall insulation services in Portland, Maine and the surrounding areas of Southern and Coastal Maine, helping you improve comfort and energy efficiency – without compromising your home’s character or structure.
- Eligible for up to $8,000 in Efficiency Maine rebates
- Over 4,500 Maine homes improved since 2006
- BPI-certified experts using building science-backed solutions


How We Insulate Existing Walls – Carefully and Effectively
We know that preserving your home’s character is important. Many of our customers live in historic Maine homes with original plaster, woodwork, or shingle siding that they want to protect.
Wall insulation can make a big impact on your comfort and energy efficiency—but it’s also one of the more complex upgrades we do. Think of it like minor surgery for your home’s envelope. It requires the right tools, techniques, and safety protocols, including lead-safe work practices.
That’s exactly why you want a team that knows how to do this work carefully, respectfully, and completely—without cutting corners.
What’s the Best Type of Attic Insulation?
We offer a range of attic insulation materials to match your home’s needs, but in most Maine homes, we recommend:
Step 1: Precision Drilling
We make small, precise 2.5-3” access holes—either inside (often behind baseboards or in closets) or on the exterior (behind siding or shingles). These openings are just large enough to install insulation but small enough to repair neatly.
Step 2: Dense-Pack Cellulose Installation
Before we install insulation, we seal leaks with spray foam to prevent air infiltration. This critical step protects against drafts that can weaken your insulation’s effectiveness and ensures your insulation performs as designed.
Step 3: Careful Restoration
Once the insulation is installed, we patch and restore each access point, including replacing siding on exterior walls. For both exterior and interior jobs, we leave the areas caulked, primed, and paint-ready. Meanwhile, your home will be more comfortable and energy-efficient!
Wall insulation is well worth doing for comfort and efficiency and to maximize the impact of heat pumps. However much of the cost comes from restoring finished surfaces, which makes this project best coupled with other renovations if possible.
Some Victorian-era Maine homes have balloon framing, which can allow us to insulate some or all of your walls from the attic much more easily. Every home is different, and we’ll help you understand your options during your free consult.

The Benefits of Blown-In Wall Insulation
- More consistent comfort from room to room (especially in homes that have switched to heat pumps)
- Warmer in winter, cooler in summer
- Quieter rooms and reduced outside noise
- Fewer indoor drafts and temperature swings
- Lower heating and cooling bills


Affordable Home Upgrades with Efficiency Maine Insulation Rebates
Insulating your walls is a smart investment—and it’s made easier by Efficiency Maine rebates and other incentives. When you upgrade your home’s exterior wall insulation, you can qualify for:
- Up to $8,000 in Efficiency Maine rebates
- Loan payments as low as $50/month through Efficiency Maine & NEIF financing
- An additional 30% federal tax credit (up to $1,200 for insulation and air sealing)
Why Choose Evergreen Home Performance?
- More than 4,500 Maine homes improved since 2006
- Experts in historic and hard-to-insulate homes
- BPI-certified professionals using the latest building science
- 15,000+ home energy audits completed
- More Mainers received Efficiency Maine insulation rebates with us than any other company in 2024


Book a Free Consult Today to Get Started
Whether your walls are drafty, your rooms are uneven in temperature, or you just want a quieter, healthier, more energy-efficient home, Evergreen is here to help.
We start every project with a free consult, and then move to a professional home energy audit to pinpoint exactly where your home is losing energy—and how to fix it.