Which Insulation Type Qualifies for Mass Save® Rebates? A Guide for Massachusetts Homeowners

 

Why Insulation Type and Location Both Matter

If you’ve ever searched “best insulation for my home” and walked away more confused than when you started, you’re not alone. The right answer depends on two things working together: the material you choose and where in your home you’re installing it. It also depends on what Massachusetts’s Mass Save® program will actually cover — because not every insulation type qualifies for rebates. This guide walks you through exactly what you need to know, so you can make smart decisions before spending a dime.

 

The Main Insulation Materials

 

Cellulose

Made from 75–83% recycled paper and treated with borate (a naturally occurring mineral) for fire, mold, and pest resistance, cellulose is one of the most eco-friendly and effective options available. It can be dense-packed into existing wall cavities or blown loosely into attic spaces. It is Mass Save® eligible.

 

Fiberglass

Available in batt form or blown-in, fiberglass is one of the most widely used insulation materials in the country. Blown-in fiberglass is particularly effective in attics and netted wall cavities, offering flexible R-values and strong performance in New England’s cold winters. It is Mass Save® eligible.

 

Mineral Wool (Rockwool)

Made from molten rock or furnace slag, mineral wool handles high temperatures well and provides excellent sound absorption. It comes in batt, board, and blown-in forms and is suitable for both interior and exterior applications. It is Mass Save® eligible.

 

Spray Foam

Open-cell spray foam delivers around R-4.2 per inch, while closed-cell reaches R-7 or more per inch — making it one of the highest-performing options, especially in tight spaces. Although Mass Save® doesn’t cover spray foam insulation upgrades, it is a great option to consider for improving your home’s energy efficiency.

 

Insulation by Location — What Mass Save® Covers

 

Attic Insulation

The attic is typically where Massachusetts homes lose the most heat. Blown-in cellulose and blown-in fiberglass are the go-to materials for open attic floors, delivering strong R-values at an affordable cost. Before any insulation goes in, air sealing is essential — gaps around chimneys, plumbing chases, recessed lights, and dropped soffits allow conditioned air to escape and must be addressed first. The good news: no-cost air sealing is included in Revise, Inc.’s Mass Save® Home Energy Assessment. Attic insulation upgrades are among the most commonly recommended improvements and are eligible for rebates of up to 75–100%.

 

Wall Insulation

Older Massachusetts homes often have wall cavities that are completely empty or filled with degraded material. Dense-packed cellulose and blown-in fiberglass are ideal here because they can be injected through small drilled holes — no major renovation required. For open walls during a gut renovation, mineral wool batts are an excellent option. Wall insulation is eligible for Mass Save® rebates when recommended by a Revise, Inc. Home Energy Manager.

 

Basement and Rim Joist Insulation

An uninsulated basement is one of the most common causes of cold floors and high heating expenses in Massachusetts homes. The rim joist — the framing that sits on top of your foundation — is a particularly significant air leakage point. Rigid board, fiberglass batts, and mineral wool all perform well in basements, and rim joist air sealing is included at no cost through the Mass Save® program. Since basements are often treated as semi-conditioned spaces, the exact scope of work is determined during your assessment.

 

Crawlspace Insulation

Crawlspaces require careful attention to moisture before any insulation is installed. In a vented crawlspace, insulating the floor above with fiberglass batts or mineral wool is the standard approach. In an unvented crawlspace, insulating the foundation walls is more effective. Either way, a blower door test before and after the work confirms that the air sealing is performing as it should. Mass Save® covers eligible crawlspace insulation upgrades.

 

Knee Walls and Buffer Zones

Cape-style and colonial homes throughout Massachusetts commonly have knee walls — short vertical walls that separate living space from unconditioned attic space behind sloped ceilings. These are notorious for air leakage. Blown-in cellulose or fiberglass combined with rigid air barriers works well here, and the air sealing at knee wall floors and tops is covered at no cost through Mass Save®.

 

What’s Included in a No-Cost Home Energy Assessment

Revise, Inc. offers Mass Save® No-Cost Home Energy Assessments for Massachusetts homeowners. During the visit, a certified Revise, Inc. Home Energy Manager evaluates your home’s current insulation levels, identifies air leakage pathways, and provides a customized report outlining your highest-priority upgrades. Air leaks are sealed on the spot at no charge. From there, eligible insulation improvements are covered at 75–100% off, up to $2,000, with 0% financing available for qualifying improvements. Generous rebates on high-efficiency heating, cooling, and water heating equipment round out the program.

The assessment removes the guesswork entirely. You don’t need to figure out which material or which location — your Revise, Inc. Home Energy Manager does that for you.

 

Frequently Asked Questions:

 

1)  What types of insulation does Mass Save® cover in Massachusetts? 

Mass Save® covers cellulose, fiberglass (batt and blown-in), and mineral wool in eligible locations, including attics, walls, basements, crawlspaces, and knee walls. Coverage is determined by a Mass Save® No-Cost Home Energy Assessment conducted by Revise, Inc.

 

2)  Does Mass Save® cover spray foam insulation? 

Although Mass Save® doesn’t cover spray foam insulation upgrades, it is a great option to consider for improving your home’s energy efficiency. A Home Energy Assessment can help you understand where spray foam might complement Mass Save®-eligible work.

 

3)  How much can I save on insulation through Mass Save®? 

Eligible Massachusetts homeowners can receive up to 75–100% off insulation improvements, up to $2,000. Zero-percent financing is also available for qualifying upgrades.

 

4)  What is the best insulation for an attic in Massachusetts? 

Blown-in cellulose and blown-in fiberglass are the most widely recommended materials for attic floors in Massachusetts, offering strong R-values and Mass Save® eligibility. Air sealing must be completed first.

 

5)  Can I get Mass Save® rebates for wall insulation in an existing home? 

Yes. Dense-packed cellulose and blown-in fiberglass are ideal for existing wall cavities via a drill-and-fill method and are eligible for rebates when recommended following a Home Energy Assessment.

 

6)  What is a blower door test, and why is it part of the process? 

A blower door test depressurizes your home to measure air leakage and identify exactly where air is escaping. Mass Save® contractors use it to confirm that air sealing is working effectively before and after insulation is installed.

 

7)  What insulation is recommended for a Massachusetts basement or rim joist? 

Rigid board, fiberglass batts, and mineral wool are all effective for basement and rim joist insulation. Rim joist air sealing is included at no cost through the Mass Save® program.

 

8)  What happens during a No-Cost Mass Save® Home Energy Assessment? 

A certified Revise, Inc. Home Energy Manager evaluates your home’s insulation, identifies air leaks, seals them on the spot at no charge, and provides a customized report outlining rebate-eligible improvement recommendations.

 

9)  Is cellulose insulation safe? 

Yes. Cellulose is made from recycled paper and treated with borate, a naturally occurring mineral that provides fire, mold, and pest resistance. It contains no harmful fibers and is widely considered one of the healthier insulation options for occupied homes.

 

10)  How do I know which insulation upgrade will give me the best return? 

A Mass Save® No-Cost Home Energy Assessment conducted by Revise, Inc. is the most reliable way to find out. Your Revise, Inc. Home Energy Manager evaluates your home’s specific construction, existing insulation levels, and climate exposure to prioritize the upgrades with the greatest energy savings and rebate potential.

 

Schedule Your No-Cost Home Energy Assessment Today

Ready to find out exactly what your home needs — and what Mass Save® will pay for? Revise, Inc. makes it simple. Visit callrevise.com to schedule your Mass Save® No-Cost Home Energy Assessment conducted by Revise, Inc. and start accessing the rebates you’re entitled to.

Some restrictions apply and offers are subject to change or cancellation. Visit MassSave.com/HEA for full details.

 

 

Also Read: 

Maximize Your Energy Savings with Mass Save Insulation in Woburn

Everything You Need to Know About Heat Pump Rebates in Woburn

How to Lower Your Gas Bill in Woburn Without Sacrificing Comfort