Insulation Materials and Applications

Cozy Home Performance offers a range of insulation options to address the variety of target R-values, thermal boundaries and budgets. Different insulation materials offer different thermal qualities. Not only will the R-value per inch differ between products, some materials are air and/or vapor barriers and some offer good acoustical performance and fire resistance.

Cozy Home Performance is happy to work with you to meet your goals and offer clear information on the many different insulation materials and which ones will best work for your project.


Cellulose is one of the most common insulation materials. It is made of recycled news paper and treated with Borate to provide excellent fire resistance. Cellulose can be used in a variety of applications. It’s R-vlaue is 3.5 per inch, and can be installed loose in an attic flat over existing insulation or in a new construction application.


Cellulose in an attic flat

attic_cellulose_insulation_western ma_airsealing

Cellulose being blown into attic flat

Cellulose can also be dense-packed into an exterior wall cavity and offers excellent acoustic qualities.  In a new construction application the wall cavities are netted and then the cellulose is blown into the cavity under high air pressure to prevent settling. For installation in finished houses, the siding is removed, holes are drilled and the insulation is blown into the cavity from the exterior.


New Construction, netted wall dense packed

cellulose_insulation_exterior wall_drill and fill

Exterior wall being insulated with cellulose







Rigid Board Insulation

Polyisocyanurate (polyiso) rigid board insulation has a R-value of 6.5 per inch. It has a foil face and comes in 4’x8′ sheets and a variety of thicknesses from 1/2″ to 2″ thick. Two of the main application that Cozy Home Performance installs this insulation is in basement sill bands and in knee walls.

With it’s high R-value and being an air/vapor barrier, when a 2″ piece (R-13) is installed and air sealed into a sill band it will help insulate basements from exterior temperatures. Polyiso is a far better choice for insulating a sill band than the commonly used fiberglass.

basement_sillband_insulation_air-seal_rigid board_polyiso

Basement Sill Band insulated with 2″ Polyiso and air-sealed

Polyiso is also a good choice when your home has a kneeewall that needs to be insulated. Installing polyiso over the face of the rafters and having the rafter bays filled with either cellulose or fiberglass, makes an air-tight assembly that creates a thermal break over the wood rafters and stabilizes the temperature in the kneewall and makes a clean storage area.

kneewall_instulation_rigid board_poyiso

Kneewall rafters insulated with Polyiso board


Closed Cell Spray Foam

Closed cell spray foam, also know as Spray Polyurethane Foam (SPF), is better than any other type of insulation at reducing air leakage, and has a R-value of 6.5 per inch. SPF is a two component foam that mix at the point of installation, expands and harden within seconds of application, creating an air-tight, high R-value seal that is also a vapor retarder.

Cozy Home Performance has worked with SPF for many years. Our sister company, FoamUSA, is equipped to handle large new construction and commercial applications.

new construction-spray foam-insulation-attic

New Construction, entire room installed with closed cell spray foam

spray foam_new construction_rafters_insulation_attic

New Construction, rafter bays being spray foamed with closed cell

Closed cell spray foam is not only used in large applications, it is also used in smaller spot applications, by way of a portable kit, to provide a high R-value and air-tight thermal barrier. Areas such as sill bands and soffits are common areas where SPF is installed in retrofit applications. SPF in a basement sill-band and over the above grade foundation wall prevent outside temperatures and air leakage from entering your home and stabilize your basement temperature which will effect your entire home. Installing closed cell spray foam into the soffit area in an attic, seals the exterior wall top plate, allows a high R-value to be reached in a limited space and helps prevent the build up of ice damming in the eaves.

basement-sillband-closed cell-spray foam-insulation-top plate-air seal

Basement sill band insulated and air sealed with closed cell spray foam

attic-air seal-closed cell-spray foam-retro fit-insulation

Attic soffit insulation and air sealing with closed cell spray foam, retrofit

new construction-insulation-attic-air seal-closed cell-spray foam

New Construction, attic soffit insulated and air sealed with closed cell spray foam



Fiberglass is a insulation material that is most common in older homes. It comes in loose and batt forms. It’s R-value is approx. 3.5 per inch. Because we have seen the effect time has on fiberglass, Cozy Home Performance does not normally install fiberglass unless the client requests it. Fiberglass is very porous and allows air to easily pass through it’s fibers, which traps dirt and dust over time causing it to turn black in areas. Also, because of it’s porous nature, if it is exposed to outside temperatures, like in attics, the hot and cold air penetrates it’s fibers and diminishes it’s R-value. If it is installed properly in a contained bay, then fiberglass does perform as intended.

attic-fiberglass-air sealing-insulation

Fiberglass showing how it traps dirt and dust particles from air passing through it’s fibers

A common installation of fiberglass is in the ceiling of a crawlspace. Cozy Home Performance has seen many basements and crawlspaces that have had fiberglass installed in the ceiling and how it falls from the bays and how mice easily access these areas and make there homes in the fiberglass. A solution to these problems is to cover the fiberglass with 2″ of Polyiso rigid insulation board. This contains the fiberglass and prevents air leakage and easy access for mice.


crawlspace-basement-insulation-fiberglass-rigid board

A crawlspace that has been insulated with fiberglass and then covered with 2″ polyiso rigid insulation


As you can see there are a number of insulation options, each having its own quality and application. Cozy Home Performance can evaluate your homes needs and thermal boundary weak areas and provide you with the best products and installation.






Testimonials from Cozy Home Customers

Browse more testimonials →

Cozy Home Performance is hands down the best energy diagnostic and insulation company in the Valley. Mark and his crew enter and exit your work stream seamlessly, on time and on budget. The key is the knowledge, experience and personal responsibility each employee brings to his work. Mark not only has design experience, he also has the creative spark that leads to innovative solutions to unique problems. With all forms of insulation under one roof, careful diagnostics and appropriate choice of material, one always get the most out of every insulation dollar from Cozy Home Performance!!
John Ferriter, in construction in the Valley for 45 years
I’m happy that the incentive was more than anticipated (As a Home Performance Contractor with Mass Save Cozy Home secured $2,760 in project incentive funds.). I enjoyed working with you and your crew. Everyone was pleasant to deal with. They were professional and courteous and when I had questions, the answers were in a non-technical response so I could understand. Each day they left the area clean.
D.N., Easthampton, MA
Someone from the utility company was here today to inspect the work resulting from their incentive. They were very positive both about the quality of the recommendation, and the quality of the work. I am pleased too. I’m almost looking forward to next winter to see the difference.
Phil, Northampton, MA
The house definitely feels different – hard to explain the feeling, maybe more solid? Anyway, we have checked out all the work areas that we could and are really impressed. We can already feel the difference in some rooms – even with the warmer weather! Thanks to all the guys who were at the house. They were all very polite and pleasant and seem to have done an awesome job!
K.C., Goshen, MA