insulation
H = healthy
Is the material safe?
D = durable
Will the material last?
C = conscious
Is the material sustainable?
Materials we actively promote.
Materials we like to use.
Materials we use.
Materials we try to avoid.
Materials we advocate against.
batt & blanket
Batt insulation are pre-cut, flexible panels designed to fit between standard studs, joists, and other framing. They are commonly used in walls, attics, floors and in sound insulation applications. Batt insulation is relatively easy to install and remove or adapt later and is available in a variety of materials and thicknesses.
Blanket insulation is similar to batt insulation manufactured in larger rolls before they have been cut down to standard widths. Blankets are great for applications where continuous non-rigid insulation is required.
wood fiber batt
H — Plant-based, non-toxic, healthy, borates used as a flame retardant and to inhibit mold, mildew, and deter insects, non-irritating fibers, installed with minimal protective equipment, no dangerous off-gassing.
C — Use of carbon sequestering wood pulp, fully recyclable, carbon-negative depending on manufacturer and transport distance, domestic production now available.
D — Reduces air infiltration while being vapor-open, moisture-resistant, high heat capacity and low thermal conductivity, great acoustic insulative properties.
hemp wool batt
H — Plant-based, non-toxic, healthy, naturally resistant to mold, bacteria, and fungi, high acoustic attenuation, installs with minimal protective equipment.
C — Natural fiber, grows quickly, uses minimal land and water resources, carbon sequestering, carbon-negative depending on manufacturer and transport distance, can be sourced locally.
D — Moisture-resistant, maintains thermal properties when wet, vapor-open, fire-resistant, comparable R-value to fiberglass batts.
sheep wool batt / blanket
H — Natural, non-toxic, healthy, 100% sheep's wool, available without synthetic contaminants or additives, regulates indoor humidity, resistant to mold and mildew, purifies air and breaks down organic compounds, installs with minimal protective equipment.
C — Concerns around GHG emissions, water usage, and land degradation from livestock, animal welfare considerations depending on farming practices, completely biodegradable, usually sourced from overseas.
D — Hygroscopic, maintains insulative properties when wet, can withstand repeated wetting cycles, naturally fire-resistant, will not maintain a flame, pest-resistant, lower R-value per inch than loose-fill, polymer binders used for products with increased loft.
cotton batt
H — Natural, non-toxic, typically contains no irritating chemical additives, boric acid may be added as insect repellant and fire retardant, safe and DIY-friendly installation.
C — Cotton cultivation has negative ecological impacts from water and fertilizer usage, batts are mostly made from offcut waste from garment industry.
D — Not resistant to wetting or mold, must be kept dry, highly flammable if not treated with boric acid.
mineral wool batt
H — Skin and lung irritant during installation, may contain off-gassing phenol-formaldehyde or heavy metals from the blast furnace slag.
C — Manufacturing process is very energy-intensive, highest GHG footprint of common insulations besides spray foam.
D — Does not degrade from moisture exposure, can withstand repeated wetting cycles, fire-resistant, pest and rodent-resistant, extremely long-lasting.
fiberglass batt
H — Fibers can irritate skin, throat, and nasal passageways, and can be suspended in air, may contain off-gassing phenol-formaldehyde, flame retardants, or asphalt-based binders with hydrocarbon impurities.
C — Not reusable or biodegradable, contains high recycled fiber content, lower GHG emissions than mineral wool or rigid foam, or spray foam.
D — Moisture exposure can permanently lower the insulation value and lead to mold growth, long-lasting if kept dry, resistant to insect damage, common and easy to install.
loose-filled & spray-applied
Loose-fill insulation also called blown-in insulation, is made up of small particles or fibers of an insulating material installed by pouring, stuffing, or blowing the loose material into cavities and spaces. Loose-fill insulation is especially useful for insulating hard-to-reach, non-standard, or irregular spaces where batt insulation installation becomes impractical.
Spray-applied insulation is a liquid mixture that expands and solidifies into a foam, providing an airtight and seamless insulation layer. Spray-applied insulation is often used in areas with irregular shapes and in locations where a high R-value or continuous air control layer around a complex shape is needed.
light-straw clay (LSC)
H — Plant-based, natural, non-toxic, does not off-gas, regulates indoor humidity, mold-resistant, the clay coating protects the straw, can last hundreds of years.
C — Locally sourced, inexpensive, readily available, lightweight, completely renewable and biodegradable, carbon-sequestering, low GHG impact from sourcing and transport.
D — Hygroscopic, low R-value per inch, labor-intensive process to make and install, low-tech, safe, suitable for DIY projects, fire resistant.
blown-in wood fiber
H — Plant-based, non-toxic, some products contain petroleum-based wax binder, does not promote mold or bacteria growth, non-irritating fibers.
C — Recyclable, biodegradable, carbon negative, fills entire cavity and reduces air leakage, sustainable when sourced from well-managed forests, often sourced from overseas.
D — Vapor-open, moisture buffering, hygroscopic and manages moisture in the wall assembly, fire-resistant, good acoustic insulator.
loose-fill sheep wool
H — Natural, non-toxic, 100% sheep wool, no synthetic contaminants or additives, regulates indoor humidity, resistant to mold, and mildew, purifies air, and breaks down organic compounds, installs with minimal protective equipment.
C — Concerns around GHG emissions, water usage, land degradation and animal welfare considerations dependant on farming practices, completely biodegradable, often sourced from overseas.
D — Hygroscopic, maintains insulative properties when wet, can withstand repeated wetting cycles, naturally fire-resistant, will not maintain a flame, pest-resistant, higher R-value per inch than batt / blanket.
blown-in / dense-pack cellulose (dry)
H — Natural base product, does not off-gas VOCs, treated with non-toxic boric acid for fire and pest resistance, generates dust during installation process which requires protective equipment.
C — Easy to install, inexpensive, less energy-intensive to produce than fiberglass, can be made from products with a high-recycled content, biodegradable.
D — Risk of settling over time reducing effective R-value and creating variable conditions within the wall assembly, susceptible to mold growth if it gets wet, limited ability to reduce reduce air leakage.
blown-in fiberglass
H — Fibers can irritate skin, throat, and nasal passageways, and can become suspended in air, may contain off-gassing phenol-formaldehyde, flame retardants, or asphalt-based binders with hydrocarbon impurities.
C — Not reusable or biodegradable, contains high recycled content, lower GHG emissions than mineral wool, rigid foam, or spray foam.
D — Moisture exposure can permanently lower the insulation value and lead to mold growth, long-lasting if kept dry, resistant to insect damage, common and easy to install.
spray-applied cellulose (wet)
H — Natural base product, may contain chlorinated flame retardants, high mold concerns when adding a high-moisture product within light-frame wood construction.
C — Addition of toxic chemicals negates relative eco-friendliness of cellulose, high recycled content.
D — Significant moisture concerns due to extended saturation of structural members during curing process, long drying time before enclosing, high reduction to air leakage, not an effective air barrier.
open cell spray foam (ocSPF)
H — Significant off-gassing of highly toxic chemicals, installers must wear full PPE, foams continue to off-gas and pose health risks after curing, not appropriate for a healthy home.
C — High GHG emissions from manufacture, blowing, and installation, soy-based blowing agents not available, not biodegradable or recyclable, not appropriate for a conscious home.
D — High R-value, high expansions allows insulation of tight spaces, not fully vapor-closed like ccSPF, difficult to remove once installed, requires qualified installer, acts as air barrier, does not facilitate drying, can ignite.
closed cell spray foam (ccSPF)
H — Significant off-gassing of highly toxic chemicals, installers must wear full PPE, foams continue to off-gas and pose health risks after curing, not appropriate for a healthy home.
C — Very high GHG emissions from manufacture, blowing, and installation, not biodegradable or recyclable, not appropriate for a conscious home.
D — Very high R-value, difficult to remove once installed, requires qualified installer, acts as air barrier, fully vapor-closed, does not facilitate drying, combustible, can ignite.
rigid & board
Rigid insulation also called board insulation, is available in foam and natural fiber options formed into rigid boards which provide a continuous insulation layer. They are commonly used on exterior walls, roofs, and foundations. Rigid insulation offer good thermal resistance and can allow or prevent vapor diffusion depending on the material and installation method.
wood fiberboard
H — Plant-based, natural, non-toxic, contains small amount of paraffin wax, mold-resistant, good acoustic insulator, installs with minimal protective equipment.
C — Renewable product from recycled post-industrial and recycled wood chips, carbon sequestering, usually sourced from overseas.
D — Waterproof and vapor-open, maintains insulative properties when wet, excellent thermal insulator, dimensionally stable, resistant to compression.
hemp fiberboard
H — Plant-based, non-toxic, naturally resistant to mold, bacteria, and fungi, high acoustic attenuation, installs with minimal protective equipment.
C — Natural fiber, grows quickly, uses minimal land and water resources, carbon sequestering, can be carbon-negative depending on manufacturer and transport distance, can be sourced locally.
D — Moisture-resistant, maintains thermal properties when wet, vapor-open, fire-resistant, comparable in R-value to fiberglass batts.
cork fiberboard
H — Plant-based, natural, non-toxic, no chemical additives, mold resistant, good acoustic insulator, installs with minimal protective equipment.
C — Naturally renewable product, fast-growing, carbon sequestering, fully biodegradable and recyclable at end of life, usually sourced from overseas.
D — Waterproof and vapor-open, hygroscopic, maintains insulative properties when wet, excellent thermal insulator, can be used as cladding, dimensionally stable, resistant to compression.
mineral wool fiberboard
H — Fibers can be a skin and lunch irritant during installation, good acoustic insulator, important to choose products not bound with off-gassing phenol-formaldehyde.
C — Manufacturing process is very energy-intensive, high GHG emissions during production.
D — Naturally flame and pest-resistant, doesn't degrade from moisture exposure, extremely long-lasting, can be used below grade.
fiberglass board
H — Glass fibers and a binder, may contain halogenated flame retardants, phenol-formaldehyde, does not promote the growth of mold, fungi or bacteria, lightweight, easy to handle.
C — Energy-intensive production and a high embodied energy product, may contain a high percentage of recycled glass, not biodegradable or readily recyclable.
D — Versatile product, high thermal and acoustic sound absorber, faced products can be fire-resistant.
polyisocyanurate (ISO) foamboard
H — Off-gassing introduces health risks to occupants of home, toxic manufacturing process, not appropriate for use on the interior of a healthy home.
C — Petroleum-derived product, blowing agent has lowest GWP of any foam, not biodegradable or readily recyclable.
D — High R-value, steadily loses insulative properties in cold temperatures, vapor closed, does not facilitate drying.
expanded polystyrene (EPS) foamboard
H — Often treated with toxic flame retardants, product itself is relatively inert once formed, manufacturing exposes workers to some health hazards, not appropriate for use on the interior of a healthy home.
C — Petroleum-derived product, but EPS is 98% air and uses relatively little material, blowing agent for foam has relatively low GW, not biodegradable or readily recyclable.
D — Relatively high R-value, vapor closed, easy to work with, common, risk of water damage to structure and finishes, dimensionally stable, can be used below grade.
graphite polystyrene (GPS) foamboard
H — Does not use hydrofluorocarbon (HFC) blowing agents like XPS, manufacturing process similar to EPS, not appropriate for use on the interior of a healthy home.
C — Petroleum-derived product, blowing agent has extremely high GWP, not biodegradable or readily recyclable, can be produced with post-industrial or post-consumer recycled content.
D — Graphite particles that are infused into the polystyrene beads, reflect and absorb radiant energy, higher R-Value than standard EPS, durbale, long lasting.
extruded polystyrene (XPS) foamboard
H — Off-gassing introduces health risks to occupants of home, toxic manufacture process, not appropriate for use on the interior of a healthy home.
C — Petroleum-derived product, blowing agent has extremely high GWP, not biodegradable or readily recyclable, not appropriate for a conscious home.
D — High initial R-value per inch, loses insulative properties over time due to off-gassing, high compressive strength, vapor impermeable and can contribute to moisture issues.
block & aggregate
Block insulation refers to insulation materials that come in the form of rigid, rectangular blocks or panels. These blocks are made from various insulating materials and are used to provide a continuous layer of insulation commonly used for exterior walls and foundations.
Aggregate insulation consists of loose, granular insulating materials resemble non-insulating gravel used as an alternative to rigid insulation in sub-slab applications or around footings and stem walls. Aggregate insulation has the added benefit of providing a capillary break when used below slabs or footings.
straw bale
H — Plant-based, natural, healthy, no VOCs, supports positive IAQ, regulates indoor humidity, low-tech installation with limited protective equipment.
C — Inexpensive, readily available, and renewable, low GHG impact from sourcing and transport, 100% biodegradable at end of life cycle, can be sourced locally.
D — Lasts decades if properly maintained, thick assembly required, susceptible to moisture damage from infiltration from damaged exterior cladding.
hemp block
H — Plant-based, natural, healthy, no VOCs, mold resistant, vapor-permeable, supports positive IAQ, regulates indoor humidity, typically produced without toxic chemical additives, often contains polyester binder.
C — Carbon negative, requires reinforced concrete post & beam structure with a high ECC due to concrete and steel manufacture process.
D — Extremely durable, hygroscopic, water and moisture resistant, excellent acoustic performance, fire resistant, pest and termite resistant.
wood insulated concrete forms (WICF)
H — No VOCs, mold resistant, vapor-permeable, supports positive IAQ, regulates indoor humidity, can be produced without toxic chemical additives.
C — Made with recycled wood pallets, requires reinforced concrete post & beam structure with a high ECC due to concrete and steel manufacture process, can be sourced locally.
D — Extremely durable, can last hundreds of years, can be used below grade, alternative to poured concrete, fire and pest-resistant, excellent thermal and sound insulation, won't lose insulative value over time.
foam glass gravel
H — Chemically inert, and non-toxic, used in sub-slab assemblies, acts and insulation and drainage layer, alternative to rigid foam.
C — Recycled product, manufacture process has high embodied energy, finished product is roughly 90% air, few manufacturers, and may be shipped large distances.
D — Extremely durable, won't lose insulative value over time, lightweight, easy to install, structurally load-bearing, water resistant, fireproof, pestproof, rot proof, frost heave resistant.
lightweight expanded clay aggregate (LECA)
H — 100% inert, contains no harmful substances or gases, non-irritating, requires no special equipment or protective equipment to handle.
C — Energy-intensive firing process, comparable to brick or ceramic, made from natural clay, sustainable and ethical with good mining practices, usually sourced from overseas.
D — Extremely durable, excellent thermal and acoustical insulation, absorbs water, dimensionally stable, and has good drainage, fire, earthquake, and pest-resistant.
perlite
H — Chemically inert and non-toxic, dust generation presents concerns during installation.
C — Manufacturing process is energy intensive and mining environmentally destructive.
D — Noncombustible, repels pests, does not settle under its own weight, low R-value per inch, extremely long lifespan.
autoclaved aerated concrete (AAC)
H — May contain fly ash which is a byproduct of coal production, good acoustic insulator, lightweight.
C — Precast concrete product, energy-intensive autoclaving process, expansion agent rises mixture, similar to yeast in bread dough, recyclable.
D — Lightweight, low insulation value compared to other block systems, lower structural strength to other concrete products, water, fire, pest and rodent resistant, low water absorption.
foam insulated concrete forms (FICF)
H — Lacks vapor permeability of WICFs, does not contribute to positive IAQ, does not regulate indoor humidity.
C — Petroleum-derived product, reinforced concrete has a high ECC due to concrete and steel manufacture process.
D — Durable, moisture, can be used below grade, good thermal and sound insulator, susceptible to fire and pest damage.