Building insulation material


Building insulation materials are the building materials that form the thermal envelope of a building or otherwise reduce heat transfer.
Insulation may be categorized by its composition, form, structural contribution, functional mode, resistance to heat transfer, environmental impacts, and more. Sometimes a thermally reflective surface called a radiant barrier is added to a material to reduce the transfer of heat through radiation as well as conduction. The choice of which material or combination of materials is used depends on a wide variety of factors. Some insulation materials have health risks, some so significant the materials are no longer allowed to be used but remain in use in some older buildings such as asbestos fibers and urea.

Consideration of materials used

Factors affecting the type and amount of insulation to use in a building include:
  • Thermal conductivity
  • Moisture sensitivity
  • Compressive strength
  • Ease of installation
  • Durability – resistance to degradation from compression, moisture, decomposition, etc.
  • Ease of replacement at end of life
  • Cost effectiveness
  • Toxicity
  • Flammability
  • Environmental impact and sustainability
Considerations regarding building and climate:
  • The average climate conditions in the geographical area the building is located
  • The temperature the building is used at
Often a combination of materials is used to achieve an optimum solution and there are products which combine different types of insulation into a single form.

Spray foam

Spray foam is a type of insulation that is sprayed in place through a gun. Polyurethane and isocyanate foams are applied as a two-component mixture that comes together at the tip of a gun, and forms an expanding foam. Cementitious foam is applied in a similar manner but does not expand. Spray foam insulation is sprayed onto concrete slabs, into wall cavities of an unfinished wall, against the interior side of sheathing, or through holes drilled in sheathing or drywall into the wall cavity of a finished wall.

Advantages

  • Blocks airflow by expanding & sealing off leaks, gaps and penetrations.
  • Can serve as a semi-permeable vapor barrier with a better permeability rating than plastic sheeting vapor barriers and consequently reduce the buildup of moisture, which can cause mold growth.
  • Can fill wall cavities in finished walls without tearing the walls apart.
  • Works well in tight spaces.
  • Provides acoustical insulation.
  • Expands while curing, filling bypasses, and providing excellent resistance to air infiltration.
  • Increases structural stability.
  • Can be used in places where loose-fill cannot, such as between joists and rafters. When used between rafters, the spray foam can cover up the nails protruding from the underside of the sheathing, protecting your head.
  • Can be applied in small quantities.
  • Cementitious foam is fireproof.

    Disadvantages

  • The cost can be high compared to traditional insulation.
  • Most foams, with the exception of cementitious foams, release toxic fumes when they burn.
  • According to the US Environmental Protection Agency, there is insufficient data to accurately assess the potential for exposures to the toxic and environmentally harmful isocyanates which constitute 50% of the foam material.
  • Depending on usage and building codes and environment, most foams require protection with a thermal barrier such as drywall on the interior of a house. For example, a 15-minute fire rating may be required.
  • Can shrink slightly while curing if not applied on a substrate heated to the manufacturer's recommended temperature.
  • Although CFCs are no longer used, some use HCFCs or HFCs as blowing agents. Both are potent greenhouse gases, and HCFCs have some ozone depletion potential.
  • Many foam insulations are made from petrochemicals and may be a concern for those seeking to reduce the use of fossil fuels and oil. However, some foams are becoming available that are made from renewable or recycled sources.
  • R-value will diminish slightly with age, though the degradation of R-value stops once an equilibrium with the environment is reached. Even after this process, the stabilized R-value is very high.
  • Most foams require protection from sunlight and solvents.
  • It is difficult to retrofit some foams to an existing building structure because of the chemicals and processes involved.
  • If one does not wear a protective mask or goggles, it is possible to temporarily impair one's vision..
  • May require the HVAC system to have a source of fresh outside air, since the structure may not refresh inside air without it.

    Advantages of closed-cell over open-cell foams

  • Open-cell foam is porous, allowing water vapor and liquid water to penetrate the insulation. Closed-cell foam is non-porous, and not moisture-penetrable, thereby effectively forming a semi-permeable vapor barrier.
  • Closed-cell foams are superior insulators. While open-cell foams typically have R-values of 3 to 4 per inch, closed-cell foams can attain R-values of 5 to 8 per inch. This is important if space is limited, because it allows a thinner layer of insulation to be used. For example, a 1-inch layer of closed-cell foam provides about the same insulation factor as 2 inches of open-cell foam.
  • Closed-cell foam is very strong, and structurally reinforces the insulated surface. By contrast, open-cell foam is soft when cured, with little structural strength.
  • Open-cell foam requires trimming after installation, and disposal of the waste material. Unlike open-cell foam, closed-cell foam rarely requires any trimming, with little or no waste.

    Advantages of open-cell over closed-cell foams

  • Open cell foams will allow timber to breathe.
  • Open cell foams are incredibly effective as a sound barrier, having about twice the sound resistance in normal frequency ranges as closed-cell foam.
  • Open cell foams provide a better economical yield.
  • Open cell foams often have a low exothermic reaction temperature; will not harm coatings on electrical wiring, plumbing or other building components.

    Types

;Cementitious foam: One example is AirKrete, at R-3.9 per inch and no restriction on depth of application. Non-hazardous. Being fireproof, it will not smoke at all upon direct contact with flame, and is a two-hour firewall at a application, per ASTM E-814 testing. Great for sound deadening; does not echo like other foams. Environmentally friendly. Non-expansive. Fully sustainable: Consists of magnesium oxide cement and air, which is made from magnesium oxide extracted from seawater. Blown with air. Nontoxic, even during application. Does not shrink or settle. Zero VOC emission. Chemically inert. Insect resistant. Mold Proof. Insoluble in water. Disadvantages: Fragile at the low densities needed to achieve the quoted R value and, like all foams, it is more expensive than conventional fiber insulations. In 2010, the Ontario Building Code Commission ruled that AirKrete did not conform to requirements for a specific application in the building code. Their ruling states "As the proposed insulation is not impermeable, it could allow water or moisture to enter the wall assembly, which could then cause damage or deterioration of the building elements." As of 2014-08-21, the domain airkretecanada.com appears to be abandoned.
;Polyisocyanurate: Typically R-5.6 or slightly better after stabilization – higher values in stabilized boards. Less flammable than polyurethane.
;Phenolic injection foam: Such as Tripolymer R-5.1 per inch. Known for its air sealing abilities. Tripolymer can be installed in wall cavities that have fiberglass and cellulose in them. Non-hazardous. Not restricted by depth of application. Fire resistant – flame spread 5, smoke spread 0 – will not smoke at all upon direct contact with flame and is a two-hour firewall at a, or normal stud wall, application per ASTM E-199. Great for sound deadening, STC 53 ; does not echo like other foams. Environmentally friendly. Non-expansive. Fully sustainable: Consists of phenolic, a foaming agent, and air. Blown with air. Nontoxic, even during application. Does not shrink or settle. Zero VOC emission. Chemically inert. Insect resistant. Mold Proof. Insoluble in water. Disadvantages: Like all foams, it is more expensive than conventional fiber insulations when only comparing sq ft pricing. When you compare price to R value per sq ft the price is about the same.
;Polystyrene and extruded polystyrene )
;Closed-cell polyurethane: White or yellow. May use a variety of blowing agents. Resistant to water wicking and water vapor.: An example of a commercial closed-cell polyurethane product:

Ecomate

R-8 per inch. Ecomate is a trademarked foam blowing agent technology and family of polyurethanes which has a neutral impact on the environment. The worldwide patent was awarded to Foam Supplies Incorporated in 2002. This is a new generation eco-friendly foam blowing agent that is free of chlorofluorocarbons, hydrochlorofluorocarbons, and hydrofluorocarbons based on naturally occurring methyl methanoate.
;Open-cell polyurethane: White or yellow. Expands to fill and seal cavity, but expands slowly, preventing damage to the wall. Resistant to water wicking, but permeable to water vapor. Fire resistant. Some types of polyurethane insulation are pour-able.
Here are two commercial open-cell, low-density polyurethane products:
;Icynene: Icynene is a trademarked brand of isocyanate open-cell spray foam from Huntsman Building Solutions. The classic version has a thermal resistance of 3.7 per inch and other versions have even higher values. The formula also includes a flame retardant. Icynene uses water for its spray application and the chemical expansion is caused by the carbon dioxide generated between the water and isocyanate material. Icynene will expand up to 100 times it original size within the first 6 seconds of being applied. Icynene contains no ozone-depleting substances such as CFCs, HFC's, HCFC's. Icynene contains volatile organic compounds. Icynene will not emit any harmful gases once cured. Icynene has a Global warming potential of 1. Flammability is relatively low. Icynene maintains its efficiency with no loss of R-Value for the life of the install. Icynene is more expensive compared to traditional insulation methods. Any potential for harm is primarily during the installation phase and particularly for installers. The manufacture of icynene involves many toxic petrochemicals.
;Sealection 500 spray foam:R-3.8 per inch. a water-blown low density spray polyurethane foam that uses water in a chemical reaction to create carbon dioxide and steam which expands the foam. Flame spread is 21 and smoke developed is 217 which makes it a Class I material. Disadvantages: Is an Isocyanate.