Spray Foam Insulation Pros and Cons

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R-values of rigid and liquid foam insulationThere are several types of foam insulation used in the walls and ceiling of residential and commercial buildings: rigid foam , rigid board made of mineral wool and liquid foam alternatives. Each has certain advantages and disadvantages. This article looks at the last option – rigid foam insulation.

What is it?

Spray foam insulation was extremely popular back in the 1970s and 1980s, when homeowners concerned with scary fuel prices decided to retrofit insulation. At that time, urea formaldehyde was often used, though it had problems. An alternative was polyurethane foam, though changes in legislation and taxes on the CFCs used to install it (intended to discourage their use and save the ozone layer) eventually killed that option. Today, spray foam insulation is back.

Polyurethane foam is available, as is an alternative called Icynene. Air Krete, which first appeared in the 1970s, is also still on the market.

Icynene Insulation

  • Icynene provides roughly R-3.6 per inch and creates an airtight seal.
  • Since the product is airtight, it can replace the need for a vapor barrier in some climates.
  • Icynene does not sink, settle or sag, so its R-value remains constant over time.
  • No CFCs or HCFCs are used in its production.
  • It is of no nutritive value to termites and produces no gases.
  • Icynene is sprayed by a trained applicator into open wall spaces and adheres to almost any surface.
  • Once it has adhered, Icynene expands to 100 times its original size, filling up the cavity.
  • Icynene can be applied to closed wall cavities by pouring a carefully-measured amount in through a hole and waiting for it to expand from the floor up. This provides roughly R-4 per inch.


Polyurethane Foam Insulation

  • Polyurethane foam now uses carbon dioxide gas as a blowing agent and there is no formaldehyde used in production.
  • Water-blown foam is also available, which contains an HFC expanding agent. Since there's no chlorine in the product, it does no damage to the ozone layer.


Air Krete Insulation

  • Air Krete is tolerated by most chemically-sensitive individuals.
  • It uses an inorganic substance containing magnesium oxide.
  • Air Krete gives roughly R-3.9 per inch.
  • The product does not settle, sink or change in R-value over time.
  • Air Krete must be applied by a trained individual.