Closed Cell Foam

Typically oil-based, high density (1.25-2 pounds per cubic foot) hard foam. It is a fairly mature product that has been out for 30+ years. Made of 2 parts, it catalyzes when mixed and cures quickly. Air bubbles inside (cells) do not burst, hence the ‘closed cell’ designation.


  • Good air seal.
  • Will stick to dirty surfaces.
  • Low shrinkage, so it won’t pull away from edges if installed correctly.
  • High R-value/inch. Reduces moisture transfer.


  • Strong chemicals involved.┬áIn small quantities it isn’t a big deal, but doing whole new houses all humans are recommended to stay away for several days.
  • It is oil based, so it is not very “green”.
  • More expensive than all other common insulation types.
  • When it cures it exerts a lot of pressure and will break drywall and bend window and door frames so they won’t shut.
  • All forms are somewhat combustible.
  • Occupants need to leave the home for 24 hours while product off gasses.
  • Does not prevent radiant heat transfer – the primary source of heat-flow in and out of buildings.


Radiant Barrier
Rock Wool
Air Krete
Open Cell Foam
Closed Cell Foam