Jul 2012

Elastomeric Insulation

Elastomeric insulation, also known as closed cell foam insulation, is a flexible type of plastic insulation close to the consistency of rubber. It is normally used as insulation for piping and ducting but is known to be used as insulation for subfloor spaces. It is sold either as flat sheets to be wrapped around large pieces or in a tubular shape, ready to be placed over piping. Depending upon the manufacturer and formula, when burned its heat release is typically greater than cellulose material and in some cases can approach the heat release for polyurethane, which can vary from 10,000 to 20,000 BTU/lb. (23 to 46 MJ/kg). For comparison the heat of combustion for gasoline is 20,000 BTU/lb. (46 MJ/kg).

When used, Risk Logic suggests that the product be FM Approved especially in areas where sprinkler protection might not otherwise be needed, such as noncombustible areas above ceiling spaces or noncombustible subfloors.

When choosing an FM Approved product, care should be taken to ensure that not only the manufacturer makes FM Approved products, but also that the particular model coming from their facility that services your part of the world is certified to make that FM Approved model.

As an example, we chose to note that Amracell makes several different pipe insulations in several different facilities throughout the world, though not all of them make the same models that are FM Approved. Their Germany facility makes several different products that are FM Approved while their China facility makes several different products and they’re not all the same models and are not all FM Approved.

Care must also be taken in regards to the limits of the FM Approval. Some products are limited by the overall insulation thickness on the shape to be insulated, or the size duct/pipe to be insulated.

In areas not otherwise needing sprinklers, install FM Approved insulation subject to the limitations of its approval. The insulation may also be used in sprinklered areas, again subject to the limitations of its approval.

Insulation that is not FM Approved (such as polyurethane), or that is approved and used beyond its limitations can be used under the following conditions:

  • Install a wet-pipe ceiling sprinkler protection providing a minimum 0.20 gpm/sq. ft. density over the most remote 2,000 sq. ft. using minimum K5.6, ordinary temperature rated heads, plus a 250 gpm hose stream allowance. Other construction/occupancy conditions may require a more stringent design.
  • Limit vertical runs of insulation to 10 ft.
  • Limit horizontal widths of ducting or pipe clusters to 4 ft.
  • Provide minimum 10 ft. separation between horizontal runs of ducts and pipe clusters.
  • Provide wet-pipe sprinkler protection under insulation widths greater than 4 ft.

In sprinklered areas, in lieu of limiting the length of the vertical and horizontal runs:

    • Sheath the insulated pipes and ducting with minimum 26 ga. steel or 0.032 in. aluminum.


  • Apply an FM Approved fire retardant coating listed as suitable for use over polystyrene (heat of combustion 18,000 BTU/lb. [41.9 MJ/kg]). Remove any facing on the insulation and install the coating per its approval limitations.

The sheathing/coating solution can be used for the entire insulation or to create breaks as outlined above.

Risk Logic can help you choose the correct insulation for your pipe or ducting. Please contact us for any additional information.