Rigid Foam use limited at or below grade
8/4/1998

The National Pest Control Association (NPCA) will be joined by The International Code Council (ICC) in banning the use of rigid foam insulation below grade in areas with high rates of termite infestation. While NPCA recommends rigid foam not be used below grade at all the ICC is recommending its ban only in areas of ""very heavy" termite infestation in the ICC 1998 International One and Two Family Dwelling Code due out in the fall of 1998. Very heavy termite areas include California, the gulf coast states, and the southeast states of Georgia and South Carolina. The ban would include extruded or expanded polystyrene boards which are used under slabs, under or on the exterior of foundation walls, and at or above grade as a component of Exterior Insulation and Finish Systems (EIFS) - more commonly known as Synthetic Stucco to the lay person. If installed above grade a six inch clearance from the ground must be maintained. A study by a major US Corporation in Florida revealed an infestation rate of over 90% within 10 years in homes with exterior insulation at or below grade.

WHAT IS THE PROBLEM?

The problem is termites are virtually undetectable in rigid foam panels which can be as much as four inches thick. Termites prefer to tunnel inside the material as they migrate from the ground to the wood structure and back to the ground. One theory suggests termites like the elevated carbon dioxide levels found in the boards, as well as the ease of tunneling through the panels. The panels can not be treated with termiticides and the structure is rendered "untreatable" by the pest control operator (PCO) unless the material is removed from the building. Many PCOs are recommending moisture intrusion tests be performed by specialists to determine if a problem exists before they will inspect the home.

OTHER CONCERNS - WOOD ROT!

A second concern is wood rot from moisture penetration. Traditional EIFS buildings are designed to be moisture "barrier systems" stopping moisture at the exterior surface. If moisture enters the wall there is little chance of the system drying out and the wall cavity starts to rot. Elevated moisture levels (over 20%) lead to wood decay and fungus which is usually undetectable on EIFS systems until very serious damage has occurred to the wood framing. Decayed wood also increases the risk of infestation by termites and carpenter ants.

WHAT ARE PCOs DOING

NPCA is instructing PCOs not to treat EIFS homes with liquid termiticides, and to consider whether to issue any warranty or contract. Many PCOs are heeding the advise of NPCA and not issuing contracts on homes with EIFS exteriors and refusing to treat them. Others that are treating EIFS homes are disclaiming the EIFS portion of the home from any warranty or contract coverage should future infestation or wood rot damage be discovered.