Navy Study

Summary of NCEL Technical Note N-1815

Naval Civil Engineering Laboratory- Port Hueneme, California
Sponsored by Naval Facilities Engineering Command
Conducted by: R.L. Alumbaugh, E.F. Humm, and John R. Keaton
July 1976- January 1986

Background: This study was initiated by the NCEL at the request of NAVFAC in a continuing effort to reduce maintenance and repair costs of the extensive roofing systems at Naval installations. This study was limited to Spayed Polyurethane Foam (SPF) and Coating systems, and was intended to generate data that provides guidelines for coating systems to protect SPF materials used in the roof system.

The principal objectives of this investigation were to determine how long the candidate SPF roofing system perform satisfactorily when exposed to the weather and which of the candidate systems were superior. The SPF systems were exposed to three different climatic conditions: A seashore site at Port Hueneme, CA, a desert site at China Lake, and a mountain site at Pickle Meadows in the high Sierras.

Their experience had shown that if the SPF is properly applied to a suitably prepared substrate, the performance of the system is primarily dependent on the performance of the protective elastomeric coating system. That is, with a high quality foam, if the coating performs well, the SPF roofing system as a whole can generally be expected to perform well.

The performance of the coated SPF panels at the three sites was monitored periodically. The performance characteristics of the various systems were determined at periodic intervals by visual inspections and ratings. The characteristics considered related primarily to the coatings and included adhesion, blistering, checking, cohesion, cracking, flaking, peeling, pinholing, and hail and bird damage. All of these factors were then considered in assigning an overall performance rating as follows:

10 = Excellent The system is performing without any noticeable deterioration.
9 = Very good Only very minor deterioration of the system.
8-9 = Good Although the system shows some deterioration, it is not yet serious.
7 = Poor System deterioration is becoming serious. Remedial action will be required in the near future.
6-0 = Failed Deterioration of the system has advanced to the point of requiring immediate maintenance.

Results of Field Investigations:
Of the 54 systems tested, only 11 were rated Very Good (9) or Excellent (10) at all three sites. There were 2 Silicone systems, 5 Acrylics, 3 Urethanes and 1 Urethane-Silicone. (Tables 12,13) Of those we have extracted the following for comparison: (Note: All three of these systems were set out at the same time in December of 1978. The results recorded here were observed in January of 1986. total exposure time was 7 yr. 11 months at that time.)

Silicones: Moisture-Cured-
System 2G: Dow Corning #3-5000 construction Coating, Gray Base and White Top Coat with Granules over CPR Upjohn 485-2 foam was rated Excellent (10, 10, 10) at all three sites. (Note: the other two Dow Silicone systems (2, 2A) in the study without granules were downgraded due to cracking, checking, bird pecking.)

System 6G: United Coatings “Diathon” with granules over CPR Upjohn 485-2 foam. At all three sites was rated Excellent (10-,10,10), At the seashore site, minor blistering caused slight downgrade. The other two Diathon systems (6,6A) without granules were both rated lower due to pinholing, checking, cracking and bird pecking.