NAVY STUDY
Summary of NCEL Technical Note N-1815
"INVESTIGATION OF SPRAY-APPLIED POLYURETHANE FOAM ROOFING SYSTEMS-II"
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.)
Acrylics:
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.
SYSTEM 24G:SWD URETHANE
COMPANY'S "1929F" WITH GRANULES OVER SWD 525-2.5 FOAM. RATED EXCELLENT
(10,10,10) AT ALL THREE SITES. THERE WAS NO DETERIORATION.
