Abacus Group Ltd. (201)
384-5552
info@abacusgrp.com
ASHLAND CHEMICAL PLANT
EASTON, PA.
Infrared
Roof Survey
Ashland Chemical
Investigation:
3/26/96
Table
of Contents
Abstract
Profile
Roof
Evaluation
Roof
Illustrations
ABSTRACT
The
purpose of the infrared survey is to detect and define
moisture damaged roofing components. The survey utilizes
thermal imagery to identify moisture within the roof
system, without the use of destructive testing.
The basic
tool of ABACUS GROUP LTD. Infrared Roof Survey is the
Agema Thermovision 450 Infrared Thermal Measurement and
Imaging System, using the state of the art
Electro-optical scanning mechanism, the new SPRITE
infrared detector, video interface and control
electronics and microprocessors for video output. The
infrared camera converts electromagnetic thermal energy
radiated from an object into electronic video signals.
These signals are amplified and transmitted to the video
processing part of the camera where the signals are
further amplified and the resultant image is displayed on
the viewfinder. The camera senses the intensity of
thermal radiation from the roof surface, and displays a
monochrome image whose density corresponds to the
radiation intensity. The radiant energy levels are
interpreted as surface temperatures.
Water
enters the roof system by means of holes, splits or
faulty flashings, causing the roofing components (i.e.,.
decking, insulation) to become wet. The wetter areas
store more heat from daytime solar loading and remain
warmer at night. Reduced thermal value of water damaged
insulation and/or decking materials also allows for heat
transfer of interior energy through the wet components
areas during the colder months. It is this thermal
radiation of water present in the roof that the infrared
camera records. The hot spots are visible on the surface
of the roof when viewed through the infrared camera.
Moisture
entering the roof system at penetrations, base flashings,
and masonry walls that does not affect the insulation
will not be detected by the infrared camera because the
moisture runs directly into the building interior,
leaving the insulation unaffected. Masonry walls can be
scanned for moisture entrapment under certain conditions.
For more information on masonry wall scans, contact ABACUS.
The roof
top is scanned at night. Scanning at night allows for
sufficient cooling of the roof surface and eliminates
solar reflection resulting in a more accurate scan.
Upon
request, certain portions of the thermal information
obtained during the scan can be videotaped for further
analysis. This information is later digitized using the
new Data Translations High Resolution Frame Grabber,
which digitizes the real-time video signal for further
processing by the IRIS Image Processing Computer System.
The
thermal image signal is broken down into a 16 color
temperature scale, and temperatures/colors are assigned
to the radiational intensities of the image. The
information can now be presented as colorized
thermograms, with different colors representing different
roof surface temperatures. Variables that can affect the
thermal radiation include wind velocity, cloud coverage
and material density. A color bar along the bottom of the
thermograms indicate temperatures in ascending degrees
with warmer areas (typically the wettest areas) at the
right of the bar. Also included are Black and White
Thermograms that depict the same image seen and recorded
on the roof during the survey. Corresponding visible
light photographs help to orientate the thermograms, as
well as give clues to water entry points.
Areas of
wetness obtained, if any, are marked on the roof surface
with yellow spray paint during the IR survey. The areas
indicated represent findings identified during the IR
survey. Repairs to the roof system are recommended to be
performed as soon as practical. Please note that the
findings of the infrared moisture survey can only be
accurate and representative for the time of the moisture
survey. Additional moisture intrusion into the roofing
components upon completion of the survey will typically
tend to enlarge the areas of subsurface moisture
identified.
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PROFILE
BUILDING:
Ashland Chemical Buildings #3 and #9, 400 Island
Park Road, Easton, PA
SCANDATE:
3/26/96
ROOF
SQUARE FOOTAGE EXAMINED: approximately 20,000 Sf
NUMBER
OF ROOF ANOMALIES DETECTED: Five (5)
Building #9- 3
Building #3- 2
TOTAL
WET COMPONENTS: 1,956 square feet
Building #9 1,896 Sf
Building #3 60 Sf
EXTERIOR
TEMPERATURE: 49 Degrees F.
HUMIDITY: 38%
WIND VELOCITY: calm
SKIES: clear
ROOF
COMPOSITION: Deck- steel and/or concrete
Roof Insulation- rigid board
Roof Covering- EPDM (Bldg. #9), Built up roof
(Bldg. #3)
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ROOF EVALUATION
The
infrared roof moisture survey was conducted in an attempt
to locate and define areas of moisture damaged roofing
components. The survey was conducted on March 26,1996, at
approximately 6:00 p.m. Scanning during the night hours
is necessary for certain temperature differentials to
take place, allowing the thermal anomalies to appear.
The
infrared camera system views the entire roof surface.
Large areas of the roof can be scanned at once, and
problem areas are easily isolated and outlined with spray
paint.
General
atmospheric conditions were optimal during the survey.
Clear skies, low humidity and minimal wind velocity
insure accurate thermal readings. The thermal signals
were clearly transmitted from the roof surface.
Substantial solar loading and roof surface temperature
reduction during the evening contributed to the survey
results.
BUILDING
#9
This
building is roofed with a mechanically fastened EPDM
single ply roof system over a fibrous insulation board.
Three (3) areas of saturated insulation were detected,
totaling approximately 1,896 square feet.
Two (2) of
the thermal anomalies are located around the two large
mechanical units. Roof traffic and physical damage to the
membrane are likely causes of water leakage. Anomaly #3
extends for nearly one hundred feet along the west
perimeter edge of the roof. In all three (3) anomalies,
thermographic imagery depicted 90% to 100% saturated
insulation.
BUILDING
#3
Two (2)
thermal anomalies consistent with moisture affected
insulation patterns were detected on this built up roof.
Both are located along the east perimeter of the roof,
and total 60 square feet.
The
anomalies correspond to the reported interior leak
locations.
Mechanical
unit and perimeter edge flashings should be checked for
deterioration and repaired accordingly. Also, a series of
pitch boxes on the roof appeared to be deteriorated, and
may be allowing direct water entry.
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ROOF ILLUSTRATIONS
During the
infrared survey of the roof, a varied selection of
thermal data was recorded on videotape and later
processed to create the following thermograms. Each set
of photographs depicts one sample area as a colorized
thermogram, black and white thermogram, and a visible
light photograph. The video taped data is also available
for viewing upon request. The thermal data recorded is
for illustrative purposes only.
Anomaly
#2
|
a.
Colorized Thermogram-This portion of the anomaly
#2 is located along the perimeter edge of the
roof, and reveals moderately wet insulation. This
area is not fully saturated, however, with ear
rainfall, the anomaly size may enlarge.
|
 |
b. Black and White
Thermogram-Moisture is seen spreading between
insulation boards. |
 |
c. Visible Light Photo-Possible
water entry points may include punctures in the
membrane as well as leaking membrane seams. |
Anomaly #2
|
a.
Colorized Thermogram - This portion of the
anomaly #2 is located along the perimeter edge of
the roof, and reveals moderately wet insulation.
This area is not fully saturated, however, with
ear rainfall, the anomaly size may enlarge.
|
 |
b. Black and White Thermogram -
Moisture is seen spreading between insulation
boards. |
 |
c. Visible Light Photo -
Possible water entry points may include punctures
in the membrane as well as leaking membrane
seams. |
The colorized thermogram depicts moisture
affected roofing components, if any, as changes in color.
The colors white, tan, yellows and greens, generally
indicate the wettest insulation or decking. The color
dark blue indicates wet or damp substrate. These colors
are usually found at the edges of the anomaly area, or in
areas not yet saturated. Reds and black indicate dry
roofing substrate.
The black
and white thermogram depicts moisture saturation
conditions as shades of grey. The whitest areas generally
indicate the wettest substrate. The blackest portions
indicate dry roofing. These calibrations were set using
readings of wet and dry roof components. The white
portions of the thermogram are created by the wet
roofing, which emits higher levels of infrared thermal
energy than dry materials, when scanned during the night.
For more
information on energy analysis studies, contact Abacus.
The visible light photographs are generally taken from
the same location as their corresponding thermograms and
depict a similar field of view.
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