Fluke Ti32 User Manual

Applications for Thermal Imagers

Moisture in
building envelopes

The presence of moisture in building envelopes, whether from leak­age or condensation, can have serious consequences. For example,
moisture in insulation reduces its insulating capability, causing heating
and/or cooling losses and wasting energy. Moisture can also cause
structural deterioration and foster the growth of mold, while a serious
roof leak can damage or destroy a building’s contents.

Application Note

Unexpected moisture intrusion in a ceiling.

Thermography, also known as
thermal imaging, is well suited to
identifying wet spots in building
envelopes. As a diagnostic tech­nique, thermography captures
two-dimensional images of the
apparent temperatures of equip­ment and structures. Thermal
images can reveal anomalies in
roofs and walls that can indi­cate the presence of moisture as
buildings cool after having been
under a thermal load. This hap­pens because water conducts
and stores heat better than most
building materials. So, when a
roof or wall cools, wet or damp
areas cool slower than dry areas
and show up as “hot spots” on
thermal images.

The following discussion
focuses on using thermal or
infrared (IR) imaging to check
for moisture in the envelopes of

industrial, commercial and
institutional buildings, including
moisture in roofs, walls and
insulation.

What to check?

Check the outside walls and
roofs of buildings after they have
experienced a thermal load, e.g. a
solar load on a hot, dry day. East­facing walls might be checked
in the afternoon and (in the
Northern Hemisphere) south- and
west-facing walls and roofs after
sundown. A significant thermal
gradient (15 or 20 %) between
the inside and outside is essential
in order detect thermal anomalies
attributable to the difference in
heat capacity between the
materials of construction and
the additional moisture load.

When potential wet spots in
exterior walls and roofs are
identified, follow up with an
inspection inside the building,
to further refine the outdoor find­ings. Inside inspections can also
independently pinpoint moisture
in ceilings and walls caused by
leaks, water pipe breaks, fire­sprinkler discharges or other
water-producing events. Fast
action with a thermal imager fol­lowing a water-producing acci­dent can identify which materials
must be dried or replaced.

For more information on Thermal Imagers

go to www.fluke.com/thermography

What to look for?

Collecting thermal images is a
good first step in analyzing a
structure and identifying sus­pected problem areas. Unlike
other moisture-detecting technol­ogies, such as meters, thermogra­phy requires no physical contact
with roofs, ceilings, walls or
floors. In addition, you can check
inaccessible areas and cover a
large area in a single image.

Regular building-envelope
inspections are key to prolonging
the lives of industrial, commer­cial and institutional buildings.

easier to spot where further
investigation is needed.

*The Fluke Ti20 comes with InSideIR™
analysis and reporting software with free
updates for the life of the product.

What represents a
“red alert?”

Give any building-envelope
condition that poses a safety or
health risk the highest repair
priority. Next, any roof leaks or
moisture conditions that threaten
production, electronic data, elec­tronic equipment or the integ­rity of the building itself should
receive immediate attention.

New construction and especially
new roofs should by thoroughly
inspected 6 to 9 months after
construction, while the structure
is still under warranty. That time
lag allows the structure to expe­rience the elements, hopefully
a rainy season. Then, perform
additional building-envelope
scans every two to five years.
Compare them to the original,
baseline images to establish
trends and determine remedies
to any deterioration. Experts
estimate that preventive main­tenance of this kind will double
the life your facility’s roof. Roof
inspections should be conducted
with the imager mounted on a
tripod, so that the technician can
concentrate on properly adjust­ing the camera to maximize the
thermal resolution and analyzing
the image.

Fluke thermal imagers now
include IR-Fusion®*, a technol­ogy that fuses a visual, or visible
light, image with an infrared
image for better identification,
analysis and image management.
The dual images are accurately
aligned at any distance height­ening details, making it much

What’s the potential cost
of failure?

Flat roofs are the parts of com­mercial, industrial and insti­tutional buildings that are the
most likely to fail, and they are
expensive to replace. Factors vary
so much from facility to facility
that it’s difficult to put a price on
roof replacements, but one expert
writing in 1989 came up with
a range of weighted averages
between $4.50 per square foot
for mechanically attached single­ply roofs and $8.00 per square
foot for coal-tar built-up roofs.*

Follow-up actions

Before checking your building
for moisture, be aware that this
kind of inspection constitutes
one of the most challenging uses
for IR thermography. Buildings
vary with respect to kind, use,
construction techniques, building
materials, size and so on.

*Source: Benchmark, Inc., Roof & Pavement
Consultants at 6065 Huntington Ct. NE, Cedar
Rapids, IA 52402 — 319-393-9100. The
figures are from an article, “Factors Affecting
Roof System Costs,” by Kent Mattison, P.E.

Safety tip:

Before starting a roof inspection, review the OSHA safety guidelines.
Then, whenever you’re up on a roof doing an inspection, have a
partner with you—day or night. Some people count on their radios.
A radio alone is not good enough. People have died on roofs right
next to their radios! Besides, your partner can mark the edges of
areas of wet insulation while you scan the roof and make images.

2 Fluke Corporation Thermal Applications: Moisture in building envelopes

Conducting effective thermal
building surveys requires under­standing construction methods
and the thermal characteristics
of building components, as well
as how to account for changing
thermal conditions within and
around buildings. Then, follow­ing the IR inspection, determine
where inside heat sources are
and whether they affected the
exterior images. Finally, perform
further analysis to confirm the
findings. Infrared inspections
provide the most cost effec­tive means of ensuring that the
roof is properly sealed, but the
presence of a thermal anomaly
does not indicate the presence
of moisture in the roof. It is
essential to follow up with core
samples and other techniques.
Reference ASTM C1153 Standard
practice for location of wet insu­lation in roofing systems using
infrared thermography.

When you have accurately
identified moisture in a building’s
envelope, targeted maintenance
work can be performed. If you
discovered the problem using a
thermal imager, use the software
that came with the instrument
to document your findings in a
report. Include a thermal image
and a digital image of the rel­evant area of the building. Such
reports are the best way to com­municate the problems you find
and to suggest repairs.

Fluke. Keeping your world
up and running.

Fluke Corporation
PO Box 9090, Everett, WA 98206 U.S.A.

Fluke Europe B.V.
PO Box 1186, 5602 BD
Eindhoven, The Netherlands

For more information call:
In the U.S.A. [phone] or
Fax [phone]
In Europe/M-East/Africa [phone] or
Fax [phone]
In Canada (800)-36-FLUKE or
Fax [phone]
From other countries [phone] or
Fax [phone]
Web access: http://www.fluke.com

©2005-2008 Fluke Corporation. Specifications
subject to change without notice. Printed in U.S.A.
10/2008 2519615 A-EN-N Rev C

Modification of this document is not permitted
without written permission from Fluke Corporation.

®