MOISTURE METER STUDY - CONTENTS: Field study compares the ability of popular moisture and leak detection tools to find leaks in building wall cavities and ceilings. Importance of visual inspection in assessing the leak risk or mold, insect damage, or rot risk at buildings. Guide to detecting and evaluating leaks and water entry into buildings
POST a QUESTION or READ FAQs about how to use moisture meters to check for building leaks, hidden damage, mold, insects, rot - reliabilty, procedures, proper usage
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Moisture meter reliability for detection of building leaks or moisture problems:
Guide to Using Moisture Meters to Screen Buildings for Leaks, Moisture Traps, Rot, Insect Damage, or Mold. This article explains the use and reliability of different types of moisture detection equipment to find water entry problems on buildings. We demonstrate where moisture meters work successfully and where (and why) they don't. We explain the differences between pin type moisture meters and electronic sensor moisture measuring devices.
Our page top photo shows our client pointing to flood lines on a heating system expansion tank, indicating that this building was subject to severe deep flooding. We learned from neighbors that a nearby river had flooded this home and others in its neighborhood repeatedly over the 60 year life of the building.
Report on the Reliability of Moisture Meters to Screen Buildings for Hidden Moisture, Leaks or Mold Contamination
Question: will my inspector test for moisture?
I am scheduling a pre-purchase home inspection and my real estate agent asked a question about moisture detection: he wants to know if the home inspector will check the moisture level in Sheetrock? - C.W., New York, NY.
Reply: ... it depends ...
Moisture meters, particularly pin-type probing moisture meters that detect moisture by sending an electrical signal between two probes inserted into a material (such as the time-tested Delmhorst™ twin-point electronic resistance moisture meter shown at left) are one of the first tools that many building inspectors purchase after a flashlight, ladder, and screwdriver.
Relying on any test instrument alone, as we discuss at GAS DETECTOR WARNINGS , is not a good substitute for a careful inspection. While using a moisture meter is a
popular tool among home inspectors and building environmental inspectors or "mold investigators", and a useful one, the visual inspection of a building for
leak history is much more critical than a general "check" using a moisture meter.
After all, the building could have had a history
of leaks in the past, as well as hidden rot, insect damage, or mold, related to leaks or trapped moisture, but the
leak spot could happen to be dry at the time of testing.
evidence of moisture when using a moisture meter in a building is not evidence of absence of a history of building leaks, and there is a long list of visual clues that readily tell the story of a building's leak history or the risk of building flooding. .
So properly a moisture meter is, in our opinion, useful principally to confirm that a leak is current.
We also find moisture meters useful, particularly radio-signal based non-probing moisture meters such the Tramex™ electronic moisture encounter, to check for hidden leaks behind ceramic tile walls in bathrooms and kitchens where probing is impossible. Our photo (above left) illustrates use of a Tramex™ moisture encounter to check for leaks into the EIFS stucco covering of a building's window sill. Details are
at SIDING EIFS WALL LEAK POINTS.
And certainly "spot checks
for moisture" done randomly at a building would be nonsense.
Study Comparing the Effectiveness of Moisture Detection Methods in Buildings
In a field study this author (Daniel Friedman) conducted in February 2004 we compared the effectiveness of various methods to test for moisture in the walls of a home reported to have suffered leaks from ice dams at its roof eaves.
We surveyed the inside surface of building exterior walls of the entire second floor front and rear building surfaces using the following methods:
Surface checks for evidence of moisture using a Tramex™ Moisture Encounter (shown above on an exterior window sill). This instrument is non-invasive, does not leave surface marks, and can be slid rapidly along building surfaces, making it easy to scan large areas for moisture. [Tramex also makes pin-type moisture meters like the model shown at left.]
Surface checks for evidence of moisture using a Delmhorst™ pin-type moisture meter with short pin probes that penetrated less than 3/4" into the building drywall. This type of water leak detection device is the most commonly-used one during home inspections.
Long probe moisture meter: Spot checks for moisture at highly-suspect areas, wall tops, around windows, and wall bottoms above baseboard trim using a long-probe Delmhorst pin-type moisture meter.
Test cuts into wall and ceiling cavities at highly-suspect areas for recent leaks, including wall tops, around windows, and wall bottoms above baseboard trim using a drywall knife and making 2" x 4" or 4" x 4" inspection openings to examine the wall insulation, wall framing, cavity side of drywall, and the inner surface of exterior building wall sheathing.
Our photo (left) shows a wall test cut made and then closed over a window and where from outside we had seen evidence of leaks into the building soffits - caused by ice dams.
Note: destructive or invasive inspection practices are not normally used during a pre-purchase home inspection but may indeed be appropriate during more extensive building investigations (with owner permission). [In this case we were studying the building for an insurance company who was investigating ice dam leaks.]
Demolition and strip cuts or complete removal of the drywall throughout the suspect building walls of the second floor of the home to expose all of the wall cavity framing and exterior wall sheathing, including demolition of a bathroom that had been built using ceramic tile wall covering.
Use of infrared or thermography to detect moisture in buildings is a widely-used practice that was not tested during this study. Our OPINION is that not only do IR or thermographic scans of buildings face the same limitations of moisture meters (old leaks are not detected), but as well, the operator needs the skill and experience in IR image interpretation to account for other sources of temperature differences across a building that may be caused by other conditions than water leaks.
Conclusions of Moisture Detection Equipment Study
Any moisture meter properly used did a good job of detecting moisture that had penetrated the building interior drywall provided that the drywall was still sufficiently damp at the time of our inspection.
An electronic moisture encounter could detect wet insulation in the wall cavity that had not yet led to drywall in that location being sufficiently wet to show up using a surface or pin type moisture detector.
But the same device could be "fooled" into reporting wet conditions where there were none if there any metallic substance was in the wall cavity, including electrical wiring, plumbing pipes, expanded metal lath, and foil-faced building insulation.
A long-pin type moisture meter was capable of detecting moisture in the wall cavity insulation that did not show up in surface tests, and might not show up using an electronic moisture encounter, provided that the inspector was astute enough or lucky enough to probe exactly correctly to stab into moisture.
For example, in one wall cavity water from a roof leak was running down the side of a wall stud (photo at left) but staying close to the exterior wall. This type of leak was missed by most of the test and inspection methods, but would show up eventually in the ceiling below if the leak continued long enough or in great quantity.
Old leaks were not detected: None of the moisture detection devices was able to detect points of prior leakage that had dried at the time of the study, but indeed when we demolished the building interior walls, we found both water stains and carpenter ant damage in the bathroom walls from old plumbing leaks.
Pin-type moisture meters, in the hands of a very experienced inspector, might detect a suggestion of previous, leaks in areas dry at the time of inspection (provided the surface can be probed AT ALL and is not covered by a hard surface such as ceramic tile) because on occasion mineral salts left behind when a leaked-into-area dries will give a higher moisture meter reading (higher electrical conductance) than surrounding areas even though the surface is dry.
Visual inspection of a building, its construction, materials, maintenance history, ventilation, and the myriad of visual clues that can indicate a history of water entry, leaks, or trapped moisture is critical in assessing the level of risk of moisture or leaks at a building. Articles shown at the left of this page discuss various inspection points that indicate a history of building leaks, flooding, moisture, or mold problems.
Our photo (left) of a window in a shower and duct-tape "repairs" along the window edge would be a very strong suggestion of a leak history in this bathroom shower - without using any moisture meter instrument whatsoever. Similarly, the mud-line on the heating system expansion tank shown at the top of this page shows that the building had actually been flooded.
Observing evidence of the frequency, extent, source, and causes of leaks, water entry, and actual building flooding is a critical step in evaluating a building as well as in planning the cure for building leaks, water entry, and mold.
Home buyers and home owners are right to worry about building leaks and moisture - water where we don't want it is
at the top of the list of sources of building problems. If you have a
particular reason to be suspicious about something be sure to let the
Also see VISUAL PERCEPTION ERRORS - an exploration of the theory of vision and visual errors that illustrates to building inspectors that it is important to actually inspect, and to be aware of distractions that keep us from "seeing" critical clues even if we are "looking" right at them - inattentional blindness.
Watch out for "show and tell" tools that impress the client during a home inspection but are a poor
substitute for doing a good job.
OPINION: Of these questionable practices, the most hilarious (and dishonest) use of thermography that we have found popular in some areas is that made by "mold inspectors" and a few mold remediation companies who claim that their IR camera is a "mold detector".
Like any good fib, there' s just enough truth in the statement to confuse things. Sure, a leak may show up under a thermographic scan, and a leak into building cavities are a high risk for mold. But what about old leaks, now dry, that launched a large mold problem?
What about air leaks that lose energy and show up on the thermographic scan, but have not led to moisture and mold contamination? [Perhaps some readers will recall the old replacement window scam that used light meters as "energy loss" meters. ]
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which moisture meter to use before re-painting T-111 exterior siding
(Mar 28, 2015) Ruth said:
T-1ll exterior siding installed one year ago has developed hairline cracks. According to the manufacturer of Protek Elastoprime the plywood must be thoroughly dry before application of this coating. To determine if the wood is dry enough, which type of moisture meter, if any, do you recommend?
Reply: when, where, how to check for moisture before re-painting
I would use a pin type moisture meter for measurements that are principally concerned with the surface or near-surface moisture of the siding.
If I were looking for evidence of a leak deeper in the wall cavity I'd use an electronic type moisture meter.
But take care: I've investigated paint failures at sites where the painter used a moisture meter and asserted that the siding was dry enough to paint. The problem was that she did not make measurements in the best spots: before painting walls on a particular side of the building, measure the locations on that side that are most-likely to need more drying time.
For a comprehensive look at avoiding paint failure take a look at You might want to check this more comprehensive advice on causes of paint falures:
see PAINTING MISTAKES.
Off the cuff, for the case you cite, points at which I'd check for moisture before painting include (as examples as this can't be a comprehensive list):
areas lowest on the wall
areas at intersections of trim and siding, especially horizontal trim
areas that are longest in shade
areas where stains or other old visual clues suggest there have been paint problems in the past
areas of the T111 siding that needed repair prior to the paint job.
the last areas of the T1-11 siding that were primed prior to application of the finish coat - as we want to be sure those are thoroughly dry.
For other readers, more about Protek's Elastoprime, a product designed for restoration of T-111 exterior siding, is at the company's website www.protek-usa.com
Question: how to detect leaks before they do major damage
(Jan 8, 2015) kathy said:
I live in a condo and have had 2 major inside wall leaks in 3 years . I would like to be able to detect the leak before it causes major damage . What device would you recommend
A more useful answer would need to be based on knowing more about your building, its construction, materials, and leak history - things that an experienced inspector could consider when on-site. But in general, I would not rely on a moisture meter alone to detect leaks. I'd start with the building leak history to understand where leaks have already occurred, why, and what was done to correct them - and thus I'd ask if the repairs were adequate in extent and quality.
I'd continue with a visual inspection of the building to identify important leak risk points. My view is that this visual inspection is most important since no instrument is completely reliable at determining the presence, age, extent of building leaks.
I'd continue with an assessment for hidden damage where leaks have already occurred.
IR or thermal imaging is used by some inspectors to look for leaks since we can stand back and look at a large area at once, but its efficacy depends on how current the leak is as well as various temperatures and site conditions
Moisture meters that use a pin sensor or that use an electronic signal also only work if moisture is present at the spot where the test is performed.
I worry that by the time you detect a leak using any method you will already be at a point where the wet materials need to be excised as well as the leak repaired.
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Mark Cramer Inspection Services Mark Cramer, Tampa Florida, Mr. Cramer is a past president of ASHI, the American Society of Home Inspectors and is a Florida home inspector and home inspection educator. Mr. Cramer serves on the ASHI Home Inspection Standards. Contact Mark Cramer at: 727-595-4211 mark@BestTampaInspector.com
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Books & Articles on Building & Environmental Inspection, Testing, Diagnosis, & Repair
Design of Wood Structures - ASD, Donald E. Breyer, Kenneth Fridley, Kelly Cobeen, David Pollock, McGraw Hill, 2003, ISBN-10: 0071379320, ISBN-13: 978-0071379328
This book is an update of a long-established text dating from at least 1988 (DJF); Quoting: This book is gives a good grasp of seismic design for wood structures. Many of the examples especially near the end are good practice for the California PE Special Seismic Exam design questions. It gives a good grasp of how seismic forces move through a building and how to calculate those forces at various locations.THE CLASSIC TEXT ON WOOD DESIGN UPDATED TO INCLUDE THE LATEST CODES AND DATA. Reflects the most recent provisions of the 2003 International Building Code and 2001 National Design Specification for Wood Construction. Continuing the sterling standard set by earlier editions, this indispensable reference clearly explains the best wood design techniques for the safe handling of gravity and lateral loads. Carefully revised and updated to include the new 2003 International Building Code, ASCE 7-02 Minimum Design Loads for Buildings and Other Structures, the 2001 National Design Specification for Wood Construction, and the most recent Allowable Stress Design.
Diagnosing & Repairing House Structure Problems, Edgar O. Seaquist, McGraw Hill, 1980 ISBN 0-07-056013-7 (obsolete, incomplete, missing most diagnosis steps, but very good reading; out of print but used copies are available at Amazon.com, and reprints are available from some inspection tool suppliers). Ed Seaquist was among the first speakers invited to a series of educational conferences organized by D Friedman for ASHI, the American Society of Home Inspectors, where the topic of inspecting the in-service condition of building structures was first addressed.
Defects and Deterioration in Buildings: A Practical Guide to the Science and Technology of Material Failure, Barry Richardson, Spon Press; 2d Ed (2001), ISBN-10: 041925210X, ISBN-13: 978-0419252108. Quoting: A professional reference designed to assist surveyors, engineers, architects and contractors in diagnosing existing problems and avoiding them in new buildings. Fully revised and updated, this edition, in new clearer format, covers developments in building defects, and problems such as sick building syndrome. Well liked for its mixture of theory and practice the new edition will complement Hinks and Cook's student textbook on defects at the practitioner level.
Masonry structures: The Masonry House, Home Inspection of a Masonry Building & Systems, Stephen Showalter (director, actor), DVD, Quoting: Movie Guide Experienced home inspectors and new home inspectors alike are sure to learn invaluable tips in this release designed to take viewers step-by-step through the home inspection process. In addition to being the former president of the National Association of Home Inspectors (NAHI), a longstanding member of the NAHI, the American Society of Home Inspectors (ASHI), and the Environmental Standard Organization (IESO), host Stephen Showalter has performed over 8000 building inspections - including environmental assessments. Now, the founder of a national home inspection school and inspection training curriculum shares his extensive experience in the inspection industry with everyday viewers looking to learn more about the process of evaluating homes. Topics covered in this release include: evaluation of masonry walls; detection of spalling from rebar failure; inspection of air conditioning systems; grounds and landscaping; electric systems and panel; plumbing supply and distribution; plumbing fixtures; electric furnaces; appliances; evaluation of electric water heaters; and safety techniques. Jason Buchanan --Jason Buchanan, All Movie Review
Straw Bale Home Design, U.S. Department of Energy provides information on strawbale home construction - original source at http://www.energysavers.gov/your_home/designing_remodeling/index.cfm/mytopic=10350
More Straw Bale Building: A Complete Guide to Designing and Building with Straw (Mother Earth News Wiser Living Series), Chris Magwood, Peter Mack, New Society Publishers (February 1, 2005), ISBN-10: 0865715181 ISBN-13: 978-0865715189 - Quoting: Straw bale houses are easy to build, affordable, super energy efficient, environmentally friendly, attractive, and can be designed to match the builder’s personal space needs, esthetics and budget. Despite mushrooming interest in the technique, however, most straw bale books focus on “selling” the dream of straw bale building, but don’t adequately address the most critical issues faced by bale house builders. Moreover, since many developments in this field are recent, few books are completely up to date with the latest techniques. More Straw Bale Building is designed to fill this gap. A completely rewritten edition of the 20,000-copy best--selling original, it leads the potential builder through the entire process of building a bale structure, tackling all the practical issues: finding and choosing bales; developing sound building plans; roofing; electrical, plumbing, and heating systems; building code compliance; and special concerns for builders in northern climates.
Carson, Dunlop & Associates Ltd., 120 Carlton Street Suite 407, Toronto ON M5A 4K2. Tel: (416) 964-9415 1-800-268-7070 Email: firstname.lastname@example.org. The firm provides professional home inspection services & home inspection education & publications. Alan Carson is a past president of ASHI, the American Society of Home Inspectors. Thanks to Alan Carson and Bob Dunlop, for permission for InspectAPedia to use text excerpts from The Home Reference Book & illustrations from The Illustrated Home. Carson Dunlop Associates' provides extensive home inspection education and report writing material.
The Illustrated Home illustrates construction details and building components, a reference for owners & inspectors. Special Offer: For a 5% discount on any number of copies of the Illustrated Home purchased as a single order Enter INSPECTAILL in the order payment page "Promo/Redemption" space.
TECHNICAL REFERENCE GUIDE to manufacturer's model and serial number information for heating and cooling equipment, useful for determining the age of heating boilers, furnaces, water heaters is provided by Carson Dunlop, Associates, Toronto - Carson Dunlop Weldon & Associates Special Offer: Carson Dunlop Associates offers InspectAPedia readers in the U.S.A. a 5% discount on any number of copies of the Technical Reference Guide purchased as a single order. Just enter INSPECTATRG in the order payment page "Promo/Redemption" space.
The Home Reference Book - the Encyclopedia of Homes, Carson Dunlop & Associates, Toronto, Ontario, 25th Ed., 2012, is a bound volume of more than 450 illustrated pages that assist home inspectors and home owners in the inspection and detection of problems on buildings. The text is intended as a reference guide to help building owners operate and maintain their home effectively. Field inspection worksheets are included at the back of the volume.
Special Offer: For a 10% discount on any number of copies of the Home Reference Book purchased as a single order. Enter INSPECTAHRB in the order payment page "Promo/Redemption" space. InspectAPedia.com editor Daniel Friedman is a contributing author.
Special Offer: Carson Dunlop Associates offers InspectAPedia readers in the U.S.A. a 5% discount on these courses: Enter INSPECTAHITP in the order payment page "Promo/Redemption" space. InspectAPedia.com editor Daniel Friedman is a contributing author.
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