Practical Aspects of Locating & Measuring Moisture in Buildings

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Mabel King
6 years ago
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Harriman Mason-Grant Consulting Portsmouth, NH

1 Practical Aspects of Locating & Measuring Moisture in Buildings BETEC -BEST Bugs, Mold & Rot IV Minneapolis, MN - June 2008 Lew Harriman Mason-Grant Consulting Portsmouth, NH LewHarriman@MasonGrant.com Practical Aspects of Locating & Measuring Moisture in Buildings 1of 35

2 Focus of this paper is on field investigations Part 1 - Locating areas of concern - IR cameras Examples of what IR cameras can do, what they cannot do, and why Part 2 - Measuring moisture - Moisture meters Types of meters, their advantages and limitations Practical Aspects of Locating & Measuring Moisture in Buildings 2of 35

Help you see The Big Picture of water damage & intrusion 3.

3 Using IR cameras for locating areas of concern 1. Infrared cameras only show surface temperature patterns 2. Help you see The Big Picture of water damage & intrusion 3. Investigating interior water damage is much simpler than exterior or forensic investigations Practical Aspects of Locating & Measuring Moisture in Buildings 3of 35

4 Two Examples Interior water damage - gypsum wall board With thoughtful use, cameras are very helpful Interior water damage - gym floor Cameras are nearly useless in this situation Practical Aspects of Locating & Measuring Moisture in Buildings 4of 35

water heater, flooded the floor over a weekend

5 Example 1 - Flood damage - Gypsum wall board Office condo in New Jersey Corroded connection to 5 gal hot water heater, flooded the floor over a weekend Practical Aspects of Locating & Measuring Moisture in Buildings 5of 35

6 Extract from video report Practical Aspects of Locating & Measuring Moisture in Buildings 6of 35

7 Note the insulating effect of the ceramic tile Janitor closet & water heater Practical Aspects of Locating & Measuring Moisture in Buildings 7of 35

8 Cove molding Note the insulating effect of the vinyl base molding Practical Aspects of Locating & Measuring Moisture in Buildings 8of 35

9 The visual camera shows the diffuser that s cooling the ceiling. Ceiling moisture? Practical Aspects of Locating & Measuring Moisture in Buildings 9of 35

10 Observations on the gypsum wallboard Very simple situation. Using IR, moisture is obvious Known, interior water source and location Single-story is affected, interior issues only Simple wall construction - Single layer is wet, and is (mostly) exposed to view rather than behind cabinets and furnishings Note the effect of vinyl cove molding and ceramic tile Insulates the surface from evaporative cooling of drying wall board Practical Aspects of Locating & Measuring Moisture in Buildings 10 of 35

11 Example 2 - Gymnasium floor moisture mapping Re-roofing project gone bad 3 of water, soaking maple sports floor over a long weekend No drying under the floor for two weeks floor is now cupping The issue: No question the floor must be replaced Is it all hopeless? Or can the IR camera show the worst parts, to save repair costs? The answer: No. The IR camera is no help. In fact, it shows false positives, because reflections look like high moisture, but are not. Practical Aspects of Locating & Measuring Moisture in Buildings 11 of 35

12 Gymnasium floor moisture mapping Practical Aspects of Locating & Measuring Moisture in Buildings 12 of 35

13 Observations on gym floor moisture mapping For the polished floor, the camera is useless Low surface emissivity obscures any thermal pattern Reflections generate strong (and false) patterns Thick wood flooring insulates surface from any evaporative cooling underneath For the wall, camera is quite helpful Non-insulated block responds VERY differently in wet areas Practical Aspects of Locating & Measuring Moisture in Buildings 13 of 35

14 Summarizing infrared moisture detection 1. Infrared cameras only show surface temperature patterns 1. They CANNOT see inside walls 2. Not all temperature patterns are moisture patterns meters remain mandatory 2. Helps you see The Big Picture of the possible problem 1. Faster, more accurate damage assessment 2. Tells you where to place the meter... (first). 3. Catastrophic indoor water damage is much simpler than exterior or forensic investigation, because: 1. Water source is known 2. Moisture nearly always appears cooler (evaporative cooling) 3. Very little weather or solar influence 4. Fewer layers Practical Aspects of Locating & Measuring Moisture in Buildings 14 of 35

15 Part 2 - Measuring moisture content in buildings 1. Exploration: finding and tracking the path of excess moisture 1. A need for speed 2. Hundreds, or thousands of measurements, to form a pattern 2. Tracking changes over time - Drying or wetting 1. Evaluating the rate of change - the slope of the curve 2. Measurements on successive days or weeks 3. Go-No go decisions: To wet to install, or not dry enough to prevent mold 1. A need for reasonable accuracy 2. Repeatability within the range of interest 3. Comparison to credible standard, using credible instrument Practical Aspects of Locating & Measuring Moisture in Buildings 15 of 35

16 Ranges of interest for mold & moisture problems in buildings Below some levels there is almost certainly no problem in a building. Above other levels there is definitely a potential problem: Lumber, plywood & OSB: 12-30% Gypsum board: % Concrete: 2-6% Masonry block: 2-6% Practical Aspects of Locating & Measuring Moisture in Buildings 16 of 35

Equilibrium RH aka: RH meter RH moisture

17 Popular moisture meters Pin-type aka: Resistance-based Penetrating meter Non-penetrating aka: Non-destructive Impedance Radio frequency Capacitance Dielectric Equilibrium RH aka: RH meter RH moisture content Practical Aspects of Locating & Measuring Moisture in Buildings 17 of 35

Less-common moisture measurement techniques

Flooring test Concrete test Speedy tester

moisture Time domain reflectometry aka: TDR

18 Less-common moisture measurement techniques Calcium chloride aka: Vapor emission RMA test Flooring test Concrete test Speedy tester aka: Calcium carbide Soil moisture Sand moisture Time domain reflectometry aka: TDR probe Soil moisture Microwave aka: RF test Limestone moisture Moisture profiler Practical Aspects of Locating & Measuring Moisture in Buildings 18 of 35

19 The best choice depends on: Purpose of the measurement Exact location of the measurement, in 3 dimensions Need for fast scans, vs. accurate and repeatable values The value of recording and reporting the values and their locations Practical Aspects of Locating & Measuring Moisture in Buildings 19 of 35

20 Pin-type moisture meters Practical Aspects of Locating & Measuring Moisture in Buildings 20 of 35

21 Pin-type meters Advantages Much more consistent than non-penetrating meters Lower in cost, with reasonable consistency between same model Acceptable accuracy Limitations Makes two holes, EVERY time! Surface moisture, unless the pins go deep Not consistent between meters from different manufacturers Requires consistent and constant pressure for accuracy Usually measures only WME, not substrate-specific MC Practical Aspects of Locating & Measuring Moisture in Buildings 21 of 35

22 Significant variation, even in homogeneous material 14.5% 15.0% 16.0% 19% 13.5% Practical Aspects of Locating & Measuring Moisture in Buildings 22 of 35

23 Zero reading ( in air alone) not always zero -5.8% +2.0% +6.0% Practical Aspects of Locating & Measuring Moisture in Buildings 23 of 35

24 Out of range (max reading) varies between meters 44% 37% 100% 40% Practical Aspects of Locating & Measuring Moisture in Buildings 24 of 35

25 Non-penetrating moisture meters Practical Aspects of Locating & Measuring Moisture in Buildings 25 of 35

26 Non-penetrating meters Advantages No holes! Much faster for big picture scans Limitations Higher cost than pin meters Many types fooled by steel studs and corner beads Different manufacturers use totally different scales Very few display %MC, usually relative numbers True penetration depth never really clear Results usually more operator-dependant than pin meters Practical Aspects of Locating & Measuring Moisture in Buildings 26 of 35

27 Often fooled by steel studs and corner beads 50 in open air 189 over the corner bead 101 at right of column Practical Aspects of Locating & Measuring Moisture in Buildings 27 of 35

28 Other brands also fooled by steel studs and corner beads 62 over the corner bead 10 at right of column Practical Aspects of Locating & Measuring Moisture in Buildings 28 of 35

29 Technique is critical - Example #1 Intuitive.. But wrong! Correct angle Finger position affects reading Practical Aspects of Locating & Measuring Moisture in Buildings 29 of 35

30 Technique is critical - Example #2- hand pressure No hands: 12% Tilted slightly left: 10% Tilted slightly up: 8% Practical Aspects of Locating & Measuring Moisture in Buildings 30 of 35

31 Moisture Content is not uniform, even in homogeneous materials Important MC differences exist across very small distances Practical Aspects of Locating & Measuring Moisture in Buildings 31 of 35

Key points about moisture readings Most meters display WME, not substrate-specific moisture content Lack of repeatability between instruments demands

important The *exact* location is critical to understanding the meaning of the measurement Error is at least +- 3 or 4% of dry weight Operator technique

32 Key points about moisture readings Most meters display WME, not substrate-specific moisture content Lack of repeatability between instruments demands documentation Make, model and serial number Measurement scale used (WME, or whatever) All can be fooled by surface moisture, and Z-dimension is quite important The *exact* location is critical to understanding the meaning of the measurement Error is at least +- 3 or 4% of dry weight Operator technique Variations between meters Variations in the substrate material Substrate temperature Practical Aspects of Locating & Measuring Moisture in Buildings 32 of 35

Close enough to read the values Practical Aspects of

33 Good practice labels, with photo-based documentation Photo #1 Show the location, and its context Photo #2 Close enough to read the values Practical Aspects of Locating & Measuring Moisture in Buildings 33 of 35

34 Summarizing moisture meters for building investigations Non-penetrating meter probably best for: Perceiving the overall situation quickly Monitoring a known location over time, nondestructively Measurements under ceramic tile or flooring tile (bathrooms & kitchens) Pin-type meters probably best for: More reliable moisture content values Establishing beginning and ending values for drying When it really matters (health, safety or legal liability).. Document the locations as precisely as possible Photos can be comprehensive, and convincing Practical Aspects of Locating & Measuring Moisture in Buildings 34 of 35

Overall Summary IR cameras very useful for locating suspect areas But they only show surface temperatures Suspicions must be confirmed with meters Moisture meters are useful, but have

readings Very clumsy and awkward to document large numbers of readings Photo-based documentation can help reduce limitations of current moisture meters See the preprint for detailed

35 Overall Summary IR cameras very useful for locating suspect areas But they only show surface temperatures Suspicions must be confirmed with meters Moisture meters are useful, but have significant limitations Lack of repeatability between different instruments WME readings are typical ( not substrate-specific MC) Confusion between penetrating and non-penetrating MC readings Very clumsy and awkward to document large numbers of readings Photo-based documentation can help reduce limitations of current moisture meters See the preprint for detailed suggestions for improving moisture meters for more practical use in buildings (eg: a backlit display would be useful!) Practical Aspects of Locating & Measuring Moisture in Buildings 35 of 35

STUCCO FAILURES and REMEDIATION Roger G. Morse AIA

STUCCO FAILURES and REMEDIATION Roger G. Morse AIA Morse Zehnter Associates Rensselaer Technology Park 165 Jordan Road Troy, NY 12180 rgmorse@mzaconsulting.com Florida Environment Hot Humid High ground