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WIND TURBINES & LIGHTNING
WIND WASHING INSULATION At EAVES
WINDOWS & DOORS, Age, Types
WINTERIZE A BUILDING
WOOD STRUCTURE ASSESSMENT
Test methods for determining the soundness of wood structural members: This article series surveys methods used to test & evaluate the structural integrity of wood-framed buildings where focus is on the condition of structural wood posts, beams and other framing members. We discuss the problems surrounding hidden rot or decay, the presence or absence of moisture or other instrument-detectable clues, and the problem of subjective decisions to replace or not-replace suspect wood structural members. Page top image of micro-drilling, USDA FPL .
This article compares using micro-drilling with other methods to screen both standing trees and wood structural elements for hidden damage.
The original authors, Probett et als., propose a technique to provide objective pass-fail data on the condition of in-situ but suspect structural wood using micro drilling to examine wood density. This service uses timber resistance drill technology to profile variations in timber density associated with timber decay. The work is done on site and the results are instant.
This technology is objective and evidential in nature and provides assessment as to whether wood is significantly decayed, suspect or suitable for retention.
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Paul Probett, Clinton Craig, Blake Probett, Incodo Forensic Building Specialists 
This article series on methods for assessing structural wood rot & damage is adapted & expanded from the author's "An Introduction to Micro-Drilling Technology for N. Z. Structural Timber Assessment" and is used with permission. We [DF] have added comments, some illustrations, and additional article citations.
At the references section we include a link to the original article as well as contact information for the authors and Incodo Ltd., a Tauranga, New Zealand forensic engineering firm.
The original authors' article without the expanded discussion added here can be seen at An Introduction to Micro-Drilling Technology for N. Z. Structural Timber Assessment.
Additional comments, illustrations, and technical citations addressing wood structure testing technologies have been added. We and the original authors invite and will reply to reader questions and comments using the comments box found at the end of this article. Initial technical review completed 8/6/201
[Click to enlarge any image or illustration]
A variety of tools and methods for assessing the condition of standing trees as well as the structural integrity of in-use wood timbers & beams has been in use for decades.
Several methods for obtaining drill samples or core samples from standing trees have long been in use by agencies such as the U.S. Forest Service and agencies in other parts of the world as part of evaluating the condition of standing timber and forests.  In addition a variety of other methods such as ultrasound, stress waves, electrical resistance testing, mechanical coring or boring, visual inspection, and even a simple plastic hammer have been used to evaluate possible decay or insect damage in both trees and other exposed, accessible wood structural elements.
Methods used initially to evaluate standing timbers were quite naturally expanded to permit assessment of the structural integrity and condition of key wood structural members that are completely exposed and thus readily accessible, such as timber-constructed bridges, bridge pilings, telephone poles, railroad ties, as well as engineered lumber such as block-laminated timbers. and 
The presence of those tools and methods for testing exposed timbers suggested possible applications in the evaluation of buildings and other structures in which their structural wood members may be partly or even completely hidden by finish materials.
More recently, Bohumil Kasal & Thomas Tannert have led research on the design of microdrilling methods and on the reliability of such tests in predicting the actual bending or breaking strength of structural wood members.
It was Kasal who developed recent technology of taking micro specimens of wood that in turn might be used to obtain direct measurements of the modulus of elasticity and strength of wood (in the area tested).
A direct measurement of the tension properties of wood along the wood fibers permits bending strength evaluation - important because bending strength is a key property in evaluating the structural integrity of a wood beam. Kasal's significant observation was that
Here, in expansion of an original article by Probett et als , here we discuss the range of structural wood beam or timber assessment methods where wood beams, timbers, or other structural members are used in buildings and where there is known or suspected risk of structural damage from leaks, decay by wood rotting fungi, or damage by wood destroying insects.
Because Probett et als propose and discuss the applicability of micro-drilling test methods for assessing wood structural members in-situ with or without having to perform more extensive demolition to actually expose the members, special attention is given to this method of structural assessment of wood, including Probett et als' test protocol and progress in evaluating the efficacy of this method.
That 2005 study provides important independent experience and assessment of the micro-drilling approach to structural wood testing.
As you will read in our inserted opinions and warning remarks in the article below, wood testing equipment should not be used by itself to form conclusions about a structure. Excerpting from the Brashaw micro-drilling study conclusions:
Why perform in-situ timber or wood structural member assessment?
In situ Timber Assessment Compared with Other Current Bases for Wood Structural Member Assessment
These conditions result in two significant error risks:
In situ Timber Assessment Impact on Government Departments and Local Authorities
Current In-situ Wood Beam, Timber, or other Wood Framing Member Structural Condition Assessment Methods
Current choices for assessing the structural integrity of wood timbers, beams, or other framing members include the following:
Each of these approaches to detecting wood beam rot and assessing its extent and its impact on the condition and serviceability of the wood member being examined is discussed and compared in the article segments listed above.
In 2013 Probett et als. presented an update on the status of micro-drilling for wood timber assessment at the U.S. FPL Wisconsin conference: 18th International Nondestructive Testing and Evaluation of Wood Symposium, as we cite below. Significant in Mr. Probett's remarks is
Bob Monk, USDA Forest Service, discussed the use of various types of equipment capable of detecting decay in standing trees - the epitome of in-situ testing. Monk described and tested an extensive list of tools and methods for assessing the condition of trees, possibly also used for structural wood member evaluation. Monk's USDA article expands upon the types of options and test instrument applications discussed here. The following table of tree decay detection equipment is adapted from Mr. Monk's USDA article  - DF
Continue reading this article series at WOOD BEAM VISUAL INSPECTION
Article series contents
Continue reading at STRUCTURAL DAMAGE PROBING
and see TIMBER FRAMING, ROT where we describe the relationship between construction details and the occurrence of structural rot in timber frame buildings.
Also see our insect damage & wood-destroying insect type identification articles beginning at INSECT INFESTATION / DAMAGE or select a topic from the More Reading links shown below.
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