POST a QUESTION or READ FAQs about methods used in testing structural wood members for damage or decay & the role of micro-drilling tests for in-situ evaluation of structural wood beams, timbers, or other framing members in buildings..
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Use if micobiological assessment - expertise in wood-destroying fungi - in determining the soundness of wood structural members.
This article discusses the role of mycology and microbiology in detecting & assessing damage to wood beams, joists, posts, studs, rafters etc. Mycology can provide key information about the conditions that invite wood destroying fungi (molds such as Meruliporia incrassata - the "house eating fungus"), as well as assisting in recognition of mold infection or contamination in structures. Page top photograph: yellow Meruliporia incrassata fungal growth on an indoor wood surface.
This article series describes the various 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.
Microbiologist / Mycologist Methods for Wood Structural Member Assessment
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.
[Click to enlarge any image or illustration]
Using microbiological assessment requires an expert, mateiral samples, time, cost. Often we use microbiological assessment as an additional method to aid a visual assessment of rot damage to a structure.
Scope = Microscopic to sample size (minor usage in deciding actual replacement, adds genuine weight to reports). Not in situ assessment
Note: in our opinion, microbiologists and aerobiologists can provide a useful supporting role in assessing building conditions (mold or other IAQ hazards) including providing additional screening for evidence of hidden but active wood destroying fungi.
Few microbiologists nor mycologists have the requisite familiarity with building science and construction failures to serve as a primary building screener for hidden damage.
But those sciences can add important depth of understanding to field observations by others. For example, a mycologist can explain that if we see "mushrooms" growing out of wood framing members, there is almost certainly substantial hidden rot damage that merits further invasive inspection. Similarly, the identification of some mold genera/species by spore trap or dust sampling can yield important insights into building conditions and the risk of hidden damage.
For example we have found high levels of Meruliporia incrassata. spores in building environmental samples at levels indicating a nearby infection of this wood destroying fungus. But unless the work is conducted by someone who is also expert in building science and who is also familiar with construction methods and construction inspection methods, such assessments are likely to be unreliable.
See MERULIPORIA MOLD PHOTOS for details. Photo, above of Meruliporia incrassata and other fungal materials - Daniel Friedman, InspectAPedia lab.
Shown in the photograph a left, the black cosmetic mold seen on this floor joist is not a wood destroying fungus.
See BLACK MOLD, HARMLESS for a discussion of the visual recognition of harmless black molds found on framing lumber.
In our view, building "testing" by collecting surface, air, or dust samples for lab analysis, while they can considerably expand the scope of a building assessment beyond "microscopic sample size", are of questionable accuracy unless there is accompanying expert visual inspection and history taking.. - DF
Note: Above information is copyright, commercially sensitive and is yet to be peer reviewed. It is not to be copied or circulated without the express and written permission of Incodo Limited. Adapted here by InspectaPedia.com, with permission from Incodo 8/5/2012, technical review is in process.
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The Forensic Building Pathology division provides evidence in report form to government agencies, consultancy firms, lawyers and others, when truly independent analysis based on comprehensive testing is required. Incodo arguably has the largest, most up-to-date and comprehensive range of building investigation equipment available and has developed unique methodologies particularly in the field of non-destructive testing for leaking structures.
Incodo In situ Timber Assessment:
The in-situ Timber Assessment division provides a service whereby technicians use state-of-the-art 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. The technology has particular application in locating and assessing hidden decay.
 Thomas Tannert, Andreas Muller, Mareike Vogel, "Applications and limitations of NDT: a timber bridge case study", NDTCE’09, Non-Destructive Testing in Civil Engineering
Nantes, France, June 30th – July 3rd, 2009, web search 8/3/2012, original source: http://www.ndt.net/article/ndtce2009/papers/144.pdf [copy on file as Tannert_Timber_Test_144.pdf] Abstract The applications and limitations of different non-destructive and semi-destructive
techniques to evaluate the structural integrity of timber members in a pedestrian bridge are
presented as a case study. Sophisticated assessment tools are required to detect hidden
damages in timber structures: for example stress-wave techniques are used to evaluate the
modulus of elasticity of bending members and resistance to drilling is used to gain knowledge
of areas of changed density due to insect or moisture induced damages. Reliably relating the
gathered data to the structural integrity of the structure is a complex issue. Bending members
and connection details of a decommissioned timber bridge were evaluated using non
destructive assessment tools. Eventually these parts were tested destructively to assess their
remaining modulus of elasticity and load bearing capacity. The need for improvements in the
current practice is highlighted by comparing the results from the non-destructive, semidestructive
and destructive tests.
 Bohumil Kasal, Thomas Tannert, "RILEM Technical Committee on In Situ Assessment of Structural Timber", Bohumil Kasal et al., 2010, Advanced Materials Research, 133-134, 271, Abstract:
Timber is an intriguing structural material and the only one that is truly renewable. Being biodegradable, hygroscopic and non-isotropic, it presents special challenges when assessing its integrity in structures. The presented paper outlines the major issues related to in-situ evaluation of structural timber and summarizes the work of the RILEM Technical Committee 215-AST “In-situ assessment of structural timber”. The committee was established in 2005 to bring together leading scientists and practitioners in the field of evaluation of timber in existing structures. Timber structures have been investigated for decades using numerous techniques that have been either developed specifically for the material or were transferred from other fields of investigation. A state-of-the-art report describing existing and emerging technologies and methods was prepared by the RILEM committee. The report describes the principles, the applications and the limitations of major evaluation techniques for in-situ assessment of timber. A brief discussion of codes standards and future research needs shows that much needs to be done in this area. As a present activity, harmonized test procedure recommendations are being prepared that will provide the engineering community with valuable guidance when evaluating timber structures.
 Bohumil Kasal & Thomas Tannert (Editors), In Situ Assessment of Structural Timber, ISBN 978-94-007-0559-3, Rilem 2010
 Bohumil Kasal, Tension Micro Specimens,
In Situ Assessment of Structural Timber
RILEM State of the Art Reports, 2011, Volume 7, 75-80, DOI: 10.1007/978-94-007-0560-9_8, [excepts chapter 7 on file: Tension Micro-Specimens, as Kasal_Testing.pdf]
The principle of this method is extracting triangular specimens (about 5 mm equal-sides triangle) along the length of the member. Small-kerf circular saw with a fixture attached to the surface of the member is used to extract the specimens. Specimens are then glued to the test blocks and tested in tension. The method gives direct values of tensile modulus of elasticity and strength for clear wood. The values are local and pertain to the tested area and surface.
[From chapter 7.1 Background: This method was developed by Kasal and is based on direct measurement of tension properties along fibers. Bending strength evaluation is an important aspect of in situ evaluation of timber members as it is one of the predominant modes of loading, but estimates of the bending properties in situ can present a challenge. With information on the member's tensile properties, bending strength estimates can be made; tensile strength has been related to bending strength and is considered to be approximately equal. Tensile properties have a poor correlation with compression properties therefore tensile strength can not be estimated using information attained with the core drilling technique. Specimens can however be extracted to evaluate the tensile properties of in situ members with the technique described in the following sections....']
[Also] Kasal B, Anthony R: Advances in in-situ evaluation of timber structures. Progress in Structural Eng and Materials. 6(2):94-103, 2004.
 Thomas Tannert, Andreas Müller, Mareike Vogel, "in-situ assessment, hot spots, moisture content, block-laminated timber", ICTB 2010, Bern University of Applied Sciences. ISBN 978 8251 926805, in-situ assessment, hot spots, moisture content, block laminated timber,
Abstract: Timber has been a structural material for bridges for centuries and numerous examples throughout the world demonstrate its durability. But timber is biodegradable and hygroscopic and regular inspections are recommended to determine the condition of the structure. This paper reports on the structural health monitoring of timber bridges in general and the long term moisture measurement inside block-laminated timber elements of several traffic bridges in specific. Presently there is no reported scientific information available on the long-term moisture behaviour and the resulting moisture induced stresses and dimensional changes of block-laminated timber elements. The paper reports on the monitoring of the moisture content of a block-laminated timber bridge.
[References 7-13 below are cited from this document]
 Wilkinson K, Thambiratnam D, Ferreira L. Non Destructive Testing of Timber Bridge Girders. In Proceedings Int. Conf. on Structural Condition Assessment, Monitoring and Improvement, Perth, Australia, 2005.
 Kasal B, Anthony R: Advances in in-situ evaluation of timber structures. Progress in Structural Eng and Materials. 6(2):94-103, 2004.
 Gerold M. Bloc-Glued Laminated decks for timber bridges. Structural engineering international, 12(3): 214–217, 2002.
 Graham T. Overview of non-destructive evaluation technologies. In Proceedings of the Nondestructive Evaluation of Aging Bridges and Highways, Ed by S. Chose, 1995.
 Duwadi SR, Ritter MA. An Overview of the Wood in Transportation Program in the United States, In Proceedings 5th World Conference on Timber Engineering, Montreux, Switzerland, 1998.
 Rinn F, Schweingruber FH, Schär E. Resistograph and X-Ray Density Charts of Wood. Comparative Evaluation of Drill resistance Profiles and X-Ray Density Charts of Different Wood Species. Holzforschung 50:303-311, 1996.
 Brashaw B, Vatalaro RJ, Wacker JP and RJ Ross. Condition Assessment of Timber Bridges: 1. Evaluation of a Micro-Drilling Tool. Gen. Tech. Rep. FPL-GTR-159. Forest Products Laboratory Madison, WI. 2005.
Simpson W. Drying and Control of Moisture Content and Dimensional Changes. Chapter 12, Wood handbook - wood as an engineering material. General Technical Report FPL–GTR– 113. Forest Products Laboratory, WI, 1999.
 "Fractometer Print Manual", IML
Instrumenta Mechanik Labor System GmbH
Großer Stadtacker 2
69168 Wiesloch • Germany, 02-2008, web search 8/4/12, original source: http://www.imlusa.com/Fractometer_Print_eng_web_A4.pdf [Copy on file as Fractometer_Print_eng.pdf]
 Bob Monk, "Evaluation of Decay Detection Equipment in Standing Trees", USDA Forest Service, web search 8/4/12, original source http://www.fs.fed.us/eng/techdev/IM/tree_decay/tree_decay_detect_equip.shtml [Copy on file as Monk_Tree_Deday_Detection.pdf] Introduction - quoting: A project was proposed to test and compare several of the devices that are able, to some
degree, to detect decay in trees. Decay in trees is directly related to the hazards that they
present. However, detection of decay does not necessarily mean that a tree is hazardous. The
identified devices can be used to determine what decay is present. It is still necessary to use
professional experience and sound judgment to decide if a tree actually poses a hazard.
General guides or "rules of thumb" can also be used, such as Guidance notes from the
Minnesota Department of Natural Resources and the USDA Forest Service, 1996 that suggests
a 25 mm ring of sound wood is required for every 150 mm of stem diameter at any point on
the stem. If the proportion of decayed wood to sound wood exceeds this level then action may
need to be taken to minimize the hazard posed by the tree (Lawday and Hodges, 2000). [Additional selected citations from this article are below]
[16a] Larsson, B.; Bengtsson, B.; and Gustafsson, M. 2004. Nondestructive Detection of Decay in
Living Trees. Tree Physiology. 24: 853-858
[16b] Moore, W. 1999. The Combined Use of the Resistograph and the Shigometer for the Accurate
Mapping and Diagnosis of the Internal Condition of woody Support Organs of Trees.
Arboriculture Journal. 23: 273-287
[16c] Nicolotti, G.; Socco, L.V.; Martinis, R.; Godio, A.; and Sambuelli, L. 2003. Application and
Comparison of Three Tomographic Techniques for Detection of Decay in Trees. Journal of
Arboriculture. 29(2): 66-77
[16d] Seavey, R.; and Larson, T. 2002. Inspection of Timber Bridges. Minnesota Department of
Transportation Technical Report MN/RC-2002-34. St. Paul, MN. 43 p.
[16e] Wang, X.; Divos, F.; Pilon, C.; Brashaw, B.K.; Ross, R.J.; and Pellerin, R.F. 2004. Assessment
of Decay in Standing Timber Using Stress Wave Timing Nondestructive Evaluation Tools: A
Guide for Use and Interpretation. Gen. Tech. Rep. FPL-GTR-147. Madison, WI: U.S.
Department of Agriculture, Forest Service, Forest Products Laboratory. 11 p.
 Pilodyn Wood Tester, USA / Canadian Source: Intech-NDE, 6211 Roper Road
T6B 3G6, Tel: 1 888-576-7756 or Intech-NDE, 140 - 8851 Beckwith Road
Richmond, B.C., Tel: 1 800-677-8884, or USA Tel: 800-297-3208, Website: http://www.intechnde.com, web search 8/4/12, original source: http://www.corvib.com/pilodyn/ Quoting:
Pilodyn is an easy-to-use wood testing instrument which is suitable for trees, railway ties and utility poles. The Pilodyn wood tester (Hylec Controls) is described by and currently available in North America from InTech/NDE U.S. Tel: 905-716-5604 / 800-297-3208, or Email: email@example.com
 Pilodyn Wood Tester, Hylec Controls, available in Australia from Ferret http://www.ferret.com.au/n/Pilodyn-wood-density-meter-from-Hylec-n852069 - Quoting: Pilodyn, available from Hylec Controls , was developed to determine the density and strength of dead and living wood. Invisible soft rot can be detected rapidly and objectively in an easy non-destructiveway and the reduction in strength associated with it can be determined. This can be of vital importance in the case of wooden playground structures,climbing frames and telephone masts.
With PILODYN 6J Forestversion the density of the wood is determined on living trees. The damage is so little that the tree suffers no harm and the testing method is regarded as non-destructive.
Testing procedure: The testing procedure is very simple: The tester is loaded with the ramrod and then pressed firmly onto the tet surface. The impact pin is shot into the wood by pressing the trigger cover. The depth of penetrationcan be read straightaway in mm on the scale mounted on the tester.
Typical applications of the Pilodon:
Testing the stability of wooden structures on playgrounds, detection of soft rot
Testing the strength on wooden telephone masts, detection of soft rot
When thinning out: sorting out trees with undesirable density of the wood
Early detection of diseases: periodic measurement detects unnatural changes in the wood density
Comparison of the location-dependent density to determine the optimal location for the respective tree species
Establishing productivity with respect to density for the same tree species and similar location properties for culture purposes
Testing and sorting of cut wood into timber classes
 Brashaw, Brian K.; Vatalaro, Robert J.; Wacker, James P.; Ross, Robert J. 2005. "Condition Assessment of Timber Bridges: 1. Evaluation of a Micro-Drilling Resistance Tool" Gen. Tech. Rep. FPL-GTR-159. Madison, WI: U.S. Department of Agriculture, Forest Service, Forest Products Laboratory. 8 p., web search 8/5/2012, original source: http://www.fpl.fs.fed.us/documnts/fplgtr/fpl_gtr159.pdf [copy on file as Micro_Drill_Study_USDA_fpl_gtr159.pdf] This publication is also available from the U.S. FPL at www.fpl.fs.fed.us
Abstract: The research presented in this report was conducted to evaluate the accuracy and reliability of a commercially available micro-drilling resistance device, the IML RESI F300-S (Instrument Mechanic Labor, Inc., Kennesaw, Georgia), in locating deteriorated areas in timber bridge members. The device records drilling resistance as a function of drilling depth, which allows the operator to assess the location of deterioration in the member cross section. Bridge components containing different levels of natural decay were used as test specimens in this study. The IML RESI F300-S was first used to assess decay in the timber bridge specimens. The specimens were then sawn along their length into slabs to expose their interior condition. The interior faces of these slabs were inspected visually and with a stress-wave probe to confirm if deterioration was present. On the basis of these tests, we conclude that this micro-drilling device accurately determines if deterioration is present at the point at which the test is performed.
Keywords: timber, bridges, inspection, drilling resistance, nondestructive evaluation
Excerpt from the study's conclusions: Based on our tests, we offer the following comments about the accuracy of using the IML RESI F300-S for locating deterioration in bridge timbers:
1. The tool is accurate at determining the presence of decay in timber bridge specimens. However, these data are limited to the drilling location.
2. The tool can precisely locate an internal defect (decay pocket, check, or split) within the member’s cross section. This can be advantageous for condition assessment and load rating purposes.
3. Decay indices were developed for Douglas-fir timbers
as follows: sound, >25% resistance; moderate decay, 10–25%; and advanced or severe decay, 0–10%.
One drawback is that multiple, time-consuming drilling would be required to map the area and extent of the decay in the other plane. Another possible drawback is the potential to spread the decay to sound areas within a timber or to sound timbers by multiple use of a contaminated drill bit. Routine cleaning of drill bits, or replacement with a new one, would greatly reduce this potential drawback.
It is crucial to use this or any nondestructive testing tool or device as part of a comprehensive condition assessment. Such an assessment should incorporate an in-depth visual inspection, knowledge of prior use of the structure, and a working knowledge of fundamental engineering properties of structural wood products. This technique, when used in concert with visual and ultrasound techniques, would provide a very accurate description of the condition of timbers.
 Brashaw, B.K.; Vatalaro, R.J.; Erickson, J.R.; Forsman, J.W.; Ross, R.J. 2004. Final Report: A Study of Technologies to Locate Decayed Timber Bridge Members. Project No. 187-6456, NRRI/TR-2004-06. Duluth, MN: UM-Duluth, Natural Resources Research Institute.
 Brashaw, B.K.; Vatalaro, R.J.; Ross, R.J.; Wacker, J.P. 2005. Condition Assessment of Timber Bridges:
2. Evaluation of Several Commercially Available Stress Wave/Ultrasonic Tools. Gen. Tech. Rep. FPL-GTR-160. Madison, WI: USDA Forest Service, Forest Products Laboratory.
 Troltech GMBH & Co. KG. Deutchland, Grebbener Str. 7, D-52525 Heinsberg, Deutchland, produces the Trotec T2000, Tel: 02452 962-450, International: +49 2452 962-450, Email: firstname.lastname@example.org, Website: http://www.trotec.de/, Web page for the Troltec T2000: http://www.trotec.de/en/product-catalog/measuring-instruments/multi-function/t2000/
 Paul Probett, Incodo, Ltd., "Thermal Imaging and Building Surveying / Inspection" 2008, Incodo Ltd, 4/511 Cameron Rd, Tauranga NZ, article adapted by InspectAPedia with permission, August 2012. Contact the authors by Email: Paul Probett, email@example.com , Tel: 027 28 000 36 (Mobile) Website: http://incodo.co.nz/ [Copy of this article on file as Thermal Imaging NDT Presentation 2008.ppt ]
Steve Bliss's Building Advisor at buildingadvisor.com helps homeowners & contractors plan & complete successful building & remodeling projects: buying land, site work, building design, cost estimating, materials & components, & project management through complete construction. Email: firstname.lastname@example.org
Steven Bliss served as editorial director and co-publisher of The Journal of Light Construction for 16 years and previously as building technology editor for Progressive Builder and Solar Age magazines. He worked in the building trades as a carpenter and design/build contractor for more than ten years and holds a masters degree from the Harvard Graduate School of Education.
Excerpts from his recent book, Best Practices Guide to Residential Construction, Wiley (November 18, 2005) ISBN-10: 0471648361, ISBN-13: 978-0471648369, appear throughout this website, with permission and courtesy of Wiley & Sons. Best Practices Guide is available from the publisher, J. Wiley & Sons, and also at Amazon.com
Home Inspection Education Home Study Courses - ASHI@Home Training 10-course program. 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.
The Home Reference Book, a reference & inspection report product for building owners & inspectors. 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.
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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.
The Horizon Software System manages business operations,scheduling, & inspection report writing using Carson Dunlop's knowledge base & color images. The Horizon system runs on always-available cloud-based software for office computers, laptops, tablets, iPad, Android, & other smartphones.
Allen, Edward and Joseph Iano. Fundamentals of Building Construction: Fourth Edition. Hoboken: John Wiley & Sons, 2004. pg. 91 [LVL lumber]
APA - The Engineered Wood Association, 7011 So. 19th St., PO Box 11700, Tacoma WA 98411-0700, Tel: 253-565-7265. APA provides an HDO/MDO Plywood Product Guide that offers details about these products., provides an HDO/MDO Plywood Product Guide that offers details about these products. Product support help desk: 253-620-7400. Email the APA at email@example.com. Web search 09/13/2010, original source: http://www.pacificwoodlaminates.com/img/PDFs/PlywoodGuide.pdf
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.
The Home Reference Book - the Encyclopedia of Homes, Carson Dunlop & Associates, Toronto, Ontario, 25th Ed., 2012, $69.00 U.S., 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: Carson Dunlop Associates offers InspectAPedia readers in the U.S.A. a ten percent discount on any number of copies of the Home Reference Book purchased as a single order. Just enter HRBUS10 in the order payment page "Promo/Redemption" space.