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Strategies for prevention of rot, mold, or insect damage in buildings:
What methods will help prevent damage from wood destroying insects in a building? What structural, design, or chemical options are there to prevent insect damage?
Preventing damage by wood destroying insects (termites, carpenter ants, powder post beetles) by good design and by building maintenance is preferred to simple chemical
applications around a property.
Page top photo: those rectangular cracks in wood are a sign of rot, not insect damage, but we often find both insect damage and rot together.
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Nine Approaches to Prevention of Wood Destroying Insect Damage
Architectural design:
to resist wood destroying insect attack: the best wood destroying insect resistant-building design is to
keep wood and other insect-friendly materials at least 8" above ground (some areas permit 6"), provide no protected path for insect entry into the structure (such as behind solid insulation boards)
keep surface water and roof spillage away from the building perimeter. Do not pile up leaves, organic debris, wood piles, or mulch against building walls. Hire a professional to inspect the building, especially at high-risk points.
Termite bait traps:
BAIT TRAPS for TERMITE CONTROL - explains how termite bait traps are used to detect termites near a building; this method avoids use of chemical barriers but requires very reliable, regular inspection as the theory is based on detection (and changing the bait to a poison at that time) rather than prevention of insect attack.
Chemical barrier:
that resists insect attack: is applied around and under the building. Chemical barriers for termites and other wood destroying insects used to work very well, but modern chemicals may be less effective/less durable over time due to changes in pesticides to make these chemicals less of an an environmental hazard.
TERMITE SHIELD Installation describes how and where metallic shields are installed to make it more difficult for insects to enter wood framing from the ground or through the building foundation.
While a termite shield does not absolutely prevent attack by termites nor other wood-destroying insects from the ground, the shield can force termites to build mud tubes around a visible flange making the attack easier to detect.
A termite shield is simply a metal shield is set atop all wood sills, extending an inch or more past the building interior and exterior wall surfaces, bent on an angle downwards to shed water, with exact details specified by a pest control officer and installed during construction.
A termite shield may be effective but remains a risky approach to bug-proofing if the shield is not inspected and if not kept visually accessible on both inside and outside of the buildings for periodic check - a termite mud tube might bypass a metal shield.
Water & moisture control:
It is no surprise that quite often we find that the primary point of attack by carpenter ants or termites on a wood structure is where there is or was a leak that wet wood members.
Even in the case of powder post beetles, where leaks may not be immediately present, a history of high indoor or basement or crawl space moisture levels increase the risk of that attack.
By keeping water away from the building foundation, fixing leaks that send water through the structure, and by keeping indoor humidity at appropriate levels we can reduce the attractiveness of wood and structural members to wood destroying insects, particularly carpenter ants and termites.
Start by a complete and competent inspection of the building to identify existing leaks or moisture problems as well as construction details that invite a leak or moisture issue.
On 2022-01-05 by Marc
- inspector says we have old house beetles - does this photo show them?
Just had old house inspected and the guy says we have old house beetles, there is no moisture in the crawl space, the wood is extremely dry , when you peel back a piece you get powered wood, here are some pictures. I do not see that we have an active infestation of anything. What do you all think.
On 2022-01-06 by Inspectapedia Com Moderator (mod)
@Marc,
I clicked to see the enlarged high-res copy of your photo: all I can see are what look like sap marks.
That is not old house borers nor powder post beetle activity on the upper and lower wood members. But there may be old old house borer or powder post beetle activity in the center of your photo - I need to see more.
Activity is usually apparent as very tiny round holes like those light spots on the darker brown wood in the center of your photo, and when the borers or beetles are acvtive, you'll see, around the holes and often below them, some light colored, very fine wood dust or frass.
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In addition to any citations in the article above, a full list is available on request.
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: info@buildingadvisor.com
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
[3] Jeffrey Hahn, Colleen Cannon, and Mark Ascerno, "Carpenter Ants", University of Minnesota Extension, retrieved 9/19/2012, original source: http://www.extension.umn.edu/distribution/housingandclothing/dk1015.html, copy on file as [Carpenter_Ants_UMinn.pdf]
[4] Paul Probett, Clinton Craig, Blake Probett, "An Introduction to Micro-Drilling Technology for N. Z. Structural Timber Assessment", Incodo Ltd, 4/511 Cameron Rd, Tauranga NZ, article adapted by InspectAPedia with permission, August 2012. Contact the authors by Email: Paul Probett, mail2us@incodo.co.nz , Tel: 027 28 000 36 (Mobile) Website: https://www.incodo.co.nz/ [Copy of this article on file as Microdrilling_Assessment_Incodo.pdf]
Quoting from the Incodo website the company describes its services:
Incodo Forensic Building Pathology:
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.
[5] 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.
[8] Desert Termites, Thomas W. Fuchs, Extension Entomologist, Darrell N. Ueckert, Texas Agricultural Experiment Station, and Bastiaan M. Drees,
Extension Entomologist, Texas Agricultural Extension Service, Texas A&M University System, web search 09/13/2010, original source: http://insects.tamu.edu/extension/bulletins/uc/uc-016.html
[9] Termites - Greenhouse Gases, U.S. EPA, Environmental Protection Agency. Web search 09/11/2010, original source: http://www.epa.gov/ttn/chief/ap42/ch14/final/c14s02.pdf Quoting an interesting passage from this brief document: Termites inhabit many different ecological regions, but they are concentrated primarily in
tropical grasslands and forests. Symbiotic micro-organisms in the digestive tracts of termites
(flagellate protozoa in lower termites and bacteria in higher termites) produce methane (CH4).
Estimates of the contribution to the global budget of CH4 from termites vary widely, from negligible
up to 15 percent.
[10] Truly Nolen Pest Control, Tel: 866-221-4765, is a national franchise of pest control operators in the U.S. Quoting from the company's website: Truly Nolen [has] over 80 offices located in Arizona, California, Florida, Nevada, New Mexico, Texas and Utah. The company services more than 150,000 customers and employs about 1,100 partners, with almost 50 percent service technicians. Domestic franchises are offered throughout the United States. International franchises are also established in over 30 countries.
[11] U.S. EPA. Prevention, Pesticides, and Toxic
Substances. 1997. Re registration eligibility decision:
Diflubenzuron. Pp. 17, 46. www.epa.gov/
pesticides.
[12] U.S. EPA. Office of Prevention, Pesticides and
Toxic Substances. 1994. Pesticide fact sheet:
Hexaflumuron. Washington, D.C.
[13] U.S. EPA. Office of Pesticide Programs. 2003.
Pesticide ecotoxicity database. Unpublished database.
U.S. EPA. Prevention, Pesticides, and Toxic
Substances. 1998. Re registration eligibility
decision: Hydramethylnon. Pp. 16-18, 43.
www.epa.gov/pesticides.
[14] U.S. EPA. Prevention, Pesticides and Toxic Substances.
Undated. New chemical New chemical fact sheet:
Noviflumuron. Washington, D.C.
[15] "Protecting Your Home from Subterranean Termite Damage", Journal of Pesticide Reform, Fall 2004, V 24 No. 3, - 6-7, Northwest Coalition for Alternatives to Pesticides/NCAP, POB 1393, Eugene OR, 97440 541-344-5044 www.pesticide.org: Web search 09/11/2010: http://www.hipspro.com/pubs/subterraneantermites.pdf
This document discusses alternatives for termite protection including reducing the attractiveness of the structure to termites (get wood away from the building, fix leaks), use of 16-grit sand (diameter 0.06 - 0.1 in) as a termite barrier 18" wide x 3" deep in crawl areas, or stainless steel mesh for the same purpose under foundations and slabs, boric acid, Diflubenzuron (insect growth regulator, risk genetic damage, EPA classed as carcinogen), Hexaflumuron (insect growth regulator, EPA didn't ID health concerns, waived some testing, partly because of anticipated very low risk of human exposure), Hydramethylnon (stomach toxicant, EPA: Carcinogen, highly toxic to fish), Noviflumuron (chemically similar to hexaflumuron), can cause anemia, EPA didn't ID other health hazards, some testing requirements waived, moderately toxic to fish).
[16] "House Eating Fungus"Meruliporia incrassata (also called "Poria" the house eating fungus) in the U.S. or Serpula lacrymans in Europe) can cause severe structural damage. Evidence of hidden "poria" may be found by expert inspection methods which include tracing sources and paths of probable Building
leaks and moisture traps. Further, careful indoor particle sampling methods can often permit the presence of this mold to be identified in the laboratory.
[17] Pesticides Contaminate House [PDF] - news article about improperly applied pesticide chemicals and building contamination
[18] Termite Damage Case Study#1 - exterior clues predicted insect damage; interior access was limited but certain clear clues led right to the damage
as well as an attempted cover-up of termite damage below a "repaired" wooden floor. The real evidence was in the driveway. [in process]
[19] Termite Damage Case Study#2 - very limited visual access inside a building made this inspection for structural damage tough. Outside
conditions suggested a risk of water entry and insect attack. Inside the house had mysteriously sloping floors - sloping in every direction.
There were few indications of ongoing building movement to explain the sloping. Perseverance led to finding severe termite damage at the
building sills. [in process]
[20] Wikipedia Web: https://www.wikipedia.org/ provided background information about some topics discussed at this website provided this citation is also found in the same article along with a " retrieved on" date. NOTE: because Wikipedia entries are fluid and can be amended in real time, we cite the retrieval date of Wikipedia citations and we do not assert that the information found there is necessarily authoritative.
Termites, Wikipedia web search 09/11/2010, original source: http://en.wikipedia.org/wiki/Termite provided some information about termite size.
[22] Panshin, A. J. and Carl de Zeeuw. Textbook of Wood Technology, 1980, NY: McGraw-Hill.
[23] Story, Keith O. Approaches to Pest Management in Museums, 1985, Washington D.C.: Smithsonian Institution.
[24] University of Wisconsin Dept. of Entymology, "Insect ID - wood attacking insects", retrieved 10/25/2012, original source http://www.entomology.wisc.edu/insectid/wood-attk.php
In addition to citations & references found in this article, see the research citations given at the end of the related articles found at our suggested
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