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Fiberboard insulating board or IB sheathed wall bracing:
Where non-structural exterior wall sheathing is used in construction wind bracing is required.
This article series discusses insulating sheathing board products or IB, fibreboard sheathing, and similar products. We also discuss flood damage and mold damage on fiberboard insulating products and building sheathing products such as Homasote, Celotex, and Masonite insulating board sheathing.
Add Structural Support Against Racking or Wind Damage?
Watch out: during new construction or during repair and renovation work on flood or hurricane damaged buildings, where IB or fiberboard sheathing was used as original sheathing on a building's exterior you should inspect the building wall corners for wood or metal bracing that is intended to protect the structure from leaning or racking during high winds.
Wind bracing may have been installed originally as let-in diagonal wood braces (see our photo), by cut in metal bracing, or by use of solid plywood sheathing at the building corners and at other key locations.
Updating the structure to modern strength and wind resistance by bracing may be necessary if your building lacks wind bracing. This might be accomplished by any of the following means.
Diagonal bracing as we describe below is installed to prevent racking of frame-built structures that are sheathed with non-structural materials such as fiberboard, insulating board, or foam board.
Use of wood or metal diagonal bracing at corners or other walls
Traditional wood let-in braced framing technique notches the wall studs to permit nailing in place of diagnonal braces at the building wall corners.
Braces typically are installed from the top plate to the sill plate on a diagonal, and are nailed to the plates and to the studs they intersect.
The diagonal let-in bracing shown in my photo was installed on the outside of the building stud wall at the time of original construction. This example shows a home that was sheathed using gypsum board on the home's exterior.
But this same techinque can work with let-in bracing as a retrofit installation on the wall interior. Wood diagonal bracing was traditionally installed using a 2x4 along the diagonal but a 1x4 may also be permitted, thus reducing the necessary depth of the cutout notch.
Metal diagonal bracing at corners or other walls
Metal diagonal bracing is still easier to install, and is easy to add on an exposed exterior wall frame or on exposed stud wall framing from the interior side of a building exerior wall.
There are several types of metal strapping used for diagonal bracing, of which the traditional T-shape was most familiar to older carpenters.
Two other profiles, flat-strapping and L-shaped strapping are also used for diagonal bracing at wall corners. Flat strapping such as Simpson Strong-Tie's WB product is installed without any requirement for saw cuts or notching, but because it works only in tension, not in compression, it is installed in pairs.
The T-shaped metal strapping is nailed to the top and bottom wall plates and to studs in between along its diagonal, similarly to the wood bracing shown in our photograph.
But instead of having to cut and chisel out a deep and wide notch for the 1x4 or more traditionally 2x4 diagonal brace, the installer simply runs her circular saw along a chalk line snapped along the desired diagonal, making a single cut. The base of the Tee slips into the saw cut.
[Click to enlarge any image]
Use of plywood or OSB sheathing inside at wall corners
With this approach there will remain a decision about furring out other studs or double-layering drywall or as I prefer, coating the plywood with a joint compound veneer before painting, then of course taping all joints to produce a smooth interior wall.
OSB sheathing is commonly-used at the corners and at other strategic locations of the wall exterior in new construction.
If you decide to use structural sheathing on the building interior walls during a flood-damage repair job, plywood, particularly AC plywood with the "A" or smooth side facing the room interior will make subsequent wall finishing and painting easier.
Watch out: Before choosing a metal strapping product for wall bracing check its specifications against what is required by local building codes where you live. Holladay, in an excellent Fine Homebuilding article on shear bracing points out that these products vary in strength, purpose, and acceptability.
You'll want to confirm design alternatives and your choice of wall bracing methods with a structural engineer to obtain a sign-off, but there are alternatives once you've removed moldy drywall, cleaned the wall cavities and sanitized them.
Other suggstions for flood restoration including at brick veneer walls over fiberboard sheathing
Insulation retrofits: Some of our readers have re-insulated wall cavities using a combination of styrofoam cut to fit, foam insulation, and fiberglass.
We presently are working on adding photographs and discussion of that work here in this article. I think sticking fiberglass or any other water-vulnerable insulation back into a wall cavity that is likely to be exposed to future flooding is a bad idea.
Future flood resistance: I'm really glad to see you discussing water-resistant restoration material choices. I am concerned about some Louisiana flood restoration work being done that will be damaged again by the next flood and would prefer that owners, contractors, and insurance companies discuss use of materials and methods that may reduce the cost of damage from the next inundation.
Watch outfor hidden mold and moisture damage in walls or ceilings above the actual flood high-water line. Homes that sat for more than 24-48 hours in wet and high humidity are at high risk of hidden mold damage in upper walls and ceiling cavities.
Simply running a dehumidifier or two along with fans will not "extract" water from the cavities of a flooded building and if not started soon enough it may not have prevented extensive but hidden mold contamination higher in the building.
A few strategic test cuts into those areas are worthwhile. Inspect the cavity side of drywall for visible mold. It's much less costly to do this repair now than to have to return to a "restored" flood-damaged home next year to rip out all of that new work to remove a just-discovered harmful mold reservoir in the building.
Watch out for leaving unsafe electrical devices in a flooded building: Be sure that you insist on review and qualification or probably replacement of electrical devices that were flooded in these walls, such as receptacles and splices.
Research on Structural Support & Shear Bracing Where Fiberboard Panels are in Use
Holladay, Martin, "4 Options for Shear Bracing Foam-Sheathed Walls", Fine Homebuilding, The Taunton Press, Inc.
63 South Main St., PO Box 5506
Newtown, CT 06470-5506 USA
, No. 220, retrieved 2016/09/28, original source: http://www.finehomebuilding.com/2011/05/19/4-options-for-shear-bracing-foam-sheathed-walls
Luxford, Ronald Floyd, RIGIDITY AND STRENGTH OF FRAME WALLS SHEATHED WITH FIBERBOARD. Madison, Wis. [PDF] US Dept. of Agriculture, Forest Service, Forest Products Laboratory, 1957 No. 1151 retrieved 2017/07/30, original source: http://ir.library.oregonstate.edu/xmlui/bitstream/handle/1957/1136/FPL_1151ocr_rev.pdf?sequence=1
Simpson Strong Tie, 20-Gauge 14 Ft. 2 In. Wall Bracing, Model RCWB14, Simpson Strong-Tie Company Inc., Tel: (800) 999-5099, Website: https://www2.strongtie.com
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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
John Cranor is an ASHI member and a home inspector (The House Whisperer) is located in Glen Allen, VA 23060. He is also a contributor to InspectApedia.com in several technical areas such as plumbing and appliances (dryer vents). Contact Mr. Cranor at 804-747-7747 or by Email: email@example.com
Celotex Corporation, headquartered in Tampa, FL, is a national manufacturer of residential and commercial building materials. www.celotex.com 800-CELOTEX
Douglas Leen, Petersburg AK 99833, contributed the photograph of insulating board scraps from roof insulation removed from a building. Dr. Leen provides such a wide range of services, collectables, and historical information about the Northwest that a succinct description is difficult: flying dentist goes anywhere, antique forestry posters, historic campers, the tugboat Katahdin, in Alaska, Washington, and Wyoming. Mr. Leen can be contacted at firstname.lastname@example.org or at 907-518-0335
American Plywood Association, APA, "Portland Manufacturing Company, No. 1, a series of monographs on the history of plywood manufacturing",Plywood Pioneers Association, 31 March, 1967, apawood.org 253-620-7400 APAWood.org
Georgia Pacific: information about DensGlas gypsum board building sheathing can be found at the company's website at gp.com/build/product.aspx?pid=4674
Homasote Co., 932 Lower Ferry Road,
West Trenton, New Jersey 08628-024,
U.S.A. 800-257-9491 homasote.com
"Hurricane Damage to Residential Structures: Risk and Mitigation", Jon K. Ayscue,
The Johns Hopkins University, Baltimore, Maryland, published by the Natural Hazards Research and Applications Information Center, Institute of Behavioral Science, University of Colorado, November 1996. Abstract: "Property damage and loss from hurricanes have increased with population growth in coastal areas, and climatic factors point to more frequent and intense hurricanes in the future. This paper describes potential hurricane hazards from wind and water. Damage to residential structures from three recent intense hurricanes - Hugo, Andrew, and Iniki - shows that wind is responsible for greater property loss than water. The current state-of-the-art building technology is sufficient to reduce damage from hurricanes when properly applied, and this paper discusses those building techniques that can mitigate hurricane damage and recommends measures for mitigating future hurricane damage to homes." - online at www.colorado.edu/hazards/publications/wp/wp94/wp94.html
Thanks to reader Tammy X for discussing concerns about and procedures for removing fiberboard insulation from a flooded home in Tennessed 27 May 2010.
3711 Mill Street,
Wabash, IN 46992, 260-563-2111
Kansas State University, department of plant pathology, extension plant pathology web page on wheat rust fungus: see http://www.oznet.ksu.edu/path-ext/factSheets/Wheat/Wheat%20Leaf%20Rust.asp
"A Brief Guide to Mold, Moisture, and Your Home",
U.S. Environmental Protection Agency US EPA - includes basic advice for building owners, occupants, and mold cleanup operations. See http://www.epa.gov/mold/moldguide.htm
US EPA - Mold Remediation in Schools and Commercial Building [ copy on file as /sickhouse/EPA_Mold_Remediation_in_Schools.pdf ] - US EPA
US EPA - Una Breva Guia a Moho - Hongo [on file as /sickhouse/EPA_Moho_Guia_sp.pdf - - en Espanol
Associations: Sick House, Sick Building, SBS - Air Quality, Government, Private Associations and Information Resources
Atlas of Clinical Fungi, 2nd Ed., GS deHoog, J Guarro, J Gene, & MJ Figueras, Centraalbureau voor Schimmelcultures, Universitat Rovira I Virgili, 2000, ISBN 90-70351-43-9 (you can buy this book at Amazon)
"A Brief Guide to Mold, Moisture, and Your Home", U.S. Environmental Protection Agency US EPA - includes basic advice for building owners, occupants, and mold cleanup operations. See http://www.epa.gov/mold/moldguide.htm
"Disease Prevention in Home Vegetable Gardens,"
Department of Plant Microbiology and Pathology,
Department of Horticulture, University of Missouri Extension - extension.missouri.edu/publications/DisplayPub.aspx?P=G6202
Fifth Kingdom, Bryce Kendrick, ISBN13: 9781585100224, is available from the InspectAPedia online bookstore - we recommend the CD-ROM version of this book. This 3rd/edition is a compact but comprehensive encyclopedia of all things mycological. Every aspect of the fungi, from aflatoxin to zppspores, with an accessible blend of verve and wit. The 24 chapters are filled with up-to-date information of classification, yeast, lichens, spore dispersal, allergies, ecology, genetics, plant pathology, predatory fungi, biological control, mutualistic symbioses with animals and plants, fungi as food, food spoilage and mycotoxins.
Ozone Warnings - Use of Ozone as a "mold" remedy is ineffective and may be dangerous.
Rot concerns in buildings-some building mold such as Meruliporia incrassata "Poria" risks serious rot and hidden structural damage
US EPA: Una Breva Guia a Moho - Hongo [on file as /sickhouse/EPA_Moho_Guia_sp.pdf - - en Espanol
OTHER IAQ ISSUES: How To Find and Address Other Indoor Air or Indoor Environment Contaminants Besides Mold
Mold or allergens may not be the only or even the main indoor environmental contaminant. Don't let media attention to mold
cause so much enviro-scare fear that other, possibly more urgent hazards go un-addressed.
Rodents, Mice, Squirrel Control - I find high levels of mouse and rodent dander, fecal dust, and urine-contaminated dust in some buildings,
and high levels of these materials in building insulation in those locations. If you have a mouse problem, particularly if mice and their waste (fecals or urine) are contaminating
the building HVAC or building insulation, may need both steps to clean up or remove infected materials and steps to stop an ongoing
rodent problem. If squirrels are a problem, the cleanup needs to include closing off entry openings into the building. Get some
help from a licensed pest control expert.
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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.
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.
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