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This article discusses choices of wood siding materials for buildings: shingles, clapboards, and wood product grades and appearance profiles. This article series discusses best practices construction details for building exteriors, including water and air barriers, building flashing products & installation, wood siding material choices & installation, vinyl siding, stucco exteriors, building trim, exterior caulks and sealants, exterior building adhesives, and choices and application of exterior finishes on buildings: paints, stains. This article series includes excerpts or adaptations from Best Practices Guide to Residential Construction, by Steven Bliss, courtesy of Wiley & Sons.

Also see WOOD SIDING INSTALLATION and SIDING WOOD, FAILURES OVER FOAM BOARD.

© Copyright 2012 InspectAPedia.com, Daniel Friedman, Steve Bliss, Wiley & Sons, All Rights Reserved. Information Accuracy & Bias Pledge is at below-left. Use page top links to major topics or use links at the left of each page to navigate within topics and documents at this website. Green links show where you are in a document series or at this website.

Guide to Wood Siding Products on buildings: Choices, Installation, Maintenance

Adapted/paraphrased with permission from Best Practices Guide to Residential Construction. Steven Bliss.

Solid wood siding materials (clapboards, drop-leaf or novelty siding, wood shingles, vertical wood siding, board and batten, etc.) s have been used for hundreds of years and remain popular in many sections of the United States and other countries despite their need for regular refinishing. Our photo of a wood clapboard-sided home (left) shows the Daniel Vose house, referred to historically as the Suffolk Resolves historic home (1774) relocated to Milton MA. (See ARCHITECTURE & BUILDING COMPONENT ID.) In the Northeastern U.S., the most popular wood siding profile remains a simple bevel siding, or “clapboard.” In the western states, heavier profiles such as channel rustic are more common. Plywood building siding products such as "T-111" grooved siding products installed in 4' x 8' sheets has been widely used throughout the U.S. since the 1970's.

Examples of Wood Siding Products & Materials

Above left, traditional board and batten siding (Pleasant Valley, NY) traditionally used on barns. Battens are nailed over gaps between vertical board siding, taking care to nail only on one side to avoid splitting. Above right: wood clapboards installed rough-side out for a more rustic look and one that according to some, may provide better paint adhesion. See PAINT FALURE, DIAGNOSIS, CURE, PREVENTION

Above left, Masonite-type wood product siding: hardboard. Above-right Hardiplank wood siding with some peeling stain concerns. Details are at JamesHardie HardiPlank Siding. Also see

SIDING HARDBOARD
  Abatibi Siding Claims
  Boise Cascade Siding Claims
  JamesHardie HardiPlank Siding
  Masonite Siding Claims

Above left, wood shingle siding, Two Harbors MN. At above right this 1960's ranch home in New York was sided with brushed cedar shingle siding.

Species of Wood Choices for Wood Siding

Red cedar remains the wood siding material of choice due to the natural decay resistance of the heartwood and its attractive appearance when stained or finished clear.

Other decay-resistant woods are popular in the regions where they are produced: for example, redwood on the West Coast and cypress in the Southeast and Gulf Coast.

On projects where premium wood species are not affordable, builders also use a wide variety of softwoods, including pine and spruce, which are not naturally resistant to decay.

While most suppliers of wood siding now recommend back-priming and priming of cut ends, these details are even more critical with the less decay-resistant species.

Our photograph of brushed wood cedar shingle siding (above) on a Canadian home was provided by Carson Dunlop Associates.

Grading Methods for Wood Siding Products

Since wood siding is a nonstructural application, grading is generally for appearance only and is not governed by building codes. Most western species used for siding are graded according to one of the established grading agencies such as the Western Wood Products Association (WWPA). Still, manufacturers are free to name the grades as they choose for marketing purposes. So one company’s “Select” grade may be quite different from another’s. For this reason, it is best to examine the material before specifying or purchasing.

Premium Grades of Wood Siding

Western woods are generally labeled either premium or knotty grades. Premium grades have more heartwood and fewer defects and are typically kiln dried. The highest grades of cedar are typically Clear VG (vertical grain) Heart and Clear Heart. Premium grades for other western woods include C Select, D Select, Superior, and Prime.

Knotty Grades of Wood Siding

In general, “sound tight knots” or “select tight knots” (STK) indicates that there are no knots that will come loose or affect the performance of the siding. Other common designations are Select Knotty, Quality Knotty, 2 & Better Common, 3 & Better Common, and NPS (no prior selection). Since there are no uniform standards for these designations, an inspection of the material is important.

Moisture Content Targets for Wood Siding on buildings

Ideally, the siding should be installed at close to its equilibrium moisture content for the local climate (see Table 1-2 below). In general, unseasoned or green wood is shipped with a moisture content of greater than 19%. Air-dried or kiln-dried siding is shipped with a moisture content of 15 to 19%. In western woods, dry has a different meaning for premium and knotty grades.

In premium wood siding grades, dry means that the siding has no more than 15% moisture content. In knotty grades, dry means that the moisture content does not exceed 19%. Dry siding stored on the site (stickered if possible) will usually acclimate to local conditions in a week to 10 days. Unseasoned wood may need 30 days or longer to acclimate.

Wood Siding Profiles

Because horizontal profiles naturally shed water, they resist water leakage better than vertical profiles. Also vertical wood siding is prone to wick up moisture from the bottoms of the boards, particularly where there is snow buildup or splashback. Diagonal siding is the most prone to leakage since water is conducted down the joints to window headers and other possible entry points. The most common profiles with typical installation details are shown in Figure 1-7 above.

-- Adapted with permission from Best Practices Guide to Residential Construction

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Technical Reviewers & References

• InspectAPedia.com^® - Daniel Friedman - Publisher & Editor.
• 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.
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BEST PRACTICES GUIDE to Residential Construction
EXTERIOR WALL SIDING TRIM & FINISHES
  ADHESIVES, EXTERIOR CONSTRUCTION
  CAULK GUN TYPES, CHOICES
  CAULKS & SEALANTS, EXTERIOR
  FIBER CEMENT SIDING
  FLASHING MEMBRANES PEEL & STICK
  FLASHING for METAL ROOFS
  FLASHING ROOF-WALL SNAFU
  FLASHING WALL DETAILS
  GALVANIC SCALE & METAL CORROSION
  GLUES ADHESIVES, EXTERIOR CONSTRUCTION
  HOUSEWRAP AIR & VAPOR BARRIERS
  HOUSE PARTS, DEFINITIONS
  HOUSEWRAP INSTALLATION DETAILS
  HOUSEWRAP PRODUCT CHOICES
  HOUSEWRAP at SILLS, SOLES, TOP PLATES
  LOG HOME GUIDE
  PAINT / STAIN SELECTION & PROCEDURES
  RAIN SPLASH-UP SIDING DAMAGE
  SIDING, Sheathing Identification - Photo Guide
  SIDING, ALUMINUM
  SIDING, ASBESTOS CEMENT SHINGLES
  SIDING ASPHALT ROOF SHINGLES on WALLS
  SIDING ASPHALT SHINGLE or SHEET
  SIDING DAMAGE by SPLASHBACK
  SIDING EIFS & STUCCO
  SIDING, FIBER CEMENT
  SIDING HARDBOARD
  SIDING, LOG
  SIDING STEEL
  SIDING VINYL
  SIDING, WOOD PRODUCT CHOICES
  SIDING, WOOD INSTALLATION
  SIDING WOOD, FAILURES OVER FOAM BOARD
  SIDING WOOD, FLASHING DETAILS
  SIDING WOOD SHINGLE INSTALLATION
  STONE CLEANING METHODS
  STUCCO WAll FAILURES DUE TO WEATHER
  STUCCO WALL METHODS & INSTALLATION
  TRIM, EXTERIOR CHOICES, INSTALLATION
  VINYL SIDING INSTALLATION
  WOOD SHINGLE INSTALLATION
  WOOD SIDING PRODUCT CHOICES
  WOOD SIDING INSTALLATION
  WOOD SIDING FLASHING DETAILS
  WATER BARRIERS, EXTERIOR

• Best Practices Guide to Residential Construction, by Steven Bliss. John Wiley & Sons, 2006. ISBN-10: 0471648361, ISBN-13: 978-0471648369, Hardcover: 320 pages, available from Amazon.com and also Wiley.com. See our book review of this publication.
• Carson, Dunlop & Associates Ltd., 120 Carlton Street Suite 407, Toronto ON M5A 4K2. (416) 964-9415 1-800-268-7070 info@carsondunlop.com. Thanks to Alan Carson and Bob Dunlop, for permission to use illustrations from their publication, The Illustrated Home which illustrates construction details and building components. Carson Dunlop provides home inspection education including the ASHI-adopted Home Inspection Training Program (home study course), publications such as the Home Reference Book, report writing materials including the Horizon report writer, and home inspection services. Alan Carson is a past president of ASHI, the American Society of Home Inspectors.
• Paul Galow - technical consultant on networking, LAN design, applications support. Galow Consulting Services, 914-204-1749, email: paulgalow@galowconsulting.com
• John Rudy, Advantage Home Inspections, Flemington N.J. 08822 home inspector, 908-806- 6364, Home, Radon & Termite Inspections, Central & Parts of North New Jersey, email: jonadvantage1@yahoo.com
• Masonite Woodruf® Roofing or Masonite OmniWood® Siding Lawsuit Settlement Notice - PDF file

Books & Articles on Building & Environmental Inspection, Testing, Diagnosis, & Repair

• Our recommended books about building & mechanical systems design, inspection, problem diagnosis, and repair, and about indoor environment and IAQ testing, diagnosis, and cleanup are at the InspectAPedia Bookstore. Also see our Book Reviews - InspectAPedia.
• Best Practices Guide to Residential Construction, by Steven Bliss. John Wiley & Sons, 2006. ISBN-10: 0471648361, ISBN-13: 978-0471648369, Hardcover: 320 pages, available from Amazon.com and also Wiley.com. See our book review of this publication.
• Decks and Porches, the JLC Guide to, Best Practices for Outdoor Spaces, Steve Bliss (Editor), The Journal of Light Construction, Williston VT, 2010 ISBN 10: 1-928580-42-4, ISBN 13: 978-1-928580-42-3, available from Amazon.com
• The Journal of Light Construction has generously given reprint permission to InspectAPedia.com for this article. All rights and contents are ©Journal of Light Construction and may not be reproduced in any form.
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