Wood shingle roof, valley flashing NY (C) Daniel Friedman Wood Shingle or Shake Roof Flashing Details
     

  • FLASHING WOOD ROOF DETAILS - CONTENTS: Flashing details for wood shingle or shake roofs
    • Use of copper flashing on wood shingle/shake roofs
    • Valley flashing details for wood shingle/shake roofs
    • Chimney flashing recommendations for wood shingle/shake roofs
    • Step flashing bend dimensions for roofing
    • Best practices for roofing material installation, flashing, ventilation, nailing, underlayment
  • POST a QUESTION or READ FAQs about how to install, inspect, troubleshoot & repair roof flashing on wood shingle or wood shake roofs
  • REFERENCES

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Flashing details for wood shingle or shake roofs:

This article discusses flashing installation details for wood shingle or wood shake roofs. This article series discusses best practices in the selection and installation of residential roofing. This article includes excerpts or adaptations from Best Practices Guide to Residential Construction, by Steven Bliss, courtesy of Wiley & Sons. Our page top photo shows a wood shingle roof on the historic Mesier Homestead in Wappingers Falls, NY.

Also see the roofing article links listed at the "More Reading" links at the bottom of this article and our roofing home page: ROOFING INSPECTION & REPAIR.

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Flashing Specifications for Wood Shingle / Shake Roofs

Figure 2-46: Wood Roof Shingle installation detail (C) J Wiley, S BlissAdapted/paraphrased with permission from Best Practices Guide to Residential Construction, chapter on BEST ROOFING PRACTICES [Click any image or table to enlarge and add detail.]

Roof flashings should be at least 26-gauge, corrosion resistant sheet metal, preferably painted galvanized steel or painted aluminum.

Copper Flashing and Cedar Roofing?

Copper is a popular flashing material with wood roofs, although some experts caution against using copper in direct contact with red cedar or its runoff, since the soluble tannins in cedar can etch copper and, in extreme cases, lead to perforation of the flashing within 10 to 20 years (see also “FLASHING WALL DETAILS - Copper,” and “Metal Choices for Metal Roof Systems - Copper”).

Premature wood shingle roof failures have been documented in areas of the eastern United States that are subject to acid rain, leading the Cedar Shake and Shingle Bureau to advise against using copper flashing in areas east of the Great Lakes that are exposed to acid rain.

Another approach endorsed by the Copper Development Association is to design flashing joints with a cant or hem that holds the edge of the cedar shingle slightly away from the flashing. The gap prevents water from being wicked into the joint, bathing the copper in the acidic solution.

Valley Specifications for Wood Shingle/Shake Roofs

Wood roofs typically use open valley designs. While the International Residential Code (IRC) only requires the valley flashing to extend a minimum of 10 inches up each side of the valley for shingles and 11 inches for shakes, most contractors install 24- to 36-inch-wide valley flashing based on the area and pitch of the roof planes being drained.

Wood shingle roof, chimney flashing NY (C) Daniel FriedmanThe valley metal should be protected by an extra layer of 36-inch-wide No. 30 felt installed directly under the metal or a layer of self-adhesive bituminous membrane applied directly to the sheathing.

It is best to set aside the widest shingles or shakes for use in the valley to keep nails at least 12 inches from the valley centerline (Figure 2-52) shown above.

Chimneys and Skylight Flashing Specifications for Wood Shingle/Shake Roofs


Chimneys on wood shingle or shake roofs are flashed conventionally, using step flashing on the sides in accordance with Table 2-16 below.

Use a soldered apron flashing below the chimney and a soldered head flashing at the top. Larger chimneys with significant water flow behind them should have a chimney cricket above.

[Click table below to enlarge and add detail]

Figure 2-46: Wood Roof Shingle installation detail (C) J Wiley, S Bliss

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

Wood Shingle Roofing Materials & Equipment Suppliers

Where to Buy Ridge Vents

  • Air Vent/A Gibraltar Company www.airvent.com A complete line of roof ventilation products, including shingle-over and exposed-ridge vents with exterior wind baffles and internal weather filters. Also soffit and drip edge vents and passive and powered attic turbine-type vents.
  • Benjamin Obdyke www.benjaminobdyke.com Shingle-over ridge vents. Low-profile Roll Vent uses nylonmatrix. Extractor vent is molded polypropylene with internal and external baffles.
  • Cor-A-Vent www.cor-a-vent.com Shingle-over low-profile ridge vents, including Cor-a-vent, Fold-a-vent, and X-5 ridge vent, designed for extreme weather. Corrugated core.
  • GAF Materials Corp. www.gaf.com Cobra vent: roll-out shingle-over ridge vent with a polyester-matrix core 102 CHAPTER 2 | Roofing
  • Mid-America Building Products www.midamericabuilding.com Ridge Master and Hip Master shingle-over molded plastic ridge vents with internal baffles and foam filter
  • Owens Corning www.owenscorning.com VentSure corrugated polypropylene ridge vents; also passive roof vents and soffit vents
  • Trimline Building Products www.trimline-products.com Shingle-over low-profile ridge vents, Flow-Thru battens for tile roofs
  • Elk Premium Building Products www.elkcorp.com Highpoint polypropylene shingle-over ridge vents
  • Tamko Roofing Products www.tamko.com Shingle-over ridge matrix–type Roll Vent and Rapid Ridge (nail gun version) and Coolridge, which is molded polypropylene with external and internal baffles

Venting Wood Roof Underlayments

  • Benjamin Obdyke www.benjaminobdyke.com Cedar Breather, a 3/8 -in.-thick matrix-type underlayment designed to provide ventilation and drainage space under wood roofing

More Information about Roofing Materials, Methods, Standards

  • Asphalt Roofing Manufacturers Association (ARMA) www.asphaltroofing.org
  • Cedar Shake and Shingle Bureau www.cedarbureau.org
  • Metal Roofing Alliance www.metalroofing.com
  • Tile Roofing Institute www.tileroofing.org

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

 

Continue reading at WOOD ROOF INSTALLATION SPECS or select a topic from the More Reading links shown below.

Also see WOOD ROOF SHAKES INSTALLATION.

More Reading

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