WOOD ROOF MAINTENANCE - CONTENTS: Cleaning & maintenance advice for wood shingles & shakes on roofs. How to wash or clean wood roofs. Guide to using preservatives on wood shingles or wood shakes. Treatments to use & others to avoid using on wood roofs
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This article discusses the properties of wood roof shingles and shakes, including shingle grades, wood species used in roofing, and wood roof shingle or shake warranties.
This article series discusses best practices in the selection and installation of residential roofing. Our page top photo shows a wood shingle roof on the historic Mesier Homestead in Wappingers Falls, NY.
A number of factors affect the longevity of a wood roof.
Key factors include the durability of the wood, local humidity
and precipitation levels, and whether the roofing
was installed with adequate ventilation.
Other factors include
the slope of the roof (steeper slopes shed water
faster) and the presence of overhanging trees that shade
the roof and drop organic debris onto the roof, trapping
moisture on the surface. Some of these factors can be
controlled by the contractor; some managed by the homeowner.
Others, like the weather or the reduced durability
of second-growth cedar, are beyond our control.
Some simple steps that a homeowner can take to prolong
the life of a wood roof include:
Trim overhanging branches that drop pine needles or
leaves on the roof.
Clean debris out of gutters and off the roof, both the
surface areas and the keyways between shakes or
shingles. A garden hose can do an adequate job.
Ensure adequate year-round ventilation of the attic or
Install strips of zinc or copper at the ridge (can serve also
as a ridge cap) and midway across the roof on long
slopes. Runoff from these strips forms a mild solution
that reduces the growth of moss, mold, and mildew. This
is effective for up to 15 feet downslope from the metal.
If moss or lichen begin to grow, scrape it away and
scrub the area with a solution of 1 quart household
bleach, 1 ounce detergent, and 3 quarts warm water. See details at WOOD ROOF MOSS & LICHENS.
Over time, the natural extractives in cedar and other
decay-resistant species will leach out, making the wood
vulnerable to decay. Also, as the shingles dry out, they are
prone to cupping, checking, and splitting. At some point,
it may make sense to wash and treat the entire roof.
Washing or Cleaning Advice for Wood Roofs
Cleaning wood roofs with high-pressure
equipment is controversial and, in untrained hands, can
cause significant damage. It is best to use normal garden
hose pressure along with a brush or pump sprayer. To remove
dirt, mildew, and weathered gray residue, a consortium
of wood technology and coatings experts, including
the U.S. Forest Products Laboratory (FPL), recommend a
solution of sodium percarbonate (disodium peroxydicabonate)
With redwood and cedar, a second
wash with a solution of oxalic acid may be needed to remove
brown and black discoloration caused by tannins that
leached out of the wood. Concentrated oxalic acid is toxic
and should be handled with care.
Preservative Treatments for Wood Shingle / Shake Roofs
There are a number of commercial
treatments available to restore decay-resistance to
an aging wood roof. One effective and relatively benign
(to plants) treatment consists of a copper-naphthenate
compound called Cunapsol 5, which is diluted 1:4
with water and can be applied with a garden sprayer. The
treatment needs to be repeated approximately every
Although Cunapsol 5 and
similar waterborne treatments offer good protection
against mold, mildew, and decay fungi, they will not do
anything to slow down the cupping and splitting caused
by weathering. For that, an oil-borne treatment is required.
Effective wood roof shake or shingle preservative treatments include copper naphthenate
with a 3 to 4% metal content and copper octoate with a 1
to 2% metal content. These can be brushed on or dipped
(before installation) or professionally applied with spray
Semitransparent Oil-Based Preservative Stains on Wood Roofs
Semitransparent oil-based preservative stains work
well on rough-textured wood, such as shakes and shingles.
They provide some pigmentation and protect the
roof from decay for several years. Look for a product
with both a wood preservative and a water repellent.
Stains with a high percentage of pigment provide the best
protection against UV degradation. While preservative
stains are best applied before installing the shingles, a
surface application can significantly extend the life of
a wood roof.
Treatments to Use and to Avoid on Wood Shingles and Shake Roofs
According to the
Shingle and Shake Bureau, one should use only products
that are marketed and labeled as a cedar roof treatment,
that have an MSDS available, and that contain one or more
of the following: a water repellent, UV inhibitor, or U.S.
EPA-registered wood preservative.
The following treatments should never be used on wood shingles or shakes:
Film-forming finishes, including paints, solid stains,
waterproofers, sealants, and plasticizers
Any product with more than 40% solvents
Any products that contains unfortified linseed oil or
Any topical treatment marketed with fire-retardant
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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. 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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Green Roof Plants: A Resource and Planting Guide, Edmund C. Snodgrass, Lucie L. Snodgrass, Timber Press, Incorporated, 2006, ISBN-10: 0881927872, ISBN-13: 978-0881927870. The text covers moisture needs, heat tolerance, hardiness, bloom color, foliage characteristics, and height of 350 species and cultivars.
Green Roof Construction and Maintenance, Kelley Luckett, McGraw-Hill Professional, 2009, ISBN-10: 007160880X, ISBN-13: 978-0071608800, quoting: Key questions to ask at each stage of the green building process Tested tips and techniques for successful structural design
Construction methods for new and existing buildings
Information on insulation, drainage, detailing, irrigation, and plant selection
Details on optimal soil formulation
Illustrations featuring various stages of construction
Best practices for green roof maintenance
A survey of environmental benefits, including evapo-transpiration, storm-water management, habitat restoration, and improvement of air quality
Tips on the LEED design and certification process
Considerations for assessing return on investment
Color photographs of successfully installed green roofs
Useful checklists, tables, and charts
Roofing The Right Way, Steven Bolt, McGraw-Hill Professional; 3rd Ed (1996), ISBN-10: 0070066507, ISBN-13: 978-0070066502
Slate Roofs, National Slate Association, 1926, reprinted 1977
by Vermont Structural Slate Co., Inc., Fair Haven, VT 05743, 802-265-4933/34. (We recommend this book if you can find it. It
has gone in and out of print on occasion.)
Roof Tiling & Slating, a Practical Guide, Kevin Taylor, Crowood Press (2008), ISBN 978-1847970237, If you have never fixed a roof tile or slate before but have wondered how to go about repairing or replacing them, then this is the book for you. Many of the technical books about roof tiling and slating are rather vague and conveniently ignore some of the trickier problems and how they can be resolved. In Roof Tiling and Slating, the author rejects this cautious approach. Kevin Taylor uses both his extensive knowledge of the trade and his ability to explain the subject in easily understandable terms, to demonstrate how to carry out the work safely to a high standard, using tried and tested methods.
This clay roof tile guide considers the various types of tiles, slates, and roofing materials on the market as well as their uses, how to estimate the required quantities, and where to buy them. It also discusses how to check and assess a roof and how to identify and rectify problems; describes how to efficiently "set out" roofs from small, simple jobs to larger and more complicated projects, thus making the work quicker, simpler, and neater; examines the correct and the incorrect ways of installing background materials such as underlay, battens, and valley liners; explains how to install interlocking tiles, plain tiles, and artificial and natural slates; covers both modern and traditional methods and skills, including cutting materials by hand without the assistance of power tools; and provides invaluable guidance on repairs and maintenance issues, and highlights common mistakes and how they can be avoided.
The author, Kevin Taylor, works for the National Federation of Roofing Contractors as a technical manager presenting technical advice and providing education and training for young roofers.
The Slate Roof Bible, Joseph Jenkins, www.jenkinsslate.com,
143 Forest Lane, PO Box 607, Grove City, PA 16127 - 866-641-7141 (We recommend this book).