Wood Plank Roof Decks: Wood planks for roof deck construction shall be of sound, kiln dried, and solid sawn lumber. End joints of each piece of decking shall be staggered. End joints shall be centered over the roof deck framing supports so as to provide adequate bearing support and facilitate fastening to the framing supports without splitting. All boards shall be attached to intermediate roof deck framing supports according to the fastening schedule specified for the required wind uplift and loads expected for each particular roof deck.

Moisture: The effects of moisture can damage Wood. Wood panels and wood planks shall be protected from the weather both during storage on the job site and after installation. The roof system shall be installed as soon as practical after installation of the wood deck so as to limit moisture exposure.

Cants: If the roof assembly design places cants in direct contact with the wood deck, designers shall specify solid wood cants in lieu of pressed fiber or other materials more prone to moisture absorption.

High Humidity Buildings: If the building's interior is expected to have high relative humidity, the deck manufacturer's recommendations shall be consulted for specific moisture protection, possible vapor retarder or ventilation requirements, and other precautions.

Protection: Designers shall incorporate into the project specifications the APA storage and handling guidelines printed in the APA Product Guide for Grades and Specifications. The APA instructions outline protection for stored wood deck products.

Preservative Treated & Fire Retardant Wood: Caution shall be exercised when decks are constructed of wood that has been treated with an oil based preservative. Many roof systems are not compatible with oil based preservatives, and as a result Fields requires that wood decks be constructed with wood that has been treated with a non-oil preservative pressure treatment, or with non-treated, kiln dried lumber. Fields shall be consulted as to the specific recommendations for a BUR membrane installation over preservative treated wood decking. For additional information regarding preservative wood treatment, consult the American Wood Preservers Association.

Because of the deterioration of some fire retardant treated wood panels caused by chemical reaction, special consideration shall be given to evaluate the sounds of existing fire retardant wood panel decks prior to design and installation of a reroofing system.

Weather & Temperature: Installation of the wood roof deck shall be scheduled and coordinated with weather and temperature conditions that allow for correct installation of the roof assembly. If panel or wood plank roof deck components are damaged from weather exposure, they shall be repaired or replaced prior to installation of the roof system.

Building Heat: When wood plank roof decks are installed on newly constructed buildings, the building shall be heated gradually after the roof system is installed. This will prevent rapid changes in wood moisture content that could result in either the twisting of the deck or warping of the dimensional lumber. Such warping can alter drainage patterns and damage the roof assembly.

Deck Panel Spacing, Attachment, & Wind Uplift Information: The information contained herein is limited and some information has been excerpted from the American Plywood Association documents. Deck designers and installers shall review the most current information from the American Plywood Association. As recommended by APA, correct spacing shall be provided when installing wood panel decking so as to allow for expansion. Unless the panel manufacturer recommends otherwise, spacing between panel end and side joints shall be .125". Panel spacer type edge clips such as H-clips are required for the installation of wood panel roof decks.

APA has published the Roof Sheathing Fastening Schedules for Wind Uplift. This report identifies three fastening schedules for various wind uplift conditions; basic uplift, intermediate uplift, and high wind uplift. The fastening schedules offer attachment information for three fastening zones, or areas of the roof. The fastening zones are described as follows: The following APA fastening diagrams are for reference only. Designers shall contact APA for specific wood panel roof deck fastening requirements and revisions or updates to these requirements.

Illustration 10: APA recomended roof fastening zones for wind uplift

Zone 1 is the field of the roof; Zone 2 is the first 4 feet from the eave and ridge lines; and Zone 3 is the first 4 foot by 5 foot section from each corner and the first 5 feet including a 1 foot overhang at rake edges.

The following APA fastening schedule in Chart 3 assumes framing spaced at 24" on center or less, and that the panels are .625" thick or more, and that the mean roof height is 35' or less. If the building is in a special wind region, as identified in the American Society of Civil Engineers document ASCE 7-93, an engineered design is required.

Chart 3: Nail fastening schedule for wind uplift loads

Insulation Board Attachment: Insulation boards shall be mechanically fastened to wood panel or wood plank decks.

BUR Membrane Attachment: The BUR membrane shall not be adhered directly to wood roof decks. A Fields base sheet or layer of rigid insulation shall be mechanically attached to the wood roof deck to serve as a separation for the Fields BUR membrane. UK5 KraftFelt is required to be nailed first over wood decks so as to prevent asphalt from dripping into the building. In severe climates, where roof system configuration permits, a minimum layer of insulation shall be fastened over wood decks. On wood decks not covered with insulation, the UK5 KraftFelt and Fields base sheet shall be mechanically fastened over the wood deck with annular threaded or ring shank nails. Fasteners shall penetrate and puncture the underside of wood panel roof decking.

Page: 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13

About Fields | Services | Product Guide | Advertising | BUR Systems

Copyright © 2003 Fields Company, LLC. All rights reserved.