Information on this page is drawn from "Wood Feathers: Roofing Materials Distribution" published by the Department of Labor & Industries 
Project Background
The project reviewed here is an example of a job site delivery of roofing materials to houses in a new residential subdivision (new construction), and to an individual residence (re-roofing) near Vancouver, WA.
Rooftop stocking using flatbed trucks with powered conveyors was observed. Tasks included driving to/between worksites, positioning the conveyor, loading roofing materials onto the bottom end of the conveyor, and unloading materials at the top of the conveyor.
Concerns
The primary tasks of concern were the loading/unloading of roofing shingle bundles. The weight of the bundles, and the frequency with which they are loaded and unloaded from the conveyor during that portion of the day when workers are actively stocking materials onto the roof, results in large amounts of lifting for both the "bottom man" and the "top man" using the conveyor. 4-5 bundles per minute (12-15 seconds between lifts), or more, are commonly loaded onto the conveyor.
Suggestions
A previous WISHA demonstration project report (Allied Building Products, December 2002, http://www.lni.wa.gov/wisha/ergo/demofnl/AlliedDemoFinal.pdf suggested that limiting the loading rate of shingle bundles onto the conveyor to 2-3 bundles per minute (a lift every 20 to 30 seconds) would significantly reduce the potential for overexertion lifting injuries. As described above, this rate is often exceeded during typical conveyor use.
Wood Feathers' practice of using powered conveyors for rooftop stocking of building materials is a standard industry practice that reduces manual handling of materials and reduces the time required for rooftop stocking. This project reviewed the lifting demands of this standard practice and identified possible means for further lifting reductions.
Note: An alternative technique - use of an articulating arm boom truck to lift and suspend pallet loads of shingle bundles over the roof top for unloading - was not observed as part of this demonstration project. The boom truck features greater reach of materials up and over roofs, but is generally only used for delivery to new construction, with unfinished driveways, because the truck's outriggers require additional width to set up and they may cause damage to finished driveways. The boom truck hauls less roofing material than standard conveyor trucks, and results in more rapid lifting for the "top man" when unloading material onto the roof. Thus the boom truck was not included in this project and would need to be evaluated separately.
Results of Project
The following tables summarize the results of this demonstration project that examined rooftop delivery using a standard powered conveyor:
Summary
Rooftop stocking of commonly available shingle bundles exposes workers who are loading and unloading powered rooftop conveyors to heavy, frequent, and awkward lifting and carrying of shingle bundles.
Current practices have been reviewed, and suggestions made, for possible modifications to the rooftop stocking task that could reduce the amount of lifting and carrying required by this task.
Roofing industry employers may want to try some of these ideas, or other methods they feel would be effective, to determine if any of them would be useful for reducing the lifting and carrying required for this task.
