OSB - Oriented strandboard

Oriented strandboard (OSB) has been gaining popularity since 1980's in the North America in the construction industry, especially the new residential house sector.

OSB panels are manufactured using residue of wood mill or small-diameter logs that are previously under-utilized. They have a viable potential in time of curtailed timber supplies due to reducing forest, demand from conservation groups and public for saving the environment, and more stringent logging regulations.

OSB panels form a second vapor barrier in the building envelope. The wood stud and insulation, between the vapor barrier on the warm side and OSB on the cold side, have a very low drying potential. This may cause problems related to excessive moisture accumulation. [J. Rao, 1999]

Oriented Strandboard (OSB) is a structural panel that competes directly with softwood plywood in many construction applications. particularly exterior wall and roof sheathing and nearly half of all floor decking. OSB was first produced in Canada in 1964. Since then, capacity has increased steadily, but it wasnˇŻt until the mid 1980s that capacity expanded rapidly. North American production capacity in 1996 was estimated at 15,276 ˇÁ 103 m3, nearly twice the 1990 capacity (2). The number of operating mills producing OSB increased by more than 50 percent between 1990 and 1996. This increase in the rate of industry expansion is a direct result of harvest restrictions on West Coast timber. OSB is made from small diameter softwoods and previously underutilized hardwoods and is therefore not dependent on the large diameter logs needed by the softwood plywood industry. West Coast inland mills producing OSB primarily use lodge pole pine logs averaging about 0.25 to 0.3 m (10 to 12 in.) in diameter. compared with the 0.4- to 0.5-m (16 to 20-in.) logs needed for softwood plywood (Table 1). Mills in the South producing OSB use pine plantation thinning and Southern Pine and soft hardwood logs that average about 0.2 m (8 in.) in diameter. Log diameter in the South has gotten smaller. Northern mills rely almost exclusively on aspen logs 0.15 to 0.3 m (6 to 12 in.) in diameter. The diameter of these logs has remained fairly constant. [Spelter, H., McKeever, D., and Durbak, I., 1999]

OSB is not allowed in Europe due to its large chemical emission from the glue in the board.

IRC/NRC measured properties of OSB.

In Europe, there are research projects on both properties measurement and experiments of OSB in use, (in Europe, OSB is chip board)

Increasing permeance of exterior sheathing by OSB and the impact on dry potential.

Reducing the impact of chemical emission from the OSB in building envelope to the indoor environment.

Guidelines for using OSB as exterior sheathing (how it differs from constructions using other panel materials)

Vancouver: The material used for exterior sheathing did not appear to be a major factor. OSB sheathings, which were more commonly used in the total sample, were used on a disproportionately higher number of problem walls with but plywood sheathing was also used in walls that exhibited major problems.

(K. Alan Carlton ) For example, but not limited to, failing to provide an 1/8" gap at ends and edges (between sheets) of Plywood & OSB sheathing, used as flooring, roof & wall sheathing and exterior wall wind bracing.

Fisette, 1997, Choosing between oriented strandboard and plywood :: "Osb and plywood share the same exposure durability classifications: Interior, Exposure 1 (95% of all structural panels), Exposure 2 and Exterior. They share the same set of performance standards and span ratings. Both materials are installed on roofs, walls and floors using one set of recommendations. "

"Logs are ground into thin wood strands to produce oriented strandboard. Dried strands are mixed with wax and adhesive, formed into thick mats, and then hot-pressed into panels. DonˇŻt mistake osb for chipboard or waferboard. Osb is different. The strands in osb are aligned. ˇ°Strand pliesˇ± are positioned as alternating layers that run perpendicular to each other. This structure mimics plywood. Waferboard, a weaker and less-stiff cousin of osb, is a homogeneous, random composition. Osb is engineered to have strength and stiffness equivalent to plywood. -- Fisette, 1997, Choosing between oriented strandboard and plywood ::

Forest Products Society - conference and meeting abstracts

Abstracts of many wood related conferences is available in .pdf, in the Conference section.

as sheathing

A precision weighing system for helping assess the hygrotherma response of full-scale wall assemblies, by Maref, W.M. Lacasse, M.A. and Krouglicof, N., 2001

--------

Choosing between oriented strandboard and plywood, by Fisette, P., 1997

OSB lap siding debacle

Durability of energy-efficient wood-frame houses, by Smulski, S., 1999

--------

EIFS hygrothermal performance due to initial construction moisture as a function of air leakage, interior cavity insulation, and climate conditions, by Salonvaara, M. H. and A. N. Karagiozis, 1998

OSB is one engineered wood product

Engineered wood products: a response to the changing timber resource, by McKeever, D. B., 1997

--------

Envelope Drying Rates Experiment, Final Report, by Hazleden, D., 2001

WVT, experiment

Evaluation of moisture diffusion theories in porous materials, by Alvarez, J. C., 1998

--------

Evaluation of vapour diffusion ports on drying of wood-frame walls under controlled conditions, by Hazlen, D. G. and Morris, P. I., 2002

test compare water resistance of OSB & hard wood siding

Field observations and laboratory tests of water migration in walls with shiplap hardboard siding, by Tsongas, G. A., Govan, D. P. and J. A. McGillis, 1998

--------

Fungal susceptibility of interior commercial building panels, by Laks, P.E., Richter, D.L., Larkin, G.M, 2002

--------

High-performance wood-based panels substitute breathable membranes on external wall sheathings, by Marquardt, H. and Mainka, G. W., 2001

--------

How durable is structural sheathing?, by Quarles, S. L., 2001

as exterior sheathing reduce drying efficiency

Improving the drying efficiency of timber frame walls in cold climates, by using exterior insulation, by Ojanen, T., 1998

--------

Mold and decay resistance of common sheathing materials, by Laks, P. E., G. M. Larkin, and E. Keranen, 1999

--------

O86.1-94 Engineering Design in Wood (Limit States Design), by CSA, 1994

OSB as woos panel

Review of wood-based panel sector in United States and Canada, by Spelter, H., McKeever, D., and Durbak, I., 1999

structure performance of OSB as compared to other boards

Static Racking Behavior of Plywood, OSB, Gypsum, and FiberBoard Walls with Metal Framing, by Serrette, R.L., J. Encalada, M. Juadines, and H. Nguyen, 1997

--------

Survey of building envelope failures in the coastal climate of British Columbia, by Morrison Hershfield Limited, 1998

OSB as sheathing

Temperature and moisture performance of wall assemblies with fiberglass and cellulose insulation, by Rose, W. B. and McCaa, D. J., 1998

--------

U.S. timber production, trade consumption, and price statistics 1965 to 1999, by Howard, J. L., 2001

--------

Volatile organic chemicals emissions from OSB as a function of processing parameters, by Barry, A. O. and Corneau, D., 1999

--------

Wall sheathing creates headaches for builder, homeowners, by Carroll, M., 2001

Wood markets

Wood markets 2000 edition: the solid wood products outlook 2002 to 2006, by International Wood Markets Research Inc, 2000

--------

Wood used in new residential construction 1998 and 1995, by NAHB Research Center, 1999