Dear James: There quite a few projects I need to do around my house. How do I decide when and where to use particleboard, plywood or oriented strand board? - Rich J.

Dear Rich: You must have visited your home center store recently and done your research. Those are the basic four materials to use for flat structural members and each is best for specific applications.

If you are ever unsure about a specific project, plywood is always an acceptable choice, but not always the best or the least expensive. Actually, there are many different grades of plywood available and the properties and prices vary greatly among them. When you buy plywood, first discuss your project with the lumber salesperson so you get the proper grade.

Medium density fiberboard (MDF) is made of fine wood fibers from waste wood and resins to hold them together. Since it is made from waste wood, it is an earth-friendly material to use. It is a high-quality strong product and is typically used for furniture, shelving, molding and cabinets. It is often finished with a laminate or veneer surface or just painted.

MDF is easy to work with using standard woodworking tools and is particular good for holding screw threads and resisting tear-out. It is usually available in 1/2- to 3/4-inch thick sheet which are slightly larger than standard 4- by 8-foot sheets. It is also available in precut shelving sizes for easy installation.

Particleboard is slightly different in that it uses waste sawdust mixed with the resins. It also is strong and heavy and will not warp or bow as plywood sometimes does. It is primarily used for furniture, underlayment and a base for countertops. It does not hold up well in wet locations where it may swell from excessive moisture. Consider the likelihood of heavy moisture in a location before using it.

Like MDF, particleboard is easy to work with. Since both these materials use resins, it is wise to wear a breathing mask when sawing them. Particleboard does not have as high a tear-out strength as MDF. It is finished with laminate or veneer, but seldom just painted. You can find it in standard 4 by 8-foot sheets and the home center store will usually cut it down for you for free.

Oriented strand board (OSB) is a completely different material than the previous two mentioned. It is primarily used as sheathing and underlayment for house construction and remodeling projects. It is ideal for exterior wall sheathing, roofing base and floors inside your house.

OSB is produced somewhat similar to plywood in that it is made from several layers of thin sheets. Instead of using thin sheets of solid wood as plywood does, OSB is made from small 1 by 4-inch flakes of wood which are bonded together by resins.

The strands in the chips in each thin sheet all go in one direction. Each successive thin sheet is rotated 90 degrees from the one below it. This creates a multilayer working sheet which is extremely stable and will not warp or bow.

The surface of OSB is not typically finished because it always covered with some other material (siding, flooring, shingles, etc.). It can be easily cut with a power saw, but it is not generally shaped or sanded as MDF and particleboard are.

Send your questions to Here's How, 6906 Royalgreen Dr., Cincinnati, OH 45244 or visit www.dulley.com.