Two Types of Joints for Two Classifications of Use
STUD USE ONLY. A Stud Use Only joint serves perfectly when the primary long term load is grain. Also labeled VERTICAL USE ONLY, these joints are usually 3/8" to 5/8" long. The fingers may have blunt tips. The adhesives used are water resistant, but must be used inside. Stud use only lumber is available up to 2" X 6" X 12'.
CERTIFIED EXTERIOR JOINTS. Lumber with Certified Exterior Joints is not restricted to any type of loading. These joints will usually have jointed fingers 7/8" to 1-1/8" long. The adhesives used in the joints are waterproof and will not creep. This joint can be used in any width or length of American Standard lumber.
Both joint types may qualify for dimension lumber grades as Stud, 3, 2, 1 or Select Structural. Identify them by the information on the grademark. Without an approved grademark, it is impossible to tell structurally finger jointed lumber from nonstructural jointed products. Each piece of approved lumber must have a grademark identifying its use approval, mill I.D., grade and the quality control agency.
Grades for structural Finger Jointed lumber use the same rules as unjointed lumber. The wood in the joints actually meets stricter requirements. Design values are also the same as those for unjointed lumber. This allows Structural Finger Jointed Lumber to be used
interchangeably with unjointed lumber.
Lumber for construction use in the US is graded under the Department of Commerce Voluntary Product Standard PS 20-94. The American Lumber Standard Committee (ALSC) Initiated this standard and is the Accrediting body for agencies that supervise grademarking of Glued Structural Lumber. Timber Products Inspection Inc. (TP) has approval from the ALSC to supervise all approved finger jointing Quality Control Programs including their own
Stud Use End Jointed Lumber Program.
