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Show Glued-Wood Barn Rafters Are Durable The appearance on the market of glued laminated wood barn rafters, and members in which studs and rafters are combined in one continuous piece, is of interest to farmers contemplating the building of new barns. This mod- boards or strips. Joints properly made with this glue will last as long as the rafters, if the wood remains dry in service. If the wood becomes wet or damp, however, how-ever, and remains so for long periods, per-iods, the joints will eventually weaken. wea-ken. It should be pointed out that moisture cfllnditions unfavorable unfa-vorable to the glue joints would also be harmful to wood either in solid members or laminations. Another question often asked is whether condensed moisture em way of building barns has given rise to a number of questions ques-tions dealing mainly with the durability dur-ability of this type of construction. construc-tion. These rafters are made by gluing together boards, usually of inch lumber, one on top of the other with the direction of the grain of each board parallel to the length of the rafter. In gluing, the rafters-and-stud- members are bent to the reOjUired curvature and this curvature is retained when the glue sets. One of the questions frequently j asked the IT. S. Forest Products . Laboratory. Madison. Wis., where j the engineering of laminated wooden structural members both straight and bent, was introduced ! in this country, is whether the glue joints are durable. Laminated barn rafters at present are glued with casein glue, the most moisture? mois-ture? resistant glue that is thus far considered practicable for gluing U thick assemblies of in the barn will cause the rafter laminations to separate. No barn owner can afford to tolerate conditions con-ditions that cause moisture condensation conden-sation in barn walls regardless of whether laminated or solid members are used as framing, especially es-pecially in cases where studs, rafters, and other framing lumber are enclosed by sheathing and lining and possibly inculating materials. ma-terials. In other words, conditions which will cause the separation 1 of laminations in rafters well 1 glued with casein glue w-il also in time cause rotting of solid studs and rafters, perhaps even to the point where a severe wind storm would lift the barn off the f-un- ; elation due to rotting through of : the studs near the plate. 1 Woods recommended for lamb- 1 ated rafters would be the same as j fr solid rafters. S-ime bam rafter species glue more easily than c others, but all can be satisfac- torily glued. r |