Criticism of Plank Frame
Barn Construction.
From J. M. B., Monroeton, Pa.—In the December issue of Carpentry and Building, page 327, the correspondent “S. H.” of Minneapolis wants to know the weak points of his barn frame, a sketch of which was presented in connection with his communication. I think one weak point is what he calls the plate in the gable, which is made of two 2 × 8 inch pieces, equal to a 4 × 8 inch, with a span of at least 30 feet between purlin posts, which are only 2 × 6 inches. In my opinion, with the hay mow filled with hay, the gable will bulge or spring out, as the weight, 45 to 50 tons, will exert quite a pressure. As to the remedy I am not so clear. He might use a flat truss or a beam large enough to stand the pressure; one, say, 16 inches wide at the center and tapering to 8 inches at each end. I will say, in conclusion, that I have had no experience with plank frames.
Is the Barn Frame of
Sufficient Strength?
From C. G., Vergennes, Vt.—I send herewith a rough sketch of bent of barn which I intend to put up in the spring. It is 30 feet wide and has 26-foot posts. What I wish to know is this: Is the truss strong enough to carry the load that will be put upon it? I would like to have the “wood butchers” take hold of it and tear it apart and tell me what to put in its place.
From John L. Shawver, Bellefontaine, Ohio.—Permit me to offer a substitute for the barn frame proposed by the correspondent “C. G.” of Vergennes, Vt., in the March issue of the paper. His timber trusses take up too much room, and at the same time the timbers are too expensive for this day and age. We place a little more timber in the joist bearer and prefer it in a different shape. He suggests 7 × 8 inches, and this would be 30 feet in length. We would use three 2 × 10’s, and could use any lengths to make the 30 feet; consequently our timbers could be purchased at much less cost. Instead of the 7 × 8 inch truss timbers we would use two wire cables made of galvanized wire, seven strands, and doubled. While we would use a little heavier posts in the stables, the posts of the superstructure would contain only about one-half as much material, but this, too, we would prefer of different shape. In place of the 7 × 8 inch we would use two 2 × 8’s, and instead of the beam we would prefer the arch and the angling purlin posts, and thus have the interior entirely free from all timbers.
Is the Barn Frame of Sufficient Strength?
After 20 years’ experience in building barns without the cross beams it would require peculiar conditions to induce us to use them, for they are continuously in the way, both when storing away hay or grain and when getting these out again for the thresher or for the feeding of stock. The upper portion of the frame submitted by “C. G.” does not show any braces, and we are at a loss to know if there is to be none, or if these were omitted because it is not that portion of the structure that is under consideration. Let me say, however, that that is one of the most prevalent mistakes in the construction of a barn. There are too few braces, and the first baby tornado that happens to pass that way will “lay it out in fine shape.” While we use plenty of braces, they are usually only 2 × 6 inches, and so do not take timber very rapidly. The geometrical triangle is the strongest figure one can secure, and it is with that idea always in mind that we do our barn work.