Log Cabin Floors And Roofs

IF YOU do not want a cabin floor that resembles a hammock, or a roof that might be a sieve in disguise, avoid hasty and careless construction when you come to these important parts. Much that is said con­cerning floors and roofs for log cabins can be applied to other types of cabins, and to lodges, bungalows; tourist homes, and similar structures.

The typical cabin floor consists of tongue-and-­groove flooring laid on joists made either of logs or dimensioned lumber 2 in. thick. The installation of log joists is properly a part of sill building, and should be completed before the wall proper is erected. De­partment of Agriculture suggestions for log joists call for spacing on 2-ft. centers. When this spacing is used, the following sizes are specified for various span's: 12-ft. span, use a log 6 in. in diameter; 16-ft. span, 8 ­in. log; 20 ft. span, 9- to 10-in. Avoid longer spans if possible, because of the danger of sagging. There will be some natural settling or sagging of the log for any span. Some cabin builders compensate for this by hewing the log on top so that the floor is about 2 in. higher in the center, sloping gradually to the edges at the ends of the joists. Center piers and a beam running the length of the cabin (at right angles to joists) will add rigidity.

Strong construction demands that the joist ends be tied into the sills by proper joints. One of the simplest and strongest methods, and one that was used widely by pioneer builders, is to lay the joist ends on the sills and let them project a few inches beyond the outer wall surface, or until they are even with it. The sill is, of course, hewed flat on top. The bottom part of the joist, where it rests on the sill top, should be hewed just enough to prevent rocking. No more wood than absolutely necessary should be cut away, or there may be danger of splitting. A floor, you know, may be called upon to support a great weight. When log joists are used, the weight of the logs themselves amounts to no small figure. Fasten the joist end to the sill by boring a 1-in. hole through the two parts and driving into it a steel or wood pin; or a 40- or 6o-penny spike can be used, the hole being then bored half way through the joist end, and the spike driven the rest of the way with the aid of a steel bar used like a punch.

After all the joists have been fastened to the sills in the manner described, the cabin structure will resemble a grating with the two sills, extending along the longer sides of the cabin, serving as a framework for the cross-bars or joists. The first logs across the cabin ends can be laid either before or after the joists are in place. Usually it is preferable to set the joists first, so that the end logs will not be in the way, if con­tinuous sills are not used.

The diameters of these end logs, together with the type and degree of notching, will determine the space between each sill log and the next side-wall log above it, Usually this space can be made so wide that only a small amount of notching will be necessary along the under side of the second log, at the points where the ends of the sills occur. Chinking, possibly with the use of stones in addition to clay or mortar, will take care of the intervening space. It is not important for the top surface of the joists to be even with the tops of the sills. The joist tops are, however, hewed slightly flat, and all irregularities removed so that the floor boards will lie flat.

If the projecting of joist ends through the cabin walls is not desirable, the construction can be varied enough to overcome this. The method can be as de­scribed, with the difference that the joists are cut to such length that their ends will come about midway across the sills. Then the log directly above them is notched only halfway across its diameter—just enough to clear the joists. Subsequent chinking will conceal the ends of joists completely, and protect them from the weather. The notching of the top logs can be done with a 2-in. chisel and mallet or hammer.

A third method of attaching joist logs to sills makes use of a relatively difficult joint in which the ends of the joists are mortised into the sills, as shown in the drawings. Each joist end is cut to form a tenon, and a corresponding notch is made in the sill with a wide chisel. A hole is bored through the end of the tenon and into the sill, to receive a pin. The chief objection to this form of joint, according to veteran cabin builders, is that the forming of the tenon, which reduces the diameter of the log at that point, makes the log weaker and likely to split at the base of the tenon if the load becomes too heavy. Tops of joists are even with the sill tops, in this construction.

The scarcity of logs in some localities, and the fact that sawed lumber frequently can be obtained cheaper than logs, may make it advisable not to use log joists. Timber joists 2 in. thick and spaced 16 in. apart should, according to government experts, be 2 in. wider than the diameters specified for the logs. It is not necessary to do any notching or make fancy joints to fasten sawed joists to the log sills. Flatten each sill on the inner side as well as on top. Then spike a 2- by 6-in, board to it, extending it for the full length of the wall. The upper edge of this board should be approxi­mately even with the top surface of the sill, although it makes no difference if it is not. Next spike a 2- by 4-in. board to the 2- by 6-in. plank, with the upper edges of the two pieces even. The ends of the joists which are cut to fit snugly between the sides of the logs directly above the sills, rest on the ledge formed by the 2 by 4 and the 2 by 6. Toe-nail the joists to the other planks, and if possible to the logs. Further rigid­ity is produced by bridging the joists every 8 or 10 ft. of their length. This consists of cutting 1 by 4-in. strips of wood to such length that they will extend from the top edge of one joist to the bottom edge of the next one, the ends resting against the joist sides, where they are held by nails. Two such braces are employed at each point, forming an X. This row of X's extends for the full length of the floor.

Another way of setting dimensioned joists, and a more solid way than that just described, is to notch the sill logs to receive the joist ends, just as if tenoned logs were used. Do not cut tenons on the joists, but let them remain their full diameters and cut away the log above, if necessary. The notches should extend about one-third or half the distance across the sills. When this construction is employed, the load of the floor bears directly on the sills, instead of being trans­ferred from the joist to the sills through spikes. For this reason, the second method is better than the first even though it does involve additional work. If a bor­ing machine is available, the recesses for the 2-in. timbers can be made quickly with the aid of an auger bit of sufficient width. The so-called 2-in. boards pro­curable at lumber yards are more nearly 1 ¾ in. thick, for the dimensions are figured when the lumber is sawed and before it is planed.

After the joists are in place, the walls up and the roof completed, the floor can be laid. You can use standard 1 by 4-in. or random-width 1-in. flooring, tongued and grooved so that the edges fit together snugly. Pine, redwood, cypress, or similar low-cost wood is suitable. The boards are fastened to the joists by driving nails at an angle through the tongued edges. The next board covers the nail head. When log joists are used, an 8-penny flooring brad should be employed. With sawed timber joists, the 6-penny flooring brad is large enough, for there is no sapwood that must be penetrated before the more durable heartwood is reached. The floor can be varnished, either with or without staining; or it can be stained, shellacked, and waxed.

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How To Build A Log Cabin