Part 2

When the type of window or door frame here described is used, neither outside nor inside casings, sometimes called wood trim, are required. The logs selected for the jamb material should be from 2 to 3 inches larger in diameter than the wall logs, in order to fit properly. Also, they will be much easier to work if well-seasoned (fig. 16).

If standard mill work frames are used, false side jambs of sawed material, usually 2-inch planks, should be fitted in the openings to hold the logs in place. For a wall made of 10-inch logs, a plank 2 inches by 10 inches should be used for the jambs and the standard frame fitted in place between them after providing the necessary allowance for the wall logs to shrink or settle. The head casing ordinarily will cover the space allowed for shrinkage.

Some kind of insulating material which will take compression, such as crumpled newspapers, asbestos wool fiber, or rock wool, may be used to fill the space over the head allowed for settlement. Insulating material must be installed loosely, so as not to take any weight as the headlog gradually settles.

For the log-type frame, copper or galvanized steel flashing should be fastened to the bottom of the cut in the top log, leaving the lower edge of the flashing free to slide on the face of the log head jamb. As the wall settles, the bottom of the flashing can be trimmed off if too much of the face of the head jamb is covered. This makes a weathertight joint and protects the insulating material with which the shrinkage space has been filled. See figure 17, Head section.

ROOF FRAMING

Roofs may be framed in several ways, depending upon the kind of material available and the appearance desired. The framing for a shingle roof, whether of sawed material or round poles, is done in the same way as that of a frame building. The top log on the wall may be cut with a flat seat for the rafters to rest upon, as at _Y_, in figure 18, _A_ or notched out to receive them as at _Z_ in figure 18, _B_. The gable ends may be run up with the logs, which is preferable for architectural appearance, or framed like the gables of a frame structure, and then covered with wood siding, shingles, or shakes (fig. 19).

The shingles may be laid over sheathing boards in the usual manner or on shingle strips placed across the roof rafters, parallel with the ridge and exactly spaced to receive them, commonly known as "barn-fashion."

The particular method to be followed in framing the eaves depends largely upon their projection. Where the effect of a considerable overhang is desired, an eave purlin log may be used to support the projecting shakes as shown in figure 19, _A_. To support 30- to 36-inch long shakes having a 6-inch lap, the log purlins should be spaced at approximately 24-inch intervals, as in figure 19. In regions of heavy snows, the eave log may be placed slightly forward to help support the overhang, or an additional eave log may be placed in position, as shown in figure 19, _B_. The gable logs should be run up at the same time as the roof logs, and both rigidly framed together.

Shake Roofs

It is often desirable to use hand-split shakes for the roof covering. These are usually made from cedar, but may be of any straight-grained wood, free from knots, which splits easily. First, the logs are cut in lengths of 30 to 36 inches and then the shakes are split off with a tool called a froe (fig. 20).

After the log cuts are set on end, the froe is held on the upper end of the block and then struck a blow with a wooden maul which causes a piece of the block or shake to split off. Being hand-split, the thickness varies somewhat; the minimum is 1/2 inch. A roof of thin shingles, lacking sufficient scale, is never as effective as a rough textured one, using 3/4- to 1-1/4-inch thick shakes, to harmonize with the sturdy appearance of the log walls. The width, normally 6 to 8 inches, is governed by the size of the blocks of wood and varies accordingly, while the length is governed by the spacing of the roof logs or purlins. Shakes are always laid on the purlins in single courses, lapping the sides 1-1/2 to 2 inches and over-lapping the ends at least 6 inches, as illustrated in figure 19. Nailing is usually done with six- or eight-penny galvanized box nails. Copper nails may be used for greater permanence. A good shake roof will not leak although from the inside of the building it may appear to have many holes.

The ordinary, uninteresting, straight-line effect at the butts may be broken up by staggering them from 1 to 2 inches, as is often done with shingles. This method produces an effect more in keeping with the log walls. Although involving greater care and additional labor it is preferable, from an architectural point of view, to the more common custom of laying them to uniformly straight lines.

At the ridge of the roof, where the shingles or shakes intersect, provisions must be made for weatherproofing. The shingled Boston ridge, comb intersection, or pole ridge, shown in figure 21 are practical and much more satisfactory from the standpoint of architectural effect than stock metal ridges, ridge boards, and other methods.

PARTITIONS

If the log building is to be divided into several rooms, at least two different methods may be used to construct the partition walls. If the log construction plan is to be carried throughout the structure by using interior log-wall partitions, these should be laid out and framed in, and the door openings cut in the same manner as previously described for exterior walls. If a log partition comes at a place in a cross wall where it is not considered desirable to have the log ends project into the room beyond the opposite face of the wall, they may be sawed off flush with the face of the cross wall, as shown at _X_, figure 22, Plan _A_. This will not weaken the joint since the logs are both pinned and locked in place.

Where frame partitions are used, they should be constructed as in a frame building. A gain or a 3- to 4-inch deep groove should be cut in the log wall into which the end studding of the frame partition is to be set (fig. 22, Plan _B_). The cut should be made in each log before it is placed in the wall. In no case should the studding at the ends of the partitions be nailed to the log walls which they intersect in order not to interfere with or be affected by their shrinkage and settlement.

FLOORING

A subfloor should be laid first using shiplap or sheathing. Over this a finished floor of such hardwoods as maple or oak, or the harder softwood species such as Douglas-fir, western larch, or southern pine, may be laid. Vertical grain and flat grain may be had in both softwood and hardwood, but the vertical grain shrinks and swells less than the flat, is more uniform in texture, wears more evenly, and the joints open much less. Finished flooring consists or tongue-and-groove material of various thicknesses and widths.

Despite a slight tendency to splinter and wear irregularly over a period of years, plain wide planking of random-width boards makes an appropriate floor for a log building. An attractive effect may be had by using screws instead of nails, countersunk to a depth of 1/2 inch and concealed by inserting false wooden dowels glued in place as shown in figure 23, _B_. Keying the boards together with wood keys, at random along the edges, adds to the attractiveness of the flooring.

INTERIOR WOOD FINISHING

Hanging doors and windows, and many other customary details of building construction should be done in the usual manner in building with logs. Whenever cupboards or other built-in units are constructed, they must be framed to be independent or entirely free of the log walls, like the furniture. However, such fixtures as lavatories may be attached to two adjacent logs without any subsequent structural complications.

CALKING

When round logs are laid up in a wall there is always an opening between them unless they are grooved on the under side to saddle the one below, as described later under chinkless log cabin construction. In exterior walls, this opening, or crack, must be closed in order to make the structure weathertight. There are several methods of doing this. If the logs are reasonably straight and uniform in size and the corners carefully made, the opening between them will be small, often barely perceptible. When this is the case, the openings should be filled with some sort of calking compound applied with either a pressure gun or a trowel (fig. 24).

In recent years several kinds of calking material have been put on the market. They are applied best with a gun having a pressure-release trigger whereby the calking compound is forced through a nozzle made in various shapes and sizes to meet different requirements. These calking compounds are not adversely affected by heat or cold, retain their natural flexibility, and have an adhesive property which causes them to adhere to the surface to which they are applied.

A good plastic compound will adhere to the logs under all conditions and can be patched easily by simply applying more material. A black fiber seal is not objectionable and, at the same time, gives a practical finish. The seal should be applied to both sides of the exterior and interior log walls, producing an almost hermetically sealed building. When applied with a pressure gun having a 3/8-inch nozzle, 1 gallon will fill about 300 linear feet of opening. If applied in cold weather, the material should be heated to a temperature of 60°F.

CHINKING

When using logs that are somewhat rough and irregular in shape, the resulting space between them may be so large that the calking material cannot be used satisfactorily to fill the opening. In such cases, it will be necessary to insert "chinking," which usually is applied to the interior and exterior walls in one of two ways:

1. _Split chinking._--Segments of a log are split out in sizes which fit the opening and, after being carefully shaped with the ax to make a tight fit, are securely nailed in position. This kind of chinking requires considerable work and patience to secure a good appearance.

2. _Pole chinking._--Small round poles may be used to fill the openings (fig. 25). Usually they are cut in sizes and lengths to fill the opening from wall to wall. This sort of chinking may be applied rapidly to either inside or outside walls and makes a neater job than the preceding method. Unless the logs are thoroughly seasoned these small poles sometimes have a tendency to pull away from the nails. When the chinking has been completed, the openings will have been reduced sufficiently in width to allow the calking material to be applied successfully.

It is always a serious problem in log construction to devise a practical method for permanently fastening the plaster daubing in place on both inside and outside walls. In some instances, shingle nails may be driven into the logs 2 to 3 inches apart for the full length of the opening or 2-inch wide strips of metal lath may be used and the plaster applied to fill it. Cattle hair may be added to the plaster to increase its adhesive consistency and thereby hold it more rigidly in place. Sometimes, wood strips are nailed on the lower log to hold the plaster in position, as shown in figure 26, but they are unsightly.

CHINKLESS LOG CABIN CONSTRUCTION

Chinkless construction, associated with the building of log structures in Scandinavian countries, eliminates the chinking and mudding so prevalent in many log buildings. It consists of grooving the under side of every log in each tier so that it saddles the log beneath, making a close joint for its entire length. The groove is marked by a tool which, for convenience, may be called a cabin scribe or a drag (fig. 27).

_Directions for chinkless log cabin construction._---Mark and cut out the notch just as is done for a round-notch corner. Next, dog the log in place and scribe, making the additional mark shown by dash line (_X_, fig. 27). Then, cut to line and, finally, drop log in position.

The scribe is 12 inches long, made preferably of 3/8-inch square steel or iron bent in much the same manner as the spring in a steel trap; the two ends are turned down about 1-1/2 inches like two fingers, diverging to about 3/4 of an inch at the points, and then sharpened with a flat surface on the inside of the point toward the loop. The loop should be hammered out thin to provide sufficient flexibility to allow the points to spread or close easily. A ring is welded around the two halves of the tool which, when slipped up or down, makes it possible to adjust the points and thereby prevent any further spreading while the tool is in use. A link from a small chain, placed over the legs before the points are turned, will serve the same purpose and, to prevent the points from springing together, a small piece of wood may be forced between them.

To fit a log, first frame it at the ends and then fit it down to within about 2 inches of the lower log where the opening is the widest It is difficult to do a good job of scribing when the logs are too close together. The scribe must then be adjusted at the point where the opening is the widest so that, when holding the tool parallel to the opening, the lower point of the scribe will ride on the surface of the bottom log. By exerting sufficient pressure, the upper point will score the top log. Repeat this operation to score the upper log on the other side. The corner tenons must be marked likewise. Next, turn the log over, work the tenons down and then cut a =V=-shaped groove to the marked lines in the remaining portion of the log, using a double-bitted ax. This groove should be cut deep enough along its center to permit the outer edge of the groove to rest continuously on the lower log. By removing the least amount of wood to make the smallest possible groove, the closest fit is obtained with the least effort.

The principle of the scribe is based on parallel lines, and it can readily be seen that if there is a hump on the lower log there will have to be a gouge in the upper one. When the work is done carefully, the space remaining is negligible. Where an airtight wall is desired, a strip of plumber's oakum should be laid on the bottom log before the upper log is dropped into place. If this material is not available, dry moss is a fairly practical substitute.

Milled-Log Construction

Sometimes it is feasible to take advantage of a portable mill to face the logs on three sides rather than to hew them by hand. The level beds seat the logs so well that calking is minimized, the smooth interior surfaces permit of easy finishing, particularly where wood wainscoting or plaster is used, while the round-log exterior effect is undisturbed, except where the logs project at the corners. Figure 28 illustrates a structure built in this way.

HEWING TIMBERS

The facing or hewing of round timbers to obtain one or two sides surfaced flat for framing purposes, as shown in figure 29, requires considerable skill in the use of the ax and broadax. There are, however, a number of mechanical aids (fig. 30) which should be used by anyone undertaking log construction in order to simplify the work as much as possible. The carpenter's spirit level, the steel square, and chalk line and chalk are necessary for laying off the lines to be followed in hewing timbers. In framing logs they should be laid up on skids, or sawhorses, dogged fast in place with iron dogs, and the dimensions laid off on each end of the log with the level and square to insure that the lines are parallel to each other. Then, with the chalk line, carefully snap lines on the side of the log connecting corresponding points at each end. For squaring the ends of a log and cutting pole rafters, use the miter box to guide the saw. To measure lengths accurately the steel tape, or a board pattern cut to the exact length, may be used.

FIREPLACE FRAMING

The living-room fireplace, invariably the most prominent interior feature, harmonizes best with a log interior if built of stone and provided with a crude log shelf. The fireplace itself may be either the traditional masonry type or the more modern metal-lined one equipped with a heatilator.

The masonry of the fireplace and its chimney should always start on solid earth, below the frost line, like the foundations of the building itself. Masonry does not settle, unlike the surrounding log construction. Consequently, it is recommended that a self-supporting log framing be built around and entirely free of the masonry of the fireplace and chimney, as illustrated in figure 31. The opening should be framed in the same way as window and door openings. The fireplace and chimney masonry should not be erected until the opening has been framed for it. Upon completion, the intersection between the stone and wood should be thoroughly calked to make an airtight, weatherproof job. This method allows the wall logs to settle, because of the unavoidable shrinkage, without structural failure.

In building an ordinary fireplace, the firebox and inner hearth should be made of firebrick to withstand intense heat and the various parts proportioned in accordance with standard practice to insure efficient operation.[1]

[1] For this purpose the following publication will be found useful: Farmers' Bulletin 1889, Fireplaces and Chimneys.

The heatilator is a built-in recirculating steel unit consisting of metal sides and back to form a heating chamber, adjacent to the fire pit, which draws cold air through a register at each side near the floor and after the air is heated ejects it through similar registers above. It should be installed in conformity with the manufacturer's directions, taking care to select a stock-size unit suitable for the dimensions of the fireplace opening and to erect the surrounding masonry accordingly.

OILING AND PAINTING

After all the openings have been properly calked and the logs brushed clean, it is often desirable, although not absolutely necessary, to treat the log surfaces with some sort of preservative material. Logwood oil is excellent for the exterior. The colorless variety is preferable in most cases but, if some color is desired, add just enough burnt umber, or raw sienna paste, to give the proper shade. For interior finish, apply a coat of clear shellac and then one or two coats of dull varnish. The trim can be treated in a similar manner to preserve the pleasing effect produced by the natural surface and color of the wood.

THE FINISHED STRUCTURE

Examples of modern log construction are shown in figures 32, 33, and 34. Early types of log structures are illustrated in figure 35.

FURNITURE

The matter of interior furnishings is always of great concern to those who build log cabins. Odds and ends or too many "what-nots" may prove to be misfits. Pieces of Early American design are perhaps the most appropriate ready-made furniture, but sturdy, rustic pieces yield the greatest satisfaction.

Many cabin owners have found a great deal of pleasure in making essential furniture, such as bunks, beds, tables, chairs, settees, and similar items. In the East, birch is preferred as a material, and in the West, lodgepole pine is most satisfactory. Other native species, however, will do just as well. In making furniture it is advisable to remove the bark from the logs because bark collects insects, causes the wood to deteriorate and eventually falls off, leaving imperfect, unsightly surfaces. Figures 36 and 37 show types of furniture suitable for log residences.

For rustic effects, the use of a stain of the following proportions gives a satisfactory appearance: 2 quarts turpentine, 2 quarts raw linseed oil, and 1 pint liquid drier, to which add 1/2 pint of raw sienna, 1/2 pint of burnt umber, and a touch of burnt sienna. The top surfaces of tables, buffets, chests, and rawhide seats should have two coats of spar varnish. Where countersunk screws are used in connection with a stain finish, insert false wood, dowel-like plugs in preference to plastic wood to conceal the screwheads.

Simplicity, both in construction and appearance, is the keynote for producing the most harmonious effects in furniture, in keeping with log interiors.

Chairs and Stools