Almost any variety of wood will suffice for the frame of the house, provided it does not twist and spring out of shape too much before or after it is put into the building. Since the sills are to be placed on solid, continuous walls, they need not be large. The only objection to box and small sills is that they may allow too easy access of air and rodents from the walls of the rooms to the cellar, and vice versa, unless the spaces above the sills and between the studding are bricked in as high as the top of the first tier of joists. A rough floor laid before the upright studding is placed is shown in Fig. 54. This first floor should be laid diagonally, for the one which is laid immediately upon it should not be placed either parallel or at right angles to the boards of the first floor, or parallel with the joists. A little reflection will reveal the reasons for all this.

Joists should be bridged. Fig. 55 shows the more common method of bridging. The joists may be 2 × 8 in small, inexpensive houses, and 2 × 10 or 2 × 12 in large ones, bridged once in a 12-foot span, twice in a 16-, and three times in an 18- or 20-foot span. The bridging is of the utmost importance and should never be omitted, as it serves to strengthen the floor joints and prevents the disagreeable trembling of the floors so annoying in many of the older houses.

The studding for a balloon frame is either 2 × 4, 2 × 5 or 2 × 6, and the length desired. The 2 × 4 studding are too light for an ample two-story house, and they do not give enough thickness of wall for the most desirable window- and door-jambs. The doors are not held firmly in place, and when they are closed quickly by the wind or by children, the plastering is injured. Studding 5 inches broad, fortified by outside diagonal boarding (Fig. 56), gives the ideal conditions unless the house is unusually large, in which case the studding should be 6 inches broad. The diagonal boarding costs a trifle more in material and labor than the horizontal, but it is so much superior that the extra expense may well be incurred. Every board forms a double brace, one where nailed to the studding and one where the siding or “clap boards” are nailed to the rough boards and the studs. Nothing has yet been discovered which is so satisfactory, and which gives such strength and protection to the frame as does this preliminary diagonal boarding, covered with paper. When completed it forms a wall open enough to prevent dry rot and tight enough to prevent the entrance of wind.

The second-story joists rest on stringers or light girders 1 × 5 inches, as shown in Fig. 57. If the girder is set flush with the inside of the stud, A, the laths must lie directly upon the face of the girt. This gives no room for the mortar to form clinches behind the lath. This 5-inch girder swells when the mortar is put on and shrinks when it dries, which may result in a crack in the wall in the angle near A. Since, by reason of faulty construction, there are no clinches behind the lath, the plastering becomes loosened, and this is likely to be the beginning of serious trouble. If the girder is let in so that its face is not flush with the inside of the stud and then furrowed out with small pieces of lath, the effects of the shrinking of the girder will be obviated and room will be left for clinches behind the lath.

In windy, cold climates, where lumber is at all abundant, a second boarding may be placed inside, covered with paper and furrowed out with a single thickness of lath to allow, as in the former case, the formation of clinches. There is no objection to boarding horizontally on the inside, if the outside has been boarded diagonally. The term “rough boarding” has been used, but it should be said that the boarding which forms the first covering, sometimes called sheathing, should be brought to uniform thickness and matched or rabbeted.

Wherever greater strength of wall is desired than can be formed by a single 2 × 5 studding, as at the corners, or by a single 2 × 10 joist, as where partitions are to be placed, it is better to spike two or more pieces together than to have pieces sawed of the dimensions desired. These made-up pieces or timbers are stronger than solid pieces of the same character and dimensions, since the continuity of the cross-grain of the wood is broken in the made-up pieces. In the construction of large bridges the timbers, where exposed to the weather, are made up of smaller timbers, since they are then not only stronger but more durable and less subject to dry rot than if they are solid (Fig. 58).

Plates are made up of material 2 inches thick and as broad as the studding is wide, doubled, with joints mismatched. This most valuable principle of building up timbers of several thin pieces is a somewhat recent practice. Where very large timbers are required, as in trussed or self-supporting roofs, the timbers of which are not exposed to view, they are frequently made up of boards 1 inch thick and as broad as the vertical dimensions desired. This method is sometimes used in constructing timbers for both houses and barns (Fig. 59).

Roofs of houses are, of necessity, extremely variable, as the house is not planned to suit the roof, but the roof to suit the house. Flat metal roofs of all kinds should be avoided, as far as possible, on the farm house, however well they may be adapted to buildings in the city. Metal roofs are not objectionable in themselves, but only when they are laid flat on farm houses.

The pitch of roofs, like their shape, is also variable. Nothing below one-third pitch should be used except for special conditions. In Fig. 38, page 127, is an illustration of the common pitch of roofs in fashion fifty years ago. Some roofs were even flatter than the one shown. The fashion now is to construct house roofs with nearly or quite half pitch. While steep roofs are desirable if made of wood, there is some danger that the change from the nearly flat roof to the steep one will be carried too far (see Fig. 13, page 95). Various pitches of roofs are shown in Fig. 61. Steep roofs do not require as strong rafters, thrust less upon the plates, are more durable, and are less likely to leak than flat roofs.

Since roofs are of various pitches, they require rafters of various lengths and bevels. Farmers and many carpenters have much difficulty in getting the length and bevels of both rafters and braces. Most carpenters’ squares have so-called brace rules stamped upon their tongues.[3] These give the length of the brace for the shorter and more common runs,[4] but they do not give the angles of the ends of the brace. Then, too, the length is given in inches and hundredths of inches, and carpenters’ squares are not divided into hundredths, so this complicated brace-rule is as useful as a steam whistle on an ox-cart.

The methods by which the length and bevels of any member of a frame which departs from any other member at an angle are so easily understood that the wonder is that all are not familiar with them. For a simple illustration, let it be supposed that rafters for a building 18 feet broad, with one-third pitch, are to be laid out (Fig. 62). The rafter, R, takes the form of a brace. The run is 9 feet horizontally or half the width of the building, and 6 feet perpendicularly. If the square be laid upon the stick designed for the rafter, as 6 is to 9, one side of the square will give the shorter and the other the longer angle or bevel (Fig. 63). If the square is laid on 12 times at 9 and 6 inches, it will give the length of the rafter, for 12 times 9 is 108, half the width of the building, and 12 times 6 is 72, the height of the peak above the plates. If the square is laid on 18 × 12 inches, the proportion is preserved, and hence the angles; the square would only have to be laid on six times.

Consider a building 20 feet broad and 6 inches above one-third pitch. The half of 20 feet equals 10 feet, or 120 inches. Seven feet 2 inches (86 inches) is the height of the peak above the plate. It is quickly seen that this problem, like the other, can be solved in more than one way. If the long end of the square is laid on at 20 inches and the short end at 14¹⁄₃ inches, and this is repeated six times, both the bevels and the length will be secured (Fig. 64), for 6 multiplied by 20 equals 120 inches, half the width of the building, and 6 multiplied by 14¹⁄₃ equals 86 inches, the height of the peak. Or the long end of the square might be laid on at 24 and the short end at 15¹⁄₅ five times, but squares are not marked in fifths of inches, hence the previous method would be best.[5] The same results would be reached by laying the square on at 15 and 10³⁄₄ inches; eight steps would then be required instead of six. The longer and fewer the steps within the limits of the square, the better.

If it is desired to cut a brace 3 × 4 feet run, 3 steps, using the lengths 12 and 16, will give both the length of the brace and the bevels (Fig. 65). Take a rafter which has a projection requiring a notch to be cut in the lower side, and the same rule will apply. The line A, Fig. 66, is horizontal and the face of the plate is perpendicular; therefore, the line B must be at right angles to A. The only thing now to be determined is how deep the notch shall be, for it is evident that if the line A represents the long end of the square and B the short end of the square, the notch will fit the plate.

That part of the rafter which extends over the building may be reduced in size, but usually it is well to leave it entire (as in Fig. 67) if the house is large. If the lower end of the rafter should appear too heavy, it may be treated as in Fig. 68. The bevels at the ends of the rafters are the same as at A and B (Fig. 66).

The outlines of a story-and-a-half house, which form is most undesirable for various reasons, are shown in Fig. 69. The chambers cannot be well lighted or aired. The outlines of the room interfere with the placing of furniture, and such chambers are far more uncomfortable in warm weather than are those in two-story houses. It will be seen that the collar-beam, C, must be placed so far above the foot of the rafters in order to get a fair height of ceiling, that it has little binding power, and that the building cannot be tied together at the plates in the center, since the tie would interfere with the door in the cross wall. It will also be seen that the second-story joists are so far below the plates that their power to hold the building together is small. Many of the one-and-a-half-story houses have “sway-backed” peaks because of this faulty construction. (See Fig. 35, page 124, broken-back house.) If story-and-a-half houses must be built, then they should be covered by roofs having at least one-half pitch, in which case the collar-beams could be placed relatively lower and the thrust on the plates would be very much diminished by the steeper roof (Fig. 70). One-, two-, three- or more storied houses are easily and certainly prevented from spreading since one tier of joists always coincides with the foot of the rafters, to which they can be securely fastened. Fortunately, the story-and-a-half house is less constructed than formerly.