This section is from the book "Cyclopedia Of Architecture, Carpentry, And Building", by James C. et al. Also available from Amazon: Cyclopedia Of Architecture, Carpentry And Building.
When the approximate position of the structure has been decided upon, the next step is to "stake it out," that is, the position of the corners of the building must be located and marked in some way, so that when the excavation is begun the workmen may know what are the exact boundaries of the cellar. This "staking out" should always be carefully attended to, no matter how small the building may be. In works of importance it is best to have the work done by an engineer, but on small work it is customary for the contractor or the architect to attend to it. It is well to have at hand some instrument with which angles can be accurately measured, such as a transit; but the work can be done very satisfactorily with a tape measure and a "mason's square." This simple instrument is composed of three sticks of timber nailed together as shown in Fig. 32, to form a right-angled triangle. It is important that the tape used should be accurate, a steel tape being always preferable, and that the mason's square should give an exact right angle. A mistake in the staking out may cause endless trouble when the erection of the building itself is begun, and it is then too late to remedy it.
There are several different lines which must be located at some time during the construction, and they may as well be settled at the start. These are: The line of excavation, which is outside of all; the face of the basement wall, inside of the excavation line; and in the case of masonry building, the ashlar line, which indicates the outside of the brick or stone walls. In the case of a wood structure only the two outside lines need be located, and often only the line of the excavation is determined at the outset.
Fig. 32. Mason's Square.
The first thing to do is to lay out upon the ground the main rectangle of the building, after which the secondary rectangles, which indicate the position of ells, bay windows, etc., may be located. Starting at any point on the lot where it is desired to place one corner of the building, a stake should be driven into the ground and lines laid out parallel and perpendicular to the street upon which the structure is to face. At the ends of these lines, which form sides of our rectangle, the lengths of which are determined by the dimensions of the building, other stakes should be driven, which define the direction and the length of the building. The exact location of the ends of the line may be indicated by a nail driven into the top of each stake.
After these lines have been thus laid out, others may be laid out perpendicular to them at the ends, with the aid of the mason's square and the tape measure. The accuracy of the right angle may be checked by the use of the "three-four-five" rule. This rule is based upon the fact that a triangle, whose three sides are, respectively, 3, 4, and 5 feet long, is an exact right-angled triangle, the right angle being always the angle between the 3-foot and the 4-foot sides. This fact may be proven by applying the well-known theorem, which states that the length of the hypotenuse of a right-angled triangle is equal to the square root of the sum of the squares of the other two sides. The rule may be used as follows:
Fig. 33. Diagram Showing Wrong Ground Layout.
Fig. 34. Batter Board to Indicate Layout.
Lay off on one of the side lines already laid out on the ground any multiple of 3 feet, as 9 feet or 12 feet. On the other line, presumably at right angles to the first one, lay off the same multiple of 4 feet, as 12 feet or 16 feet. Now a straight line measured between the points so obtained, should have a length equal to the same multiple of 5 feet, as 15 feet or 12 feet. If this is not found to be the case the angle laid out is not an exact right angle, and instead of a rectangle we have a parallelogram as shown in Fig. 33. This will not do at all, and the inaccuracy must be corrected. It is possible to lay out the right angle in the first place by this same method, using two flexible cords, respectively, 4 feet and 5 feet long. The end of the 4-foot cord should be fastened at the end of the side line of the building, and the end of the 5-foot cord should be fastened on this same side line, 3 feet away from the corner. When the loose ends of both cords are held together, and the cords are both drawn taut, the point where the ends meet will be a point on the side line of the building perpendicular to the first side line. It is evident that this point must be just 4 feet from the corner, and that the distance between it and the point on the other side line, 3 feet from the corner, must be 5 feet.
After all the corners of the building have been located, their position should be indicated by the use of "batter boards." One of these is shown in Fig. 34. It will be seen that it consists of a post A, which is set up at the corner, together with two horizontal pieces BB, which extend outward for a short distance along the sides of the rectangle that has been laid out. The horizontal pieces may be braced securely as shown, and the whole will be a permanent indication of the position of the corner. Notches may be cut in the top of the horizontal pieces to indicate the position of the various lines, and cords may then be stretched between the notches from batter board to batter board. These cords will give the exact location of the lines.
Fig. 35. Extra Strong Type of Batter Board.
Another way to indicate the position of the lines is by driving small nails into the tops of the batter boards instead of cutting notches in them; but nails may be withdrawn, while the notches when they are once cut, can not easily be obliterated.
Batter boards should always be set up very securely, so that they will not be displaced during the building operations. If there is danger that the form of batter board shown in Fig. 34 may be displaced, because of the large size of the structure and the length of time during which they must be used, the form shown in Fig. 35 may be substituted. Two of these at right angles to each other must be placed at each corner.
HOUSE IN THE WHITE MOUNTAINS, NEW HAMPSHIRE.
The Boulders, which are Plentiful in this Region, have been Used to Good Advantage.
HOUSE NEAR PHILADELPHIA, PA.
It is Verily a Part of the Landscape.