Putting in Foundations
The following data have been compiled and the drawings made by Mr. George W. Repp, a Chicago architect, and are based on the most widely followed building practice.
There is no intention of trying to inform the master mason or the master carpenter about his craft with which he is perfectly familiar, but to show the master carpenter builder the best methods of handling the brick problems that may confront him in solid brick, hollow tile, and veneer wall construction. A glossary of technical terms will be found at the close of this volume.
Footings
Whatever type of construction is chosen, solid brick, hollow tile, or veneer, it should rest upon a solid brick foundation. In the majority of cases, where soil conditions are favorable, the brick foundation walls of moderate sized houses do not need a footing except at points bearing concentrated loads. Naturally, the excavation should be carried down to good solid earth, free from loose, spongy soil or filled-in ground which might later permit sufficient unequal settlement to result in serious cracks throughout the wall of the house. Where conditions seem to require a footing, it may be either of brick laid in good cement mortar (Fig. 1) or of concrete as shown in our working drawings, and should be strengthened at points of special bearing stress. Which footing is chosen will depend largely on convenience of getting local material and labor. The bottom of the foundation wall or footing must always be below frost line which, of course, varies in different sections of the country; and this rule applies as well to all brickwork outside of the foundation wall proper.
Drains or Drainage
Where the conditions of soil require, porous tile with open joints should be laid around the base of the foundation wall, not above the level of the basement floor nor below the bottom of the wall or footing, and slightly pitched to a point where it may be connected with the sewer or some natural outlet. Where this tile is laid in loose sandy Soil, the open joints should be wrapped with building paper to prevent the sand from clogging the drain. In heavy clay soil, the tile should be covered to the depth of about a foot with crushed stone to prevent packing of clay around the tile.
The Wall
Foundation walls, technically speaking, are those walls below the grade line of the building that support the super-structure. Similar walls around areas are termed retaining walls and are not properly a part of the foundation. The thickness of foundation, as well as other walls for different structures, is usually established by ordinance in cities and towns; but, where there are no ordinances on the subject, a brick foundation wall of 12 inches, for two-story buildings, or one of 8 inches, for small one-story buildings, conforms to good practice.
The Bond
The foundation wall should be built of a hard-burned common brick, and laid in Common Bond (See Fig. 47), with a good cement-lime mortar, starting at the bottom with a header course. As the headers, which serve as transverse bond, are not long enough to extend through the entire thickness of the 12-inch, as they do through the 8-inch wall, the header courses in the 12-inch wall very naturally cannot be on the same level at the front and back of the wall. In the bottom course, the header row is laid inside and the stretcher row outside, while in the next course above the position is reversed, and so on wherever the bonding header courses come.
Laying the Brick
The first course of brick is well bedded in mortar on the footing or the solid ground, as the case may be. At the corners and at proper intervals along the wall where necessary, a few brick, four or five courses high, are laid up in the advance to serve as leads or starting points for the bond and supports for the line which guides the mason to the proper level and alignment of the brick. The mortar is well spread with the trowel along the top of the brick course, and the brick to be laid is firmly pressed down on this mortar bed next the lead. The mortar thus squeezed out of the joint is cut off by the trowel and scraped on the head of the next brick to be laid which is then pressed on the mortar bed and shoved against the brick just laid, so as to squeeze mortar into the bottom of the vertical or head joint which is then thoroughly filled from the top by slushing with mortar. The stretcher courses for structural reasons should be well slushed with mortar between the front and back rows or tiers of brick, laid to break joint.
As the work progresses, the joints on the inside face of the basement wall should be neatly struck, while the outside joints should be cut flush for receiving a waterproof coating. The inside joints are struck by running the point of the trowel, held firmly at an angle, along the upper or lower edge of the brick, thus making a smooth beveled joint (See Fig. 57).
The wall should be widened where indicated on any plan to serve as a foundation for the fireplace, and should be built hollow to provide for an ash pit. Where other chimneys occur, the wall at their base should be corbeled out to serve as a support for them.
Scaffolding
After the wall has risen four or five feet, scaffolding is erected to carry on the upper portion. The scaffolding, necessary for the usual house, or other small building, consists of a series of rigid horses or trestles, approximately 5’-0” wide and 5’-0” high, on which are placed a half-dozen 2” × 10” planks laid close. The joists for the floor above may be used for this planking and then lifted into place when the wall is ready to receive them, thus effecting a saving in labor. Care should be taken to keep the horses several inches away from the inside face of the wall, lest the jarring caused by bricks and mortar being deposited on the scaffold may push the green wall out of plumb. The scaffolding for the foundation wall may be dispensed with, if it is found more convenient to lay the upper portion of the wall from the outside.
Waterproofing
All brick foundation walls should be water-proofed on the outside except in gravelly, sandy, or very dry soil. In case there is danger of moisture rising in the wall by capillary attraction, the top of the footing should be water-proofed, before starting the walls, by a course of slate well bedded in mortar or by a strip of composition roofing. In wet locations, it would be well to carry the waterproofing under the basement floor also. For waterproofing the foundation walls, in slightly wet soils where the drainage is fair, a coating of one-half inch cement plaster may be applied to the outside surface of the brick as the wall is carried up. This plaster should be composed of one part Portland cement and two parts clean, sharp sand. The possibility of settlement cracking this cement coating makes it undesirable for use in heavy soils such as wet clay, or in low-lying land where the subsoil is likely to be wet. In such conditions, a coating of asphalt applied while boiling hot, thoroughly covering the brickwork, is very satisfactory. A less expensive though excellent waterproofing, which we suggest in our specifications, is made of three parts of tar and one of pitch. Tar alone is sometimes used, but is not recommended as it becomes brittle and is subject to cracks, similar to cement. Except in dry, warm weather, it is well to prepare the wall for the waterproofing by sizing or priming it with hot creosote, to overcome any dampness that might prevent the asphalt or tar-pitch from taking proper hold.