A manual of face brick construction
Part 3
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.
SOLID FACE BRICK CONSTRUCTION
[Sidenote: Thickness of the Wall]
Where ordinances do not govern, the thickness of brick walls above the foundation may be 8 inches (two brick thick) for one or two-story small houses, except in the case of an unusually high gable where the first story wall should be 12 inches (three brick thick).
[Sidenote: Water Table]
At the grade line the face brick is started, sometimes with a rowlock course or a soldier course, set either flush with the outer surface of the foundation wall or, as usual, slightly projected, in which case it is known as the water table. On the other hand, the entire base or lower portion of the building from the grade to the first floor sometimes extends as a water table beyond the wall above. Figs. 2-7 show various ways of treating this portion of the wall which add to the interest of the brickwork.
The method of laying the face brick is substantially the same as that for the foundation wall except that much greater care must be taken with the bond and mortar joints on the surface of the wall. A description of various bonds and patterns will be found on pages 33-35.
[Sidenote: Building]
The method of bonding the face brick to the common brick backing follows the usual method Bonding means of headers every five or six courses, the headers in other than Common Bond, not used for bond, being cut in half. In the widely used Stretcher Bond where no headers occur except at corners, three methods of bonding may be employed. First, but only in case of walls 12 inches or more thick, the back corners of the face brick may be clipped so that the backing brick fit diagonally into the notches thus provided (Fig. 8). This sort of concealed bond is weak and should be avoided.
Secondly, the face brick may be tied to the backing by laying metal strips or wires, supplied by any material dealer, in the bed joints of face and backing brick (Fig. 9). Although this method is frequently used and in a way answers the purpose, we do not regard it as the simplest and best.
We recommend the third method which is a natural bond, thoroughly workmanlike and sound. Every sixth or seventh course, pairs of headers are laid with a tight buttered, and hence invisible, joint alternating with the stretchers. As the joint between the headers is hardly seen, the two headers give the appearance of a stretcher, so that the effect of the Running or Stretcher Bond is maintained (See Fig. 31).
[Sidenote: Backing]
The face brick are laid up five or six courses in advance of the backing and the joints on the face of the wall are finished (See Fig. 57) as the work progresses. On outside exposed surfaces, the struck joint should be avoided, and particular care should be taken in seeing that all head or vertical joints are thoroughly filled with mortar from bottom to top. Each face course should be started so as to care for the bond or pattern chosen, as well as for the transverse structural bond. The backing is then laid in the usual way, always, so far as possible, breaking joint with the face brick. No attempt, except where strength is specially demanded, should be made to slush the thin space between the front and back tiers of brick, as this space helps to make the wall drier and warmer. Wherever the common brick backing is to be exposed, the joints must be neatly struck as in the basement wall. At the close of the day's work, face and backing should be brought to approximately the same level and covered to protect the work from the weather.
[Sidenote: Treatment of Joints]
The brickwork should be stopped at the point where the first floor joists are to rest upon it, and care should be taken to have the top course perfectly level, so that the joists may be set without wedging or blocking. The joists set by the carpenter should have, at intervals of approximately six feet, wrought iron joist anchors solidly spiked to them, and extending into the wall. Great care should be exercised in placing these anchors as near the bottom of the joists as possible in order to lessen the strain on the brick wall, in case a fire causes the joists to drop.
For the same reason, the ends of all the joists, with or without anchors, should be beveled so that, in like conditions, the joists will readily fall out without injury to the wall. Fig. 10 illustrates the correct method of attaching the anchor to the joist. The dotted lines show how the joist would drop without damaging the wall. Fig. 11 shows the destructive effect caused by the anchor being placed at the top of the joist. The importance of these points cannot be emphasized too much as walls have had to be rebuilt which by proper framing construction would have stood intact. After the joists are placed, the brickwork is continued up between, and leaving a small "breathing" space around, them. The same method of joisting is followed at the upper floors.
If the lower part of a wall is thicker by a brick than the upper part, it should be carried up its full thickness nearly to the top of the joists Fire Stops where ft is stepped back to the inside face of the upper part, thus forming with the plastering a fire stop at the top of the joists, while a projection of a quarter brick length should always be provided as a fire stop at the bottom of the joists, as shown in Fig. 12. If the wall is the same thickness throughout, the brickwork should be corbeled out between the joists two inches, the full height of the joists, to form a fire stop as in Fig. 13. The object of the fire stop is to block all possible passage of fire from the space between the joists to that between the furring strips on the wall, or the reverse. Without these fire stops, a fire originating in the floor could communicate with the furring space on the wall above, or originating in the furring space could communicate with the floor. With the stops, the fire is confined to certain spaces and is retarded instead of spreading. These corbels also serve the wholesome purpose of checking vermin of all kinds from passage through the floor and wall spaces.
[Sidenote: Ceiling Lath]
Figs. 12 and 13 also show the proper way of placing the lath at the corner of the ceiling so as to take full advantage of the fire stops. The ceiling lath, usually placed first, should be started far enough away from the side walls so that when the side wall lath is placed tight, as it ought to be, against the underside of the floor joist, there will be space enough for the plaster to push through and form a key touching the bottom brick of the corbel. As the corbel by construction is necessarily the distance of a mortar joint above the bottom of the joists, the openings are thus completely sealed by the plaster key. In cheap speculative buildings, these fire stops are too often omitted or a pretext for them is resorted to by projecting only one brick at the top or bottom of the joists. This, however, is as good as no fire stop at all. Figs. 14 and 15 show the lath as they ought not to be placed and also how false corbeling leaves the passages really unstopped, thus defeating altogether the purpose of fire stops.
Masonry walls that are to be furred, sometimes have, as the work progresses, common wood laths laid in the joints of the brickwork on the inside face of the wall, about every seventh course, except over chimneys. The lath should be staggered so as to avoid two vertical lath joints in succession. These serve as nail holds for the furring strips as explained on page 24.
[Sidenote: Laying a 2-inch Wall]
Where local requirements demand a 12-inch wall, the method of construction is the same as in the 8-inch wall, except that two rows or tiers of backing brick, instead of one, are carried up to the advanced level of the face brick, leaving the thin spaces between the tiers of brick open as the best way of securing a warmer and drier wall. Of course, in the case of piers and points in the wall that carry heavy loads, all interior joints should be well slushed with mortar for evident structural reasons.
[Sidenote: Roof Plate Anchor]
Before the top of the wall is reached, the anchors for bolting down the roof plate should be placed and the brickwork carried up around them (Fig. 16). They should be made of half-inch bolts at least 12 inches long, with a tee or washer at the bottom and a nut and washer at the top, and should be set approximately every 6 feet along the wall. After the carpenter has placed the roof plate and before it is bolted down, the mason should bed with cement mortar under it.
[Sidenote: Nogging]
When the wall is finally carried to the top and the roof rafters set, but before the roof boarding is in place, the mason should fill in between the roof rafters with one tier of brick as shown in Fig. 16. This is called nogging. Its purpose is to block effectually the openings between the roof rafters and prevent the wind from entering the walls and attic. This adds greatly to the comfort of the house in cold weather. In warm climates nogging will be found unnecessary.
The Chimney
While the chimney may be made one of the most charming and effective elements of the house design, its structural and practical necessities are its most striking features.
The proper construction, size, and height of chimneys are of the utmost importance both for the successful working of the heating system and for the prevention of fires. The chimney may, though it need not be, a point of danger to the safety of the home. A little intelligent care in its construction will prove to be the best insurance. As a first precaution, all wood framing of floor and roof must be kept at least 2 inches away from the chimney and no other woodwork of any kind be projected into the brickwork surrounding the flues.
Chimneys should be tightly built of solid brick, have no openings except those required for the connection of the heating apparatus, and should always extend at least one foot above the highest point of the roof. In some cases, depending on local surroundings, it may be desirable to carry them somewhat higher. Those terminating below the level of the roof usually have poor draft because the wind, sweeping across or against the roof, may form eddies that drive down the chimney or check the natural rise of the smoke (Fig. 17).
[Sidenote: Flue Lining]
The flues of chimneys should not start from the bottom of the foundation but only about a foot below the first smoke pipe openings, and should be lined with terra cotta flue lining their entire height. Care should be taken in setting flue linings to be sure that the joints are well cemented and, at the same time, that all spaces between the lining and brickwork are tightly filled with mortar. Any openings in the joints of the tile lining, or even of the brickwork, not only check the draft but are a fire menace. Cement plaster should not be substituted for the flue lining as it is likely to crack and fall off, thus leaving the flue in a dangerous condition. However, where flue linings are not available, a strong smooth cement plaster may be used, in which case the chimney wall should be at least 8 inches thick.
Modern heating plants necessitate accurate construction of chimneys, and most manufacturers of heating apparatus nowadays recommend the area and height of the flue necessary for their installations. The following table will prove useful in considering the question of heating plant or fireplace, by showing the dimensions of flue linings to be ordered when the required area is ascertained.
Table of Commercial Flue Linings
_Outside Dimensions_ _Actual Inside Area_
8-1/2" × 8-1/2" 52 sq. in. 8-1/2" × 13 " 80 " " 13 " × 13 " 126 " " 13 " × 18 " 169 " " 18 " × 18 " 240 " "
[Sidenote: Offsets]
Where two or more flues are contained in one chimney, they should always be separated by a brick partition 4 inches thick, called a withe, and bonded to the outside brickwork as shown in Fig. 18. Chimneys should run as straight as possible from bottom to top, in order to secure better draft and facilitate cleaning. If, however, offsets are necessary from one story to another, they should be very gradual, never less than at an angle of 30° from the vertical. If abrupt offsets occur in flues, soot will soon be deposited, choking the flue and making cleaning almost impossible (Fig. 19). Care should be taken while the chimney is building that the bottom does not become filled with mortar or brick bats. At the bottom of the furnace flue in the basement, an iron cleanout door should be provided as a convenience for removing soot.
Chimneys erected on the interior of a building are apt to be more efficient because the warm air surrounding them facilitates the draft, while those located on the exterior naturally are somewhat affected by the cool air on the outside.
Angles, Bays, and Corners
All the houses represented in this book are designed without any obtuse or acute angled corners. If, however, you wish to erect a brick building with an angular corner or bay, specially shaped face brick for the purpose, called splay or octagon brick, may be obtained from the dealers or manufacturers. If for any reason these special shapes are not easily available, the angle may be formed by the use of standard size brick. The method shown in Fig. 20 is used only on cheap work and should be discouraged, for it leaves ledges for the lodgment of snow and dirt, decreases the thickness of the wall, and besides is rather unsightly. The better method, as shown in Fig. 21, also has the objection of forming ledges for the lodgment of snow and dirt, but it makes a wall of full thickness, and has been used by some architects in a very artistic manner. The best method of all, for treating these corners, is shown in Fig. 22. Standard bricks are used with the minimum amount of cutting. Fig. 23 shows a method of laying brick at an acute angled corner. It is simple to lay up, there is little cutting of brick, and it presents a better looking corner than one with a sharp angle.
Openings
Window sills in brick buildings should be of brick or stone. Cement, unless pre-cast, is not well adapted for the purpose. Brick window sills are preferable to stone for, besides adding a charming touch to the building, they are inexpensive since they are of the same material as the wall and placed by the same workmen who lay up the wall, thus obviating the necessity of additional labor to place the heavy stone. Brick for sills should be laid on edge and pitched approximately at an incline of 1 inch in 6 to shed the water. They should also project at least an inch beyond the face of the wall to form a drip, and be laid in rich cement mortar composed of equal parts of cement and sand, with joints well filled and finished with a hard smooth surface. Door sills may be of wood, brick, or stone. In case of a stone sill, it should be exactly the height of either two or three courses of brick.
[Sidenote: Window Frames]
The window frames are set by the carpenter on top of the sill in a thin bed of mortar. When they are leveled, plumbed, and braced, the brickwork is carried up around the jambs or weight boxes, as shown in Fig. 24, always making certain that the corner or jamb of the brick opening is perfectly plumb. Great care should be taken to fill solid with mortar the spaces between the brickwork and the window frame, to stop the wind.
Stock Window Sizes
_Double Hung Sash, 1-3/8" Thick_
_Glass Size, _Masonry D. S._ _Lights[A]_ _Sash Size_ Opening_
16" × 16" 2 1'- 8" × 3'- 2" 2'-0" × 3'- 6" 16" × 26" 2 1'- 8" × 4'-10" 2'-0" × 5'- 2" 22" × 20" 2 2'- 2" × 3'-10" 2'-6" × 4'- 2" 28" × 26" 2 2'- 8" × 4'-10" 3'-0" × 5'- 2" 30" × 24" 2 2'-10" × 4'- 6" 3'-2" × 4'-10" 30" × 26" 2 2'-10" × 4'-10" 3'-2" × 5'- 2" 34" × 16" 2 3'- 2" × 3'- 2" 3'-6" × 3'- 6" 34" × 20" 2 3'- 2" × 3'-10" 3'-6" × 4'- 2" 34" × 26" 2 3'- 2" × 4'-10" 3'-6" × 5'- 2" 40" × 26" 2 3'- 8" × 4'-10" 4'-0" × 5'- 2" 42" × 26" 2 3'-10" × 4'-10" 4'-2" × 5'- 2" 52" × 26" 2 4'- 8" × 4'-10" 5'-0" × 5'- 2"
_Basement Sash, 1-3/8" Thick_
20" × 14" 2 2'- 0" × 1'- 5" 2'-4" × 1'- 9" 30" × 14" 3 2'-10" × 1'- 5" 3'-2" × 1'- 9" 42" × 14" 3 3'-10" × 1'- 5" 4'-2" × 1'- 9"
_Casement Sash, 1-3/8" or 1-3/4" Thick_
20" × 24" 4 2'- 0" × 2'- 5" 2'-4" × 2'- 9"[B] 20" × 36" 6 2'- 0" × 3'- 5" 2'-4" × 3'- 9"[B] 20" × 42" 6 2'- 0" × 3'-11" 2'-4" × 4'- 3"[B] 20" × 48" 8 2'- 0" × 4'- 5" 2'-4" × 4'- 9"[B] 20" × 56" 8 2'- 0" × 5'- 1" 2'-4" × 5'- 5"[B]
[Footnote A: If divided lights are wanted, a special order will be necessary, the total glass size remaining the same.]
[Footnote B: These heights are for outswinging casements; for inswinging casements, add 3/8" to the height of the dimensions given.]
Stock Door Sizes[C]
_Exterior Doors 1-3/8" or 1-3/4" Thick_
2'-8" × 6'-8" 2'-8" × 7'-0" 3'-0" × 6'-8" 3'-0" × 7'-0"
[Footnote C: Openings will be 4" wider and 2-3/4" higher than dimensions given.]
[Sidenote: Stock Sizes]
Brick linear dimensions should, wherever possible, be calculated so as to reduce cutting of brick to a minimum, especially where openings, bays, chimneys, and the like are concerned. Our plans are drawn with this in view; and to facilitate readily obtaining sash and exterior door sizes, we would suggest that contractors, so far as possible, use stock dimensions taken from the accompanying tables which cover the vast majority of requirements. For each mullion between grouped, double-hung windows allow 6 inches, and between casement windows 2 inches. The stock window frames, which are essentially the same as those used in frame construction, require no more labor to set and brace than in case of frame walls. All that is necessary is to box them in to make a housing for the sash weights. After the brickwork is laid around the frame, a staff bead or brick mold is nailed to its outside face, fitting snugly up to the brickwork, adding if so desired a scribing bead.
Should local stock frames vary slightly from the dimensions given, or if a scribing bead is used in addition to the regular staff mold, the brickwork can easily be laid so as to take up the difference. In case the masonry opening is finished before the frames arrive on the job, great care should be taken to have them built the exact size of the frame ordered, always taking into consideration the 1 inch to 6 inches slope of the sill, and the scribing bead if used.
Opening Supports
[Sidenote: Lintels and Arches]
[Sidenote: Relieving Arches]
The brickwork over all openings may be supported, either by a steel or wood lintel, or by a brick arch. Either the full thickness of the wall or the face brick only may be carried on a steel lintel or an arch. Lintels are rarely used in combination with semi-circular arches. When a steel lintel or an arch supports the face brick, the backing usually rests on a wooden lintel, set higher than the arch or else concealed by the frame. There should be a brick relieving arch above wooden lintels, spanning more than 3 feet, bearing on the wall beyond the ends of the lintel, so that the brickwork will not be weakened should the lintel be destroyed by fire (Fig. 28). The space between arch and lintel is filled with brick after the arch is built. Seasoned brickwork will support itself over the smaller spans.
[Sidenote: Steel Lintels]
For a steel lintel over a small opening, an angle is sufficient. If the interior wall surface is also to be of face brick, the lintel is made by placing two angles back to back, as the usual wood lintel in such a place would be unsightly. For openings up to 4 feet wide, a 4" × 3" or a 3" × 3" angle is sufficient; wider openings up to 5 feet would require a 3" × 5" angle. Over larger openings heavier sections of steel have to be used. Both steel and wood lintels are usually made 8 inches longer than the width of the opening.
[Sidenote: Brick Arches]
The brick arches generally employed in small buildings are flat, segmental, or full semi-circular (Figs. 25-29). The segmental and semi-circular arches are usually best built of rowlock courses, their number depending upon the width of the opening. Flat brick arches over two feet wide should be supported by steel, the brick being usually set soldier fashion. As these brick are slightly inclined from the vertical, their end edges should be clipped to make the joints on the face of the arch come in a horizontal line, as in Fig. 26. In Fig. 25, the appearance of the arch face is not so workmanlike and neat because the brick have not been clipped along the line of the middle joints. For either type of arch, the brickwork both sides of the opening must be beveled in the form of skewbacks, to serve as beds for receiving the thrust of the arch as shown in the figures. If these arches are properly handled both as to design and execution, they add greatly to the appearance of the entire wall surface.
Various Methods of Furring
[Sidenote: Wood]
[Sidenote: Hollow Tile]
[Sidenote: Metal]