SECTION II. BRICKLAYING METHODS
9-20. Good bricklaying procedures depend on good workmanship and efficiency. Efficiency means to do the work with the fewest possible motions. Each motion should have a purpose and accomplish a particular result. After learning the fundamentals, study your own work to eliminate unnecessary motions, thereby achieving maximum efficiency. Organize your work to ensure a continual supply of brick and mortar. Plan the scaffolding before the work begins, and build it so that it interferes as little as possible with other workers. Paragraphs 7-3 and 7-4 describe mason's tools and equipment, which are generally the same as, or similar to, those used in bricklaying.
BRICK MASONRY TERMS
9-21. You need to know the specific terms that describe the position of masonry units and mortar joints in a wall (see Figure 9-3). These terms include:
Figure 9-3. Masonry units and mortar joints
TYPES OF BONDS
9-22. The term bond as used in masonry has three different meanings: structural bond, mortar bond, or pattern bond. Metal ties are also used as bonds.
Structural bond. This means how the individual masonry units interlock or tie together into a single structural unit. You can achieve structural bonding of brick and tile walls in one of three ways:
Mortar bond. This is adhesion of the mortar joint to the masonry units or to the reinforcing steel.
Pattern Bond. This is pattern formed by the masonry units and mortar joints on the face of a wall. The pattern may result from the structural bond or may be purely decorative and unrelated to the structural bond. Figure 9-4 shows the six basic bond patterns in common use today: running bond, common or American bond, Flemish bond, English bond, stack bond, and English cross or Dutch bond.
-Running bond. This is the simplest of the six bonds, consisting of all stretchers. The bond has no headers, therefore metal ties usually form the structural bond. The running bond is used largely in cavity wall construction, brick veneer walls, and facing tile walls made with extra wide stretcher tile.
- Common or American bond. This is variation of the running bond having a course of full-length headers at regular intervals that provide the structural bond as well as patterns. Header courses usually appear at every fifth, sixth, or seventh course, depending on the structural bonding requirements or the common bond that will vary with a Flemish header course. In laying out any bond pattern, be sure to start the corners correctly. In a common bond, use a three-quarter closure at the corner of each header course.
- Flemish bond. Each course consists of alternating headers and stretchers. The headers in every other course center over and under the stretchers in the courses in between. The joints between stretchers in all stretcher courses align vertically. When headers are not required for structural bonding, use bricks called blind headers. Start the corners two different ways; in the Dutch corner, a three-quarter closure starts each course, and with the English corner, a 2-inch or quarter closure starts the course.
- English bond. This pattern consists of alternating courses of headers and stretchers. The headers center over and under the stretchers. The joints between stretchers in all stretcher courses do not align vertically. Use blind headers in courses that are not structural bonding courses.
- Stack bond. This is purely a pattern bond, with no overlapping units and all vertical joints aligning. You must use dimensional-accurate or prematched units to achieve good vertical joint alignment. You can vary the pattern with combinations and modifications of the basic patterns shown in Figure 9-4. This pattern usually bonds to the backing with rigid steel ties, or 8-inch-thick stretcher units when available. In large wall areas or for load-bearing construction, insert steel-pencil rods into the horizontal mortar joints as reinforcement.
- English cross or Dutch bond. A variation of the English bond, the English cross or Dutch bond differs only in that the joints between the stretchers in the stretcher courses align vertically. These joints center on the headers in the courses above and below.
Metal ties. When a wall bond has no header courses, use metal ties to bond the exterior wall brick to the backing courses. Figure 9-5 shows three typical metal ties.
Figure 9-4. Types of masonry bond
Figure 9-5. Metal ties
9-23. Install flashing at any spot where moisture is likely to enter a brick masonry structure. Flashing diverts the moisture back outside. Always install flashing under horizontal masonry surfaces such as sills and copings and at intersections between masonry walls and horizontal surfaces. This also includes roof and parapet or a roof and chimney, above openings such as doors and windows, and frequently at floor lines, depending on the type of construction. The flashing should extend through the exterior wall face and then turn downward against the wall face to form a drop. Provide weep holes at intervals of 18 to 24 inches to drain water that accumulates on the flashing to the outside. Weep holes are even more important when appearance requires the flashing to stop behind the wall face instead of extending through the wall. This type of concealed flashing with tooled mortar joints often retains water in the wall for long periods and, by concentrating the moisture at one spot it does more harm than good.
MAKING AND POINTING MORTAR JOINTS
9-24. Pointing is filling exposed joints with mortar immediately after laying a wall. You can also fill holes and correct defective mortar joints by pointing, using a pointing trowel.
9-25. There is no rule governing the thickness of a brick masonry mortar joint. Irregularly shaped bricks may require mortar joints up to 1/2 inch thick to compensate for the irregularities. However, mortar joints 1/4 inch thick are the strongest. Use this thickness whenever the bricks are regular enough in shape to permit it.
9-26. A slush joint is made simply by depositing the mortar on top of the head joints allowing it to run down between the bricks to form a joint. You cannot make solid joints this way. Even if you fill the space between the bricks completely, there is no way you can compact the mortar against the brick faces, and a poor bond will result.
PICKING UP AND SPREADING MORTAR
9-27. Figure 9-6 shows the correct way to hold a trowel firmly in the grip with your thumb resting on top of the handle, not encircling it. If you are right-handed, pick up mortar from the outside of the mortar-board pile with the left edge of your trowel (see Figure 9-7 below). You can pick up enough mortar to spread one to five bricks depending on the wall space and your skills. A pickup for one brick forms only a small pile along the left edge of the trowel, however, a pickup for five bricks is a full load for a large trowel as shown in view 2 of Figure 9-7.
Figure 9-6. Correct way to hold a trowel
Figure 9-7. Picking up and spreading mortar
9-28. If you are righthanded, spreading the mortar working from left to right along the wall. Holding the left edge of the trowel directly over the centerline of the previous course, tilt the trowel slightly and move it to the right (see view 3 Figure 9-7) dropping an equal amount of mortar on each brick until the course is completed or the trowel is empty. Return any leftover mortar to the trowel mortarboard.
MAKING BED AND HEAD JOINT
9-29. Do not spread the mortar for a bed joint too far ahead of laying (the length of 4 or 5 bricks is best). Mortar spread out too far ahead dries out before the bricks bedded in it and causes a poor bond as shown in Figure 9-8. The mortar must be soft and plastic so that the brick beds in it easily. Spread the mortar about 1 inch thick, and then make a shallow furrow in it (see Figure 9-9 below). A furrow that is too deep leaves a gap between the mortar and the bedded brick, which will reduce the wall's resistance to water penetration.
Figure 9-8. A poorly bonded brick
Figure 9-9. Making a bed joint in a stretcher course
9-30. Cut off any mortar projecting beyond the wall line with the edge of the trowel (see Figure 9-9 above). Use a smooth, even stroke. Retain enough mortar on the trowel to butter the left end of the first brick you will lay in the fresh mortar and throw the rest back on the mortar board.
9-31. Placing your thumb on one side of the brick and your fingers on the other, pick up the first brick to be laid (see Figure 9-10). Apply as much mortar as will stick to the end of the brick and then push it into place, squeezing out excess mortar at the head joint and at the sides as shown in Figure 9-11 below. Make sure that the mortar completely fills the head joint. After bedding the brick, cut off the excess mortar and use it to start the next end joint. Throw any surplus mortar on the back of the mortar board for retampering if necessary.
Figure 9-10. Proper way to hold a brick when buttering the end
Figure 9-11. Making a head joint in a stretcher course
INSERTING A BRICK IN A WALL
9-32. Figure 9-12 shows how to insert a brick in a space left in a wall. First, spread a thick bed of mortar (see Figure 9-12), and then shove the brick into it (see view 2 of Figure 9-12) until mortar squeezes out of the four joints (see view 3 of Figure 9-12). In doing so you are assured that the joints are full of mortar at every point.
Figure 9-12. Inserting a brick in a wall
MAKING CROSS JOINTS AND JOINTS CLOSURE
9-33. Spread the bed-joint mortar several brick widths in advance. Then spread mortar over the face of the header brick before placing it in the wall (see view 1 of Figure 9-13). Next shove the brick into place, squeezing out mortar at the top of the joint. Finally cut off the excess mortar as shown in view 2 of Figure 9-13.
Figure 9-13. Making a cross joint in a header course
9-34. Figure 9-14 shows how to lay a closure brick in a header course. Spread about 1 inch of mortar on the sides of the brick already in place (see view 1 of Figure 9-14), as well as on both sides of the closure brick (see view 2 of Figure 9-14). Then lay the closure brick carefully into position, without disturbing the brick already laid (see view 3 of Figure 9-14).
Figure 9-14. Making a closure joint in a header course
9-35. To make a closure joint in stretcher courses, first spread plenty of mortar on the ends of the brick already in place (see view 1 of Figure 9-15), as well as both ends of the closure brick (see view 2 of Figure 9-15). Then carefully lay the closure brick without disturbing the brick already in place (see view 3 of Figure 9-15). If you do disturb any adjacent bricks, you must remove and relay them. Otherwise, cracks will form between the brick and mortar, allowing moisture to penetrate the wall.
Figure 9-15. Making a closure joint in a stretcher course
9-36. Bricks will either be cut with a bolster or a brick set, using a brick hammer.
Using a bolster or brick set. When you must cut a brick to exact line, use a bolster (see Figure 9-16) or brick set. The straight side of the tool's cutting edge should face both the part of the brick to be saved, and the bricklayer. One mason's hammer blow should break the brick. For an extremely hard brick, first cut it roughly using the brick hammer head, but leave enough brick to cut accurately with the brick set.
Using a brick hammer. Use a brick hammer for normal cutting work, such as making the closure bricks and bats around wall openings or completing corners. Hold the brick firmly while cutting it. First cut a line around the brick using light blows. Hitting a sharp blow to one side of the cutting line should split the brick at the cutting line (see view 1 of Figure 9-17). Trim rough spots using the hammer blade as shown in view 2 of Figure 9-17.
Figure 9-16. Cutting brick with a bolster
Figure 9-17. Cutting a brick with a hammer
9-37. Purpose. The exterior surfaces of mortar joints are finished to make brick masonry more waterproof and give it a better appearance. If joints are simply cut flush with the brick and not finished, shallow cracks develop immediately between the brick and the mortar. Finishing or tooling the joint using the jointer shown in Figure 7-1 , Chapter 7, prevents such cracks. Always finish a mortar joint before the mortar hardens too much. Figure 9-18 shows several types of joint finishes, the more important of which are discussed below.
Concave joint. It is very weather tight. After removing the excess mortar with a trowel, make this joint using a jointer that is slightly larger than the joint. Use force against the tool to press the mortar tight against the brick on both sides of the mortar joint.
Flush joint. It is made by holding the trowel almost parallel to the face of the wall while drawing its point along the joint.
Weather joint. It sheds water from a wall surface more easily. To make it, simply push downward on the mortar with the top edge of the trowel.
Figure 9-18. Joint finishes
|David L. Heiserman, Editor||
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Revised: June 06, 2015