Brick

Estimating Brick

Brick sizes vary widely, and so do the costs. When estimating and pricing brick, keep in mind that larger brick may cost more per unit, but it takes far fewer units to complete a job, and the job will require less sand and mortar.

To estimate the number of brick per 100 sq. ft. of wall, refer to Brick Veneer Coverage, below. Or use the following formula (for standard 8x21/4x33/4 brick with a standard 3/8-in. mortar joint):

1 Square Foot of Wall = 6.8 Brick

Wall Height (ft.) x Wall Length (ft.) x 6.8 = Total Brick Needed

Expansion Joints

Expansion joints in brick masonry will prevent cracking due to thermal movement, moisture-absorption, and load effects. Accumulated movements are usually not large enough in residential construction to warrant expansion joints. However, long walls (over 75 ft.) can have problems.

Repointing Brick

Old brickwork should be repointed to protect it from further damage. Once mortar joints begin to fail, the deterioration can accelerate damage to the brick itself and increase the likelihood of leaks.

Raking Out Mortar

Old mortar should be removed (using a hammer, chisel, and a tuck-point grinder or a pneumatic chisel) to a minimum depth of two-and-a-half times the width of the joint. A depth of about 1 in. deep usually will ensure an adequate bond. Any loose or disintegrated mortar beyond this depth also should be removed. Clean joints carefully; damage to bricks will affect the appearance, and also can lead to accelerated weather damage (Removing Mortar, below).

Figure: Removing Mortar

Tuck-Pointing

• Dampen the brick and old mortar before filling the joint to control the rate of hardening, but avoid free water or excessive wetting. Too much water will delay the tooling or cause excessive shrinkage; too little water will reduce bond strength.
  
• Use only prehydrated lime mortar for tuck-pointing. A hard, Portland cement mortar may cause the brick to spall (Lime vs. Cement Mortar, below). To prehydrate, thoroughly mix dry mortar ingredients. Then add just enough water to produce a very stiff, unworkable mix (it should retain its shape only when pressed into a ball). Let stand for about two hours, and then add enough water to bring it to a good, workable consistency. This will be somewhat stiffer than conventional masonry mortars and will be much easier to work into joints.
• Where existing mortar has been removed to a depth greater than 1 in., compact the new mortar in several 1/4-in.-thick layers to reduce overall shrinkage. Allow each layer time to harden before applying the next layer.
• When the mortar is thumb-print hard, the joint should be tooled to match the existing joint (Tooling Joints, below). Proper timing of the tooling is important. If tooled when the mortar is too soft, the color will be lighter than expected, and hairline cracks may occur. If tooled too hard, there may be dark streaks called “tool burning,” and the mortar will not bond tightly to the brick.

Figure: Lime vs. Cement Mortar

Figure: Tooling Joints

Cleanup

If repointing work is done carefully, the only cleaning required after tooling will be a small amount of mortar brushed from the edge of the joint with a stiff bristle brush. This is done after the mortar has dried, but before it is fully hardened (one to two hours). Mortar that has hardened can usually be removed with a wooden paddle or, if necessary, a chisel.

Efflorescence, or “bloom,” may appear within the first few months after repointing, but it usually disappears through the normal weathering process. If natural processes do not remove the efflorescence, the safest way to remove it is by dry-brushing with stiff natural- or nylon-bristle brushes and water. Usually, muriatic acid is ineffective and it should be avoided. In fact, it can deposit salts, which can lead to additional efflorescence.