Problems in Estimating Quantities
Brick Problem
To find the number of standard size brick, face and common, laid in a sixth course Common Bond with a 3/8-inch joint, for an 8-inch gable wall, 25 feet wide and 18 feet high from grade to eaves and thence to ridgepole 12 feet. The 12-inch basement wall is 71/2 feet high, 4% feet being below grade. There are 4 windows each requiring an opening of 3’-6” × 5’-2” and 1 window requiring an opening of 2’-6” × 4’-2”. See window sizes page 22. The basement windows being less than 10 square feet are disregarded.
Face Brick
| First find the area in sq. ft. for face brick: | |
| Rectangle of wall 18’ × 25’ = | 450 sq. ft. |
| Gable triangle 12’ × 25’ = 300 - 2 = | 150 sq. ft. |
| Total area | 600 sq. ft. |
| Deduct the 5 window openings, thus: | |
| 4 × 3’-6” × 5’-2” = 721/3 sq. ft. | |
| 1 × 2’-6” × 4’-2” = 105/12 sq. ft. | |
| Window openings to be deducted | 83 sq. ft. |
| Total area to be covered with face brick | 517 sq. ft. |
| By Table 1, it takes 6.5 standard size face brick per sq. ft. for Running | |
| Bond with a 3/8” joint. | |
| Hence, 517 × 6.5 = | 3,360 |
| Add 162/3% as per Table 2 | 560 |
| Number of face brick required | 3,920 |
| Total of face brick to be ordered | 4,000 |
Common Brick
| The common brick backing takes the same number as face brick, except that we deduct the 162/3% added to the face brick quantity as per Table 2. Hence, the number of common brick for backing is 3,360 - 560 = | 2,800 |
| As the wall from grade to first floor is three brick thick, the same as the foundation wall, it requires two tiers of common brick and, therefore, an additional tier must be figured in. Hence, 25’ × 3’ or 75 sq. ft. at 6.5 per sq. ft. = | 488 |
| The 4’-6” of foundation wall, being three brick thick, gives us 25’ × 4’-6” × 3 or 388 sq. ft. to figure on. Hence, common brick for foundation is 388 × 6.5 = | 2,197 |
| Total common brick required | 5,485 |
| Total common brick to be ordered | 5,500 |
Hollow Tile Problem
By referring to pages 25 and 26, it will be seen that four courses of brick with a 3/8-inch joint equal in height two 5” × 12” tile, so that, in our present example, if we wish to use the 3/8-inch joint, we shall have to introduce our bonding course of brick every fifth instead of every sixth course. This would also naturally involve a slight change in the number of face brick required. That is, instead of adding 162/3% or we should have to add 20% or 1/5 to the number required for Running Bond, in order to get the right number for fifth course Common Bond and, in consequence, we subtract 20% or one fifth from the backing tile wanted. With these changes understood, our problem for a hollow tile backing for the gable wall will work out as follows:
If the hollow tile backing is started at grade, the tile and face brick area will be the same. But as, in the present case, we start the tile backing from the first floor, we subtract the area of the wall from grade to first floor or 25’ × 3’ = 75’, and get 517 - 75 or 442 sq. ft. to be backed with tile.
The closures for horizontal tile are figured separately. A full and a half closure are respectively 12 and 6 inches in length and amount to about one foot in height, and hence cover an area of 3/4 sq. ft. on each side or 11/2 sq. ft. on both sides of the opening. As the height of our five window openings is approximately 25 feet, we have 25 × 11/2 = 371/2 sq. ft. to be deducted from area of regular tile surface, giving 442 - 371/2 or 4041/2 sq. ft.
| As per coefficient table, page 106, we have 404.5 × 2.15 = | 870 |
| Deduct 1/5 of tile for brick bond | 174 |
| 696 | |
| Add 3% for wastage or | 21 |
| Total number of tile to be ordered | 717 |
| Requiring 4 closures, 2 full and 2 half, for each foot of height (both sides), we need 25 × 4 or 100 closures | |
| Add 3% for wastage or 3 | |
| Total number of closures needed | 103 |
| Order 52 of each size. | |
| Brick-size tile, 12 to every 16 sq. ft. >needed. Hence, 442 ÷ 16 gives about 28, and 12 × 28 = | 336 |
| Add 3% for wastage or | 10 |
| Total brick-size tile to be ordered | 346 |
Estimating Labor Required
Placing Brick and Tile
The usual method of estimating the labor bill for brickwork or tile is to reduce it to the amount per thousand brick or tile placed, which not only covers the bricklayers’ time, but the mortar, the necessary labor for mixing it, and the labor tending the bricklayers. This, of course, varies in different localities and with the different kinds of brick or tile, mortar, and joints. The contractor is urged to keep an accurate record of the number of brick or tile laid per day, the amount of mortar of various kinds used, and the number of bricklayers for which one laborer is necessary, so that he may determine for himself, from the total, the unit costs per thousand for placing brick or tile according to different specifications.
It must be carefully noted that such items as arches, piers, panels, special bond patterns, etc., require additional time for execution, depending upon their nature. The contractor will have to be guided by his own experiences in making allowances for the additional labor necessary for this work.
Building a Fireplace
It is difficult to estimate the labor required for building a fireplace, due to the variety of designs and the necessary amount of cutting and fitting required. Therefore many masons estimate this work at so much per fireplace or at a unit price per thousand brick. It may be said that a bricklayer should lay the face of a fireplace 5 to 6 feet wide and 4 to 5 feet high in ten hours, and the fire brick lining in from 4 to 6 hours. It will take about 4 hours’ time to lay the entire hearth. One-half hour of laborer’s time should be allowed for every hour of bricklayers’ time.
Cleaning Brickwork
The cost of cleaning and pointing face brickwork will vary with the kind of brick to be cleaned, as it is easier to clean brick with a smooth surface than with a rough texture. An experienced man should clean 95 to 100 smooth brick or 75 to 80 rough brick per hour.
Waterproofing Foundation Walls
For one-half inch plaster coating, composed of one part Portland cement to two parts sand, 2 bags Portland cement and 4 cubic feet of sand will be required to cover one square, that is, 100 sq. ft. of wall surface, and it will require one-half hour of laborer’s time for mixing. An experienced workman and helper should cover from 40 to 45 sq. ft. of surface per hour.
For a coating either of hot asphalt or of pitch, to be well applied with a heavy mop, approximately 200 pounds of material and a half day for two men will be required to cover 10 squares of wall surface. About one gallon of creosote sizing would be required per square, with only one-half to a quarter as much labor as for the waterproofing.
Handling of Materials
The storage space for all materials should be convenient to the building, and where the team can reach it so that rehandling may be avoided.
Face Brick
When face brick are delivered on the job, they should be immediately compared with the sample, previously selected, for color, size, and quality, to prevent any misunderstanding later when they are laid in the wall. If shipped by freight, they should be examined before being unloaded from the car. Face brick should be stacked in neat piles, laid either on edge, face up and protected with straw, or on their sides in such a way as to protect the faces. Laborers, in carrying face brick to the mason, should place them face up for the convenience of handling.
Common Brick and Tile
Except on large jobs, common brick are not usually stacked. They are dumped in a pile which makes it easier to wet them down thoroughly as explained later. Hollow tile should be stacked in neat piles to prevent undue breakage, each size and shape being piled separately.
Lime and Cement
Lump lime should always be stored in a covered box to keep it dry. This box should have a hinged opening on one side, at the bottom, from which the lime may be conveniently removed. Lump lime should be slaked at least a week before used to allow for thorough hydration and cooling. Hydrated lime and cement should be carefully protected from the weather by stacking the sacks on planks laid on the ground and by a covering of planks and tarpaulin.
Sand
The sand pile should be located as near the mortar box as possible for convenience in handling. In case the sand needs screening, an the sand pile should be located at such a distance from the mortar box that when the sand is thrown through the sieve, it will form a pile adjacent to the mortar box.
Wetting Common Brick
All brick, especially the softer grades of common brick, should be thoroughly wetted just before being placed in the wall, but not made so wet as to cause sliding on the mortar. The object of this wetting is to prevent the bricks from absorbing moisture from the mortar which must be allowed to dry slowly so as to obtain a good bond. If they are laid dry, the bricks will quickly take up a large amount of water from the mortar, preventing proper setting and adhesion. Water increases the weight of brick and consequently the labor of handling, so that some workmen are inclined to lay them dry. This should not be allowed except in freezing weather, when the conditions require quicker setting. Good mortar bond is essential to a good wall.
Work Done in Cold Weather
In latitudes where the winter temperature is prevailingly below freezing, all material for mortar, including water, should be heated. If this is done, the mortar will take its initial set before it freezes and no damage will result. In extremely cold weather, added precautions should be taken in case of footings by protecting them with manure. The following suggestions will be found useful for cold weather work.
When being laid the brick should be thoroughly dry; and if possible warmed. No bricks with ice on them should be laid in the wall, and cement or cement-lime mortar should be used to get quick setting. For heating sand and gravel, a corrugated sheet metal culvert, about 20 inches in diameter and about 10 feet long, may be used. A wood fire is built in the ends of the pipe over which the sand and gravel are piled. This easy and simple method will melt all frozen lumps in the material and dry out the resulting moisture.
Where city water pressure is available, the water may be heated in a coil attached to the main and large enough to have a fire built in the center, a very simple and efficient method which any plumber can easily install. Place a sheet-iron guard around the coil to conserve the heat. This equipment proves very satisfactory, as it warms the water as fast as it is drawn off through the hose. The entire installation may be found on the market at a comparatively small cost. Without such an arrangement the water may be heated in an ordinary iron kettle over a wood fire. Water should never be heated to the boiling point, as too high a temperature will injure the setting properties of the mortar.
A temperature of about 165 degrees, or the same as generally required for household uses, is best.
If the above conditions are met, brickwork may be continued practically throughout the entire winter, except only so far as the comfort of the workmen dictates. They will usually quit at about 20 degrees above zero, depending somewhat upon other weather conditions. If it is not too windy, they will work outside in a lower temperature than when it is very windy. A shelter, however, may very easily be constructed for the workmen by nailing a few 2” × 4” scantlings upright to the scaffolding with another 2” × 4” nailed along the top as a support for a tarpaulin. A salamander behind this shelter will make it quite comfortable for the workmen as well as help the mortar to set. As the use of wood in the salamander makes a too intense and irregular heat, besides giving off more or less smoke, coke is recommended. The amount of coke required on an ordinary job is so small as to be almost negligible.
The wall at any one point should not be carried very high in one day. It is better to work around the entire building a few feet at a time rather than to work on one side and carry the wall six or more feet high. Walls thus erected are apt to get out of plumb from the alternating effect of the night cold and the day sun.
As soon as the floor joists of any story are set in place and floored, the window and door openings of the floor below should be tightly closed, either by the permanent sash or by temporary boarding or building paper, so that salamanders may be placed inside to dry out the building thoroughly. Once a day the building should be aired.
If the above suggestions are followed, there is no reason why brickwork should not be continued through the average winter months. The extra work accomplished during the usually dull season is worth more to the contractor than the trouble he has taken or the additional cost of labor.