BUILDING 



BUILDING 



Contracting. The men who supervise all 

 these workers are usually called contractors. 

 Sometimes a contractor agrees to erect a build- 

 ing for a stated amount of money, and if 

 through careful direction of his men and wise 

 buying of materials he is able to do it with 

 less expense than anticipated, the saving is his 

 profit. In other cases the owner of the building 

 pays all expenses and a commission to the con- 

 tractor. Frequently a contractor will in turn 

 engage others to do part of the work; thus 

 plumbing, wiring, plastering and similar tasks 

 are often handled by sub-contractors. To be 

 a successful contractor a man must possess a 

 thorough knowledge of building principles, be 

 able to estimate costs accurately and have the 

 ability to govern others and to direct their 

 operations so that good work will be done 

 without waste of time. Many contractors have 

 risen from the ranks of laborers. 



The Substructure. The two parts of a build- 

 ing, the substructure and the superstructure, 

 might theoretically be termed the below- 

 ground and the above-ground sections. But the 

 substructure includes the basement walls, which 

 in actual practice extend sometimes many feet 

 above the ground level. 



Footings. The narrow end of a shingle can 

 be pushed into the earth and the edge of a 

 board can be driven in, but the flat side of a 

 plank will support a very large weight without 

 sinking. If the foundations of a heavy build- 

 ing are set directly on the soil they will pene- 

 trate it like the shingle, but if they are built 

 on footings which, like the plank, are sus- 

 tained by a greater area of ground they can 

 be made nearly as solid as though on rock. 

 Footings may be of concrete, reinforced-con- 

 crete, flat stone, stone and brick, concrete and 

 brick, steel or timber. In very soft ground 

 they are sometimes set on piles, as are the tall 

 buildings of many large cities. 



For any except a light frame structure the 

 builders are always very careful to determine 

 the proper size of footings according to the 

 character of the soil and the weight of the 

 building. An illustration of what will happen 

 if the load is not evenly distributed to the foot- 

 ings is given in the illustration. Most large 

 buildings have isolated footings, with the size 

 of each one proportioned according to the 

 average load it will be called upon to bear. 

 The reason for making the average load the 

 basis of the plans will be clear if one will 

 suppose the case of a store building in the back 

 of which are kept the tons of stock, but the 



front of which is lightly loaded except when 

 crowds fill it on special sale days. If the foot- 

 ings are proportioned according to the greatest 

 load at any one time, those in front will be 

 stronger and the average load will cause those 

 at the back to settle more rapidly. On the 

 other hand, each footing must be large enough 



EXAMPLES OF FOOTINGS 



1. A continuous footing under an opening will 

 cause cracks, because, as shown by the arrows, 

 the downward pressure is all at the sides, and 

 there is in effect an upward thrust at the center, 

 which will "break the back" of the arch. 



2. Isolated footings, formed by omitting that 

 part of the footing beneath the opening, allow 

 uniform settlement, because all upward force is 

 directly under the downward pressure. 



to support its share of the greatest possible 

 load, which includes (1) the dead load, or weight 

 of the building itself; (2) the live load, or 

 weight of the people and objects which may 

 at any one time be in the building; (3) the 

 snow load, wind load and other emergency 

 strains. 



Footings must always be below the point 

 to which frost penetrates the ground, or they 

 will move to and fro and cause cracks in the 

 walls above. 



Foundations. Besides supporting the super- 

 structure, foundation walls must withstand the 

 inward thrust of the earth and, if there is a 

 cellar, keep out dampness. Stone or concrete 

 foundations are built at least eight inches 

 thicker than the wall next above them. Stone 

 is to some extent sponge-like, brick is more 

 so, and concrete walls admit water readily 

 unless covered with tar, asphalt or other water- 

 proofing substance. 



The Superstructure. The details of this part 

 of a building vary widely, according to the 

 materials of which its frame is composed. How 

 a wooden structure is put together is told in 

 the article CARPENTRY. 



Brick buildings are of two sorts, those which 

 have brick walls from twelve to forty inches 

 thick, and those with wooden walls and a brick 

 veneer only four inches thick. Both types are 

 often constructed with air spaces in the walls 



