CITY BUILDINGS.
The requirements of city buildings, which are for the main part similar to the practices which we have already considered, are, nevertheless, in many essentials, distinct. In the first place, the circumstances of situation, soil and surroundings differ from sub urban or rural conditions. Instead of being able to establish our building to meet our individual tastes, we shall find that the side walk and yard levels are already established, and the level of the cellars or basements will be found to be restricted in some localities. The lines of our building will also be determined, in a great measure, by established lines and restrictions so that much more of prelimi nary work will be needed to make the most of the existing condi tions with which we find ourselves confronted.
Party Walls. Of great importance in laying out our build ing will be the existing agreements in regard to party walls. In most cases it will be found that there has been signed an agreement relating to the construction and use of party walls. The usual arrangement is that the party who first builds, shall build and pay for the wall, which is erected one-half on each side of the party line, and that the adjoining ovner shall have the right to use and acquire the half of wall which stands upon his side of the line, by paying to the party who has already built, the cost of one-half of the wall as already erected.
As buildings of different heights require walls of varying thick ness, it is usual to agree that no wall shall be primarily erected which extends more than six inches beyond the party line, so that if one owner desires to erect a building which will require a greater thick ness than one foot for the party wall, he must erect alI except six inches of the thickness of the wall upon his own land. While a party wall agreement will probably be a matter of record, which can be looked up in the proper place, much time may often be saved by looking for some information upon the spot.
Tf the land on either side of our lot be already occupied by a building, the conditions of the wall finish will ue likely to afford data upon which we can work. If the finished
brick or stonework covers apparently only one-half of the wall, leaving a surface of rough brick set back from the face or "ashlar line," Fig. 94, it will indicate that the wall is a party wall, as it is the usual practice for each owner to stop his front at the party line. If, on the other hand, we find the finished work covering the wall completely, Fig. 95, we may assume that the wall in question is not a party wall, but a wall built wholly upon the land of the adjoining owner. This evidence will be confirmed if, upon measuring the distance between the two lines in question, we find it to agree with the figures upon the sur veyor's plan with which we must be provided before laying out our plans. The matter of party wall rights is, however, too important to be settled to a sufficient degree, by mere observation, to permit of building operations, and so we shall need to apply to our client for a copy of any agreements or restric tions, and proceed to plan and con struct the new building s in accord ance with these.
Soil. If the nature of the soil upon which we are to build is not known, we must have borings made to show the composition of the soil at different levels. If two borings on opposite sides show about the same character, it will be sufficient evidence, but if these vary, then borings should be made all around. Rock, clay or gravel bottom will require only that our foundations shall he made wide enough to distribute the weight of the building, and its contents, over an area sufficient to sustain it. The bearing power of rock will vary from ten to thirty tons per square foot, dry day from four to six tons, gravel from eight to ten tons. If, however, the soil con sists of mud or filled land, such as will be found on the borders of lake or ocean, it will be necessary to drive piles, upon which the footings are supported.