The angled arrows marked “A” in figure 7-11 indicate the location of the cutting plane for the sections. To help you understand the importance of wall sections to the craftsmen who will do the actual building, look at the left wall section in figure 7-15 marked “masonry  construction.”  Starting  at  the  bottom,  you learn that the footing will be concrete, 1 foot 8 inches wide and 10 inches high. The vertical distance to the bottom  of  the  footing  below  FIN  GRADE  (finished grade, or the level of the finished earth surface around the house) varies-meaning that it will depend on the soil-bearing  capacity  at  the  particular  site.  The foundation  wall  will  consist  of  12-inch  concrete masonry  units  (CMU)  centered  on  the  footing. Twelve-inch blocks will extend up to an unspecified distance below grade, where a 4-inch brick facing (dimension indicated in the mid-wall section) begins. Above the line of the bottom of the facing, it is obvious that 8-inch instead of 12-inch blocks will be used in the foundation  wall. The building wall above grade will consist of a 4-inch brick facing tier, backed by a backing tier of 4-inch cinder blocks. The floor joists consist of 2 by 8s placed 16 inches OC and will be anchored on 2 by 4 sills bolted on the top of  the  foundation  wall.  Every  third  joist  will  be additionally  secured  by  a  2  by  1/4  strap  anchor  embedded in  the  cinder  block  backing  tier  of  the  building  wall. Window A in the plan front elevation in figure 7-13 will have a finished opening 2 5/8 inches high. The bottom of the opening will be 2 feet 11 3/4 inches above the line of the finished floor. As shown in the wall section of figure 7-15, 13 masonry courses (layers of masonry units) above the finished floor line will equal a vertical distance of 2 feet 11 3/4 inches. Another 19 courses will amount to the prescribed vertical dimension of  the  finished  window  opening. Figure 7-15 also shows window framing details, including  the  placement  and  cross-sectional  character of the lintel. The building wall will be carried 10 1/4 inches, less the thickness of a 2 by 8 rafter plate, above the top of the finished window opening. The total vertical distance from the top of the finished floor to the top of the rafter will be 8 feet 2 1/4 inches. Ceiling joists and rafters will consist of 2 by 6s, and the roof covering  will  consist  of  composition  shingles  on wood  sheathing. Flooring will consist of a wood finished floor on a wood subfloor. Inside walls will be finished with plaster on lath (except on masonry, which would be with or without lath as directed). A minimum of 2 vertical feet of crawl space will extend below the bottoms of the floor joists. The middle wall section in figure 7-15 gives similar information  for  a  similar  building  constructed  with wood-frame walls and a double-hung window. The third  wall  section  in  the  figure  gives  you  similar information for a similar building constructed with a steel frame, a casement window, and a concrete floor finished  with  asphalt  tile. DETAILS Detail drawings are on a larger scale than general drawings, and they show features not appearing at all, or appearing on too small a scale, in general drawings. The wall sections in figure 7-15 are details as well as sections, since they are drawn on a considerably larger scale than the plans and elevations. Framing details at doors, windows, and cornices, which are the most common types of details, are nearly always shown in sections. Details are included whenever the information given in the plans, elevations, and wall sections is not sufficiently “detailed” to guide the craftsmen on the job. Figure 7-16 shows some typical door and window wood framing tails, and an eave detail for a very simple type of  cornice.  Figure  7-17  shows  architectural  symbols  for doors  and  windows. SPECIFICATIONS The  construction  drawings  contain  as  much information about a structure as can be presented graphically. A lot of information can be presented this way, but there is more information that the construction craftsman must have that is not adaptable to the graphic form of presentation. Information of this kind includes quality  criteria  for  materials  (for  example,  maximum amounts of aggregate per sack of cement), specified standards  of  workmanship,  prescribed  construction methods, and so on. When there is a discrepancy between the drawings and the specifications, always use the  specifications  as  authority. This kind of information is presented in a list of written  specifications,  familiarly  known  as  the  specs.  A list of specifications usually begins with a section on general conditions.    This section starts with a general description   of   the   building,   including   type   of foundation, types of windows, character of framing, utilities to be installed, and so on. A list of definitions of terms used in the specs comes next, followed by certain  routine  declarations  of  responsibility  and  certain conditions to be maintained on the job, Figure 7-18 shows a flow chart for selection and documentation of concrete   proportions. 7-16