BUILDING CONSTRUCTION 317 



board or wainscoting. The ground makes it possible to 

 finish the wall to a perfect surface and leave it so that cas- 

 ings, baseboards, and moldings may be nailed down tightly 

 to the plaster. Grounds are usually ^ or y& inch thick. 

 They are 1 inch wide for window and door work, and 4 inches 

 wide for base and wainscoting. Metal lath may be used 

 instead of the wood lath. Metal corner beads are a recent 

 improvement. They make it possible to finish corners so 

 that the cracking of the internal corner is largely eliminated 

 and the damaging of the reentrant corner avoided by a. 

 metal edge. 



Plaster work is known as two-coat and three-coat work. 

 The first is the scratch coat. It is intended just to cover the 

 lath. The second is the brown coat. It is leveled and 

 floated to a true surface. The third or finish coat may be 

 either a sand float or a putty coat ; the sand float is a rough 

 surface, owing to the admixture of sand with the plaster; 

 the putty coat is perfectly smooth and white, with no sand 

 in it. In two-coat work the scratch and brown coat are run 

 practically together. 



Quantities for Plaster Work for 100 Square Yards 



Scratch coat: 350 lb. water-slaked lime and % cu. yd. of screened sand 

 Sand float finish: 300 lb. water-slaked lime and x /i cu. yd. screened 



sand 

 Using Keene's cement, first coat: 1 part cement, 1 part lime, 3 parts 



sand 

 Second coat: 1 part cement, 1 part lime, and 4 parts sand 

 Finish coat: 6 parts cement and 1 part lime 



Patent plaster and Keene's cement are put up in sacks. 

 They are both sold by the ton. 



Painting. We shall consider under this head both exterior 

 and interior painting and other finishes for wood and floors. 



Exterior painting. All outside surfaces should be primed 

 and painted two coats. The surface should be thoroughly 

 dry and clean. Knots are full of pitch which will discolor 

 the paint if precaution is not taken. This precaution means 



