WOODEN FLOOES AND CEILINGS 



69 



door has to be planed away to some extent in order that it may clear 

 the floor covering when the door is swung open. This leaves an unsightly 

 and objectionable gap between the door and its sill when the former is 

 closed. 



The joist nearest the outside door having been laid as explained, the 

 remaining joists are laid with their top edges level with it. This is done 

 with the aid of a long straightedge and a spirit-level. Any joist, 

 where too high, is lowered by checking out pieces from its under edge, 

 above wall-plates and sleepers. Joists, where too low, may be packed 

 up by thin slips of wood nailed to the top edge of sleeper or wall-plate. 

 The joists are nailed to the wall-plates and sleepers by nails driven at 

 an angle from the sides of the joists ; this is termed " stitch nailing." 



The flooring boards are commonly 6" by 1" in cross section, and are 

 grooved and tongued. If one of them be examined it will be seen that 

 neither groove nor tongue is in the middle of the thickness of the board ; 



Fig. 69. 



they are nearer one face than the other. The former face should be laid 

 downwards as in Fig. 69. This allows for the wear on the upper surface 

 of the floor. The flooring boards are nailed to each joist, the 2£" nails 

 used being driven near the joints as shown in the figure. As a rule wall- 

 plates, sleepers, and flooring joists are tarred. The under side of the 

 flooring boards should also be tarred. If white ants are feared the wall- 

 plates, sleepers, flooring joists, and flooring boards, before being tarred, 

 should be well soaked in a solution of corrosive sublimate (HgCl 2 ) in 

 water, in the proportion 6 oz. corrosive sublimate to 1 gallon water. If 

 a large enough bath, or tank, be not available for this purpose, the wood 

 may be painted two or three times with a solution of corrosive sublimate 

 in methylated spirits in the above proportions. Besides rendering the 

 wood repugnant to ants, this treatment also tends to prevent dry rot. 



Ventilation under Wooden Floors. — It is most important that good 

 ventilation should be provided under wooden floors, in order to prevent 

 dry rot. Ventilation is arranged for by building air-bricks consisting of 



