72 FARM BUILDINGS IN SOUTH AFRICA 



The joists, being inclined to buckle under the load, must be 

 supported by 2" by 1£", or 3" by 1£" cross struts, as shown, at intervals 

 of not more than 3 feet. This strutting should be introduced in con- 

 tinuous lines, so as to gain the full stiffening effect. 



In the case of an upper floor, for instance for a dwelling-house, 

 which has not to bear loads due to stored materials, the 9" by 1£" 

 joists would still be 15 inches apart, but a distance up to 14 feet 

 may be spanned. Cross struts to prevent buckling should be inserted, 

 as in the case of the preceding floor. 



An upper floor which is ceiled below is referred to as a ceiled Jioor. 

 The ceiling usually consists of 6" by |" tongued and grooved boards, 

 nailed to the under side of the joists with small cut nails, 1£ inches 

 long, known as ceiling nails. The junction between ceiling boards 

 and walls is hidden by the cornice, which is nailed to the ceiling 

 boards, and also to wooden slips which are built into the wall for the 

 purpose while the wall is being raised. These wooden slips should 

 be inserted so that they project beyond the face of the brickwork by 

 an extent equal to the thickness of the plaster which is afterwards 

 to be applied. The same remarks apply to wooden slips built into 

 the wall to receive the skirting board which finishes the lower part 

 of the walls, just above the floor, and protects it from damage. Both 

 cornice and skirting board are nailed in position after the walls have 

 been plastered. 



The ceiling of a single -storey building, or of the upper apartments 

 of a two-storey building, is nailed to the under side of the tie-beams 

 of the roof trusses, and also to 4£" by 1|" ceiling joists, one of which 

 is inserted halfway between adjacent tie-beams. In Fig. 214a (roof 

 plan) the ceiling joists are marked CJ. They span from wall-plate 

 to wall-plate just as the roof trusses do. 



In conclusion, it should be mentioned that the ends of all joists 

 or beams, which are built into walls, should be tarred, and the wood 

 should be dry and well seasoned, so as to prevent disease such as dry 

 rot. Those surfaces of wall-plates which come in contact with the 

 masonry or brickwork should also be tarred. 



