26 THE CONSTRUCTION OF THE FORCING-HOUSE. 
In Fig. to the rafters are in place, and on the further 
half the sash-bars have been put in between them, being 
toe-nailed at the upper end to headers cut in between 
the rafters. The space above these headers is to be cov- 
ered by the ventilator sash. 
It is very doubtful, however, if it is ever necessary to use 
zo. Putting up a rafter-and-sash-bar house. 
rafters in the construction of a forcing-house. The entire 
roof should be built wholly of sash-bars, which run from the 
sill or the plate to the peak, as shown in Figs. 12 and 13 
(pages 28 and 29). This construction admits the greatest 
amount of light to the house, and is also less expensive. 
If purlines of steam pipe are freely used upon which to rest 
