21 



it in against the pressure of concrete in the beam. This 

 also enables one to provide for a beveled edge on the 

 centering along the beam by beveling the edge of the 

 beam side. Another method of procedure is to form 

 the sheeting the full width and length of the floor 

 panel, letting the beam forms come up under the sheet- 

 ing. With heavier lumber any required bevel can be 

 taken care of on the sheeting. Then in wrecking there 

 will be sufficient "hang" to the sheeting, whether loose 

 strips or panel type, so that it will stay in place till 

 everything else is down and out of the way. 



It frequently happens that openings have to be pro- 

 vided for in floors or flat roofs for skylights, or ven- 

 tilator ducts or for other purposes. Unless these open- 

 ings are very large, it will not pay to cut a hole in 

 the floor centering. It is much more economical to 

 sheet over the whole floor and then build a light frame 

 as deep as tfie thickness of the slab and of the same 

 size as the opening. Tack this lightly in place on the 

 sheeting. It will serve to stop off the concrete and 

 leave the desired opening after which it may be easily 

 removed when the centering is wrecked. 



A few words about erecting. The column boxes are 

 first. Get them lined up and plumbed and then brace 

 temporarily but strongly. Do not put on the collars the 

 first thing, at least not more than are absolutely nec- 

 essary. It may be important to remove a side to get 

 at the steel later. The girder and beam bottoms go up 

 next, each supported on as few shores as possible for 

 the time being. Center them up at about the right 

 level and brace. Then put a camber or crown to each 

 one,' determined by experience, perhaps foin.. perhaps 

 5^-in., to allow for settling. The camber refers more 

 particularly to the center. Have the shores rest on 

 substantial wedges. By carefully driving these wedges 

 you can get your level quickly and accurately. In the 

 case of a first floor whose shores are supported on the 

 ground, provide short base planks for foundations for 



