Johnson Level & Tool Mfg. RAS-1 User Manual

Page 34

Now, draw the bottom plumb line using your inch rise on

the common scale of the square, exactly as you did for

the common rafter (see Figures 18 and 19). If you wish to

conserve wood, adjust the bottom plumb line so that its

length is equal to the step rise. Next draw the bottom floor

line by measuring down the bottom plumb line the dis-

tance of the step rise minus the tread thickness. In our ex-

ample, with a 1" tread; 7.29" minus 1.00" giving you 6.29",

or 6 5/16". Use the square the same way as you did for the

bird’s mouth horizontal seat mark (See 7A & 7B and 19).

FIG. 19 Step Layout.