Span.

Tie beam, T.

Queen Post, QP.

Princesses, PP.

Principal

Rafters,

PR.

Straining

Beam,

SB.

King Post, KP.

Struts, S.

Purlins, P.

Common

Rafters,

CR.

65 ft.

15byl0½

8 by 7

5by3

8 by 7½

10½ by 8

5by3

5 by 3½

8¼by5

4 by 2

70 "

15 " 11¾

9 "6½

5 " 3½

9 " 7

10½ " 9

5 " 3½

5 " 4

8½"5

4¼ " 2

75 "

15 " 13¾

9 "7½

5 " 4

9 " 8

11¼" 9

5 " 4

5 " 4½

8¾"5

4¼ " 2

80 "

16"13

9 " 9

6 " 4

10½ " 9

12 " 9

6 " 4

6 " 3½

8¾ " 5¼

4½ " 2

85 "

16 " 13½

9½ " 9

6 "4½

12 " 9

12¾ " 9

6 " 4½

6 " 4

9 "5¼

4¾" 2

90 "

16 " 14

10 "9¾

6 " 4½

13½"10

13 "10

6 " 4½

6 " 4

9 " 5i

5 " 2

N.B. - In these Tables the pitch of the roof is supposed to be about 27°; the trusses 10 feet apart. The covering slates and the timber to be good Memel or Riga fir. Inferior timber will require to be of larger dimensions. The scantlings for the tie beams may be considerably reduced when they do not carry ceiling joists. See Seddon's Tables, p. 52.