Roofs for Farm-Buildings. 145 



rodf?. i in. T-sti'utts, 5 in. area. | in. 7"-principals, 62 in. area. 



Purlins, 8 x Sin. Ixafters, wall-plates, tiling and lathing, as No. 8. 



The cost of which is mi. 5s. lid.* 



Showing an addition of nearl}' 11. per square iu cost of iron over wood in 

 framing roof. 



No. 10, for Slating. — A roofformedofsix wood principals of the following scant- 

 ling: — Tie-beams, 8 x 4 in. Principals, 4 x 4 in. Braces, 3^ x 2 

 in. 2 X 5 in. wrought-iron straps and bolts at feet of 2:>rincipals. 

 Wrought-iron king-rod, 1 in. diameter, and cast-iron king-head. 

 Four purlins and ridge, 7 x 2^ in. Wall-plates, 4? x 3 in. 1 in. 

 rough close boarding, and best countess slating, 2^ in. lap, each, 

 slate fixed with two zinc nails. Slate ridges. 



The cost of which is &QI. lis. M.* 



This shows about ISi squares of slating, because there is an allowance for 



cut slates and wide caves. 



This is without doubt the best roof in every respect. It is easy of con- 

 struction, very durable, easily repaired, presents the best appearance externally 

 and internally, and, being boarded under the .slating, effectually protects the 

 interior from extreme alterations of temperature. 



No. 11, the same with iron introduced. — The roof formed of eight iron ]irincipals 

 of the following scantlings : — Tie and king rods, 1 in. in diameter. 

 i T-strutts, 4 iu. area. | T-pnncipals, 65 in. area, with purlins, 

 6 X 2^ in., wall-plates and ridges, boarding, slating and ridge, as 

 described in No. 10. 

 The cost of which is 68?. 9s. Qd* 



This, again, shows an increase of nearly 1/. per square, merely from the 

 substitution of iron for wooden principals. 



Detailed Calculations of the forego hi rj Estimates. 



No. 1. 



Wood Principals covered xvith Croggo'ii's Felt on Purlins. 



ft. in. £. s. d. 



38 8 cube. Fir in tie-beams, principals, king-posts) 



and braces f ■^'^' •' l** ^ 



No. 6 iron strains and wedges to kino-- 1 , ^ 



Dst .. .. .. .. .. f ^^ -^- 12 



cwt. qr. lb. 



pO: 



1 i 17 Wrought iron in straps, principals and) 



screw-bolts.. .."..'..-.. .. f ^'-^■^^'- " !» 



Fixing iron- work .. 10 



ft. in. 9 17 



43 cube. Fir framed in purlins and ridge .. .. 2s. 10c7. G 1 10 



9 5 „ Fir framed in wall-])late 2s. Qd. 1 f) 11 



50 run. Labour to rounded edge of ridge . . . . Id. 4 2 



1300 sup. Croggon's felt, nailed, tarred and sanded 14s. sq, 9 2 



£26 10 11 



* See for details of cost, pp. 147, 148. 

 VOL. I. — S. S. 



