142 Roofs for Farm-Buildiiigs. 



attained a sufficient height to burn the roof, the heated iron will 

 bend and twist in a way that will destroy the building quite as 

 quickly as in the other case. It is said that the London Fire 

 Brigade have a great aversion to iron construction, and feel much 

 less safe in such buildings when on fire. 



The expansion and contraction of iron principals in ordinary 

 changes of temperature, is sometimes regarded as an objection, 

 as tending to weaken the walls ; but, if sufficient play is allowed 

 for this in the construction, I do not think any inconvenient 

 results are to be apprehended. The question, then, whether iron 

 or wood should be used in the frame of a roof resolves itself into 

 one of cost. 



With a view of arriving at a reliable conclusion on this 

 point, I have supposed a building 50 feet long by 20 feet broad, 

 which may be taken to represent an average farm-building, to be 

 covered with a span roof, and I append descriptions of eleven 

 different roofs of this size, Avith estimates of their cost. The first 

 seven refer to the first part of the subject, the coverings of roofs ; 

 the last four to their frame, be it iron or wood. Nos. 10 and 11 

 are thoroughly 2(;e//-constructed roofs, covered with countess 

 slating laid on close boarding, without doubt the best roofing for 

 farm-buildings. 



It will be seen that the areas of the several roofs vary, accord- 

 ing to the slope, from 12^ to 14 squares, and that the substitution 

 of iron for timber principals entails an additional cost of about 1/. 

 per square in each case ; and this is a very moderate estimate of 

 the difference. For the prices given below, varying from 21. to 

 5/. per square, are calculated upon the full London rates of Avages 

 and full prices for timber, whilst the ironwork is priced at the 

 lowest estimate I have been able to obtain. Now, all the 

 carpenter's work will be subject to considerable reduction in 

 most country situations, where any ordinary village tradesman 

 can frame a wooden roof. Not so the ironwork. The ordinary 

 village smith is not equal to framing an iron roof, and as it would 

 generally be needful to bring experienced smiths from some large 

 town, it will be found that the more remote and thoroughly rural 

 the district, tlie greater will be the cost of such work ; and in 

 such situations a difference of even 2/. per square is not im- 

 probable. It is this last circumstance that occasions so marked 

 a contrast between farm-homesteads and other buildings, with 

 reference to iron construction. 



That the price of timber may eventually materially increase, 

 that rolled iron may hereafter be produced at a cheaper rate than 

 at present, and that ordinary country tradesmen may gradually 

 become more accustomed to iron work, are by no means im- 

 probable speculations ; but I am unable to resist the conclusion, 



