



ROOF. 



let 



to the dfavMoHfoaato height it rr ( tiros on one : de of the building. 

 The best Bgure for a simple roof U that formed of two inclined plane*, 

 rWtur from the two opposite walls that approach nearest to each other 

 tod meeting over the centra of the edific*, so as to form a ridge. By 

 this form, supposing the same slope to be maintained, one-half of the 

 height of the single inclined plane is avoided; and the length of the 

 Umbers being -tiini"(* t ^~ l one-half, their scantling may be considerably 

 rrduc- n-preatata a pUn with side and end views of such a 



root which u called a common or gatl+*>ll roof. Frequently four 

 \ plane* are wed, disposed at shown in fy. 2, representing a 



Hg. 1. 



End. 



kipped roof, which takes its name from the hips, or inclined ridges 

 formed by the meeting of the sides and ends. \Vhere a hipped roof 

 covers a perfectly square building, tho faces all meet in a point, and 

 it when, as in the diagram, the plan of the roof is 

 rising from the nearest opposite walls meet in a 

 ued faces are nut continued upwards till 



form a pyramid 

 .Wong, the plat 

 ridge, gornetu 



they meet, but tho roof is completed by a horizontal plane. Such a 

 roof is called a Irnnralnl, terruet, or fat roof, and may have two, three, 

 r inclined faces. Pi.: 3 represents a truncated roof hipped at 



: . . . 



r.,,,i. 



i no end, and terminating at the other in a vertical wall, like tho gable- 

 t-nded roof. 



This arrangement is useful for diminishing the height of a roof, the 

 level platform being covered with lead to compensate for the want of 

 dope. It should be observed, however, that even this pirt in not per- 

 fectly level, the centre being slightly elevated to throw off water. A 

 uiiu'Ur saving, of height is frequently obtained by means of a roof in 

 which each sloping face consists of two planes of different degrees of 

 inclination. This form, which U denominated a curb ronf (or, from its 

 inventor, a Maiuardt roof), is very common in London, because it 

 afford* more space for the formation of bedrooms in the roof than the 

 rimpler forms. A curbed roof may be hipped or not, according to 

 circumstances. Pig. 4 represents it hipped at one end only, as the last 



similar to a valley, but in a horizontal instead of an inclined position, 

 the term gutter is applied instead of valley. 



A further distinction, which it may bo well to mention before 

 entering upon the details of construction, is that between roofs with 

 dripping eaves, and those in which the water is collected in gutters. 

 In the former case the roof projects several inches, or even feet, beyond 

 the walls, and the water running from the roof either drops at once on 

 the ground, or is collected in troughs fixed under tin- margin of the 

 eaves, and conducted by them to descending pipes. This arrangement 

 has a clumpy appr irance, and is perhaps HDIHTI- llicient 



projection is given to the eaves, though it is essential to the dryness of 

 the walls when they are of the diminutive size often adopted by 

 modern builders. In gutter roofs the timbers do not extend to the 

 outside of the walls, which are carried up as parapets, of a reduced 

 thickness, to such a height as to conceal tho roof either wholly or 

 partially. The gutters, which are troughs of wood covered with lead 

 or other metal, are laid at the bottom of the slopes, just within the 

 parapets, and have a gentle inclination (usually about an inch in ten 

 feet), to cause water to run freely towards the ]>i)"s. In ext 

 roofs it i well to use two or more falls instead of one, that the, 

 elevated end of the gtitter may cover as little of the roof as need be. 

 Similar troughs are often used in the valleys. Gutters are gei 

 made wide enough for n man to walk along them, and should be suftt- 

 ciently capacious to avoid all risk of overflowing during a sudden 

 heavy fall of rain. 



The degree of slope given to the inclined faces of a n> <t 

 according to the covering material employed, as well as to the climate. 

 The ancient Grecian temples had very low, or pediment roofs, varying 

 from about 12 to about 16, the height being from one-ninth t 

 seventh of the span. In Roman buildings the inclination is somewhat, 

 greater, being usually 23 or 24, or from one-fifth to two-ninths of 

 the span. The general introduction of the pointed style of architec- 

 ture led to the use of very high-pitched roofs, a very common 

 proportion being that in which the length of the rafters is the same as 

 the span, so that they formed an eqtiilateral triangle. In comparatively 

 modern domestic architecture in this country, it has been considered 

 desirable for the length of the rafters to be three-fourths that of the 

 span, and an angle of 45 is still considered by some to be the best 

 pitch when plain tiles are used. As builders can, in the present day, 

 obtain excellent covering materials, the pitch may be made of any 

 required degree, down to the low Grecian pediment, and it therefore 

 depends on the style of architecture and the taste of the builder ; the 

 most common height being from one-fourth to one-third of the span. 

 High roofs discharge rain the most rapidly, and do not retain snow so 

 much as those of low pitch ; but where they have gutters they are 

 liable to become choked by snow sliding into them, and to overflow 

 from water running into them faster than the pipes can convey it 

 away. Steep roofs may be covered with small slates, and. are ten 

 likely to be stripped by violent winds. Low roofs, in consequence of 

 their superior lightness, are less expensive, the timbers not only being 

 shorter, but of proportionately smaller scantling, and they press less 

 injuriously on the walls. The following table, extracted from Tred- 

 gold'g ' Elementary Principles of Carpentry,' shows the proper angle 

 for roofs covered with the materials specified in the first column, 

 the last column indicating the comparative weight of each kind of 

 covering : 



Height of roof 

 Inclination to in parts of 

 the horizon. 



honing, like the previous diagrams, the plan, and side and end 

 elevations. 



:i are tho prim:i|ial forms of roof used in covering simple rectan- 



building*, but they require many modifications to suit irregu- 

 Uritie* of *hai>e or combinations of rectangular forms. Thus, in fi<j. 5 



whieli represent the junction of different roofs or portions of 





r.ich other, tho lines a n u in 



;' two planes in such a manlier a* to form hollows the 

 i'f hips. Whon.two faces of a roof join so a* to form an angle 



Covering. 

 Copper or lead . 



Mali's, large 

 ordinary 



Slone date . 



rinin tiles 



Pun-tiles 



Thatcu of straw, 

 li> ath . 



reeds, or 



3' 50 



|l 



26' 3J' 

 29' 41' 

 29' 41' 

 2T 



45 1 



the span. 



A 



Weight upon a 



square of 



roofing.* 



[ eopper 100 



[ load . 700 



1120 



900 to 50(1 

 2380 

 1780 



In describing the timber-work of an ordinary roof, each of the 

 planes of which it is eoinpi.sed may be considered to be boundi 

 frame, the parts of which have the general name of bordering pieces. 

 Tin i-.- whieh j"-in th wall are the wall-)ilntri ; that at the meeting of 

 s, parallel to tin- wall-plates, is the ridge-piece ; and the ii" 

 :.-udiiip; from the wall-plates to the ridge pirn' are raflert, tho. e 

 whieh foi in tli"' salient angles in hipped roofs being distingui-l' 

 hili-riiftm. The support 1160688817 for the external covi-ring is given 

 i ies of rafters or inclined bars, extending from the wnll-plate.- 

 to the ridge-piece, and placed parallel with each other at 

 distances. In a hipped roof, the rafters near the ends; being p 

 with thiMtthi i ly diminished in length . extending from 



the wall-plate to tho hip rafter instead of tli" - All MI .-h 



pieces, being shorter than the length between the wall-plate and the 



piece, are i-jiii 



It is not \: Ming, or ti Amiens!. 'iis nf 



rafu-rs, in any considerable degr>v. "i> neeoiint. of their various lengths; 

 ne.uly the same scantling being used in all buildings, and the re<iuuvd 



* A < pi;irc of roofing contuins H'0 itquurc feet. 



