Page:EB1911 - Volume 23.djvu/737

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ROOFS
701


Roofing felt is an inexpensive fabric of animal or vege-Al, table fibre treated Felt ~ ' ' 5 "ir with asphalt to make it capable of resisting the <."" g weather. It is largely used ///' l Q as a roofing material for tem// / I | porary buildings. When ex/ ! 1 posed to the weather it should f // l l be treated with an application 2; B- l: of a compound of tar and / 'l; slaked lime well boiled and ljjqf; I "['121 ]S$. J/ I applied h0t, the surface being I; ' 7, sprinkled with sand before it /1 ' (g E becomes hard. Feltbisldalso /' ' ¥'~» . Q? } 2361 °§ 00§ e”'§§§ i'§§ du§ l0r'”§ ! i , heat under slating and other | roof-covering materials. In ¢ "°= i ' th'Sd°§ Se EE fs § °t1i§§ 'i§ iii; | san e s s pp 1. ' I | containing from 25 to 35 yds. / ~~ ', r - ' ' - C-I 30111. wide. The sheets should < ' "'~~., ~ A- -4- be laid with a lap of 2 in. at ~ , - the joints and secured to the " ' 5 ' | N boarding beneath by large-1 WT" { L headed clout-nails driven in IiF!1§ -lf' - - - - - 4/ “b§ %E%;';;1§ 'é'a5$¢.3 is Sugpraid 7'1" """"' /ft eit er ac or ga vanize . t /jg E 'i' |¢| is especially suited can f?'jZ;f/1 41;/. Err B for the roofs of out- mgaied 7 ' ', , . buildings and build-, mn ”' A 'ji 'ij iii' ings of a mor; or less B “' "' temporary c aracter. eing 1 to a large extent self-support-O DE3'-r'q““ HT C' ing, it requires a specially de-2; Q signed roof framework of light 5 1 OO '- construction. If, as is usually f' ', K . - the case, the sheets are lard W ' with the corrugations runninfg HTA- (Q with the slope of the 100, they can be fixed directly on I purlins spaced 5 ft. to IO ft. FIG. 9.-Queen-rod Roof Truss. apart according to the stiffness and length of the sheets. In crown the spaces between the ribs are left open for ventilation. The sanctuary dome differs in several respects from those of the nave. Unlike the latter, which seem to rest on the fiat roofing of the church, the dome of the sanctuary emerges gradually out of the substructure, the supporting walls on the north and south being kept down so as to give greater elegance to the eastern turrets. The apsidal termination of the choir in the east is covered in with a concrete vault surmounted by a timber roof, in striking contrast to the domes covering the other portions of the structure. Fig. 13 is a section through the nave showing how the domes are buttressed, fig. 14 is a section through the sanctuary dome, and IIPIE, DI¢<1(il2.¢¢II*'l Of 5 "FFT X li asf ili ' 'l '“""" I

so

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ex ' ep // f -1 .ai | 1-8. f H1 V5 9 / A yas; s i'&"@"° 'I *' "'°" ¢ l -L 1| " ” w- ngs. IS and 16 a section and part plan of the vaulting of the choir with /  », ., -its wood span roof above the con- Crete vault. '  » Covering Materials for Roqfs.-There .6 ." are a large number of different roof- (-l'-'QF covering materials in common use, of, " / which short descriptions, giving the ¢f" '@;:¢~, ' '¢* principal characteristics, may be useful. - ”, M/Q, The nature of the material employed T /' QW" as the outer covering afiects the details i ' gf, / @"'Q¢', of roof construction very considerably. l l i ' 'rr 6. A light covering such as felt or corru- I gated iron can be safely laid u pon a much OF 5Fl0E5° ighter timber framing than is necessary tor a heavy covering of tiles or slates. FIG. Io.-Roof at Cardiff Station.