SLA

432

SLA

mode adopted to lay it on roofs, as no patent was everobtained for such a mode of slating. It was first broughtinto use by Mr. Wyatt, the architect. It allows of beinglaid on a rafter of much less elevation than any other kind ofslate, and is considerably lighter by reason of the laps beingless than is necessary for the common sort of slating. Thisslating was originally made from that description of slatesknown as Welsh rags. The slaters now frequently make itof imperials, which renders it still lighter, and somewhatneater in its appearance. Experiments have been insti-tuted on the Westmoreland slate by the Bishop of Llandaff,from which there appears very little difference in its naturalcomposition from that obtained from Wales .

Thirteen loads of the finest sort of Westmoreland slate willcover 42 square yards of roofing, and 18 loads of the coarsestwill cover the same quantity ; so that there is half a ton lessweight put upon 42 square yards of roof when the finestsort of slate is used, than if it were covered with the coarsestkind, and the difference of expense is very trifling. It mustbe remarked, that it owes its lightness, not so much to anydiversity in the component parts of the stone from which itis split, as to the thinness to which the workmen reduce it;it is therefore not so well calculated to resist violent winds asthat which is heavier.

All the kinds before named partake of a similar mode oflaying, in as far as refers to the bonding or lap of one por-tion of the slate over another. The lap of each joint is gene-rally equal to one-third of the length of the slate, and theslater selects all the largest of the description about to beused, to be put on nearest the eaves. When the slates arebrought from the quarry, they are not so square as to beimmediately fit for use, but are prepared by cutting and sort-ing. The slater, to effect this, picks and examines the slate,observing which is its strongest and squarest end. He then,by holding the slate a little slanting upon, and projectingabout an inch over the edge of a small block of wood, seatinghimself at the same time on something which is equal to itin height, cuts away straight one of its edges : next, with aslip of wood, he gauges the other edge parallel to the same,and cuts off that also ; after which he turns it round andsquares the end. The slate is so far prepared, excepting itbe the turning of his tool round and pecking through it, onits opposite end, two small holes, which are made for thenails to enter when he lays it on the roof. All the quarryslates require this preparation from the slater. All slatesare put on with nails or screws, and two. at least, are assignedto each slate. The copper and zinc nails, or iron nails tinned,are esteemed the best, as being less susceptible of oxidationthan those of bare iron.

The preparation necessary for laying slates on roofs, con-sists in forming a base or floor for the slates to lie compactlyand safely upon. For the doubles and ladies, boarding isessential, if it be expected to have a good water-proof cover-ing. All that is required in the boarding for such slates is,that it be laid very even, with the joints close, the boardsbeing properly secured by nailing them on the rafters.

When the boarding is ready, the slater examines it, andprovides himself with several slips of wood, called tiltingfillets. A tilting fillet is made about two inches and a halfwide, three-quarters of an inch thick on one edge, and cham-fered away to an arris on the other. These fillets he care-fully lays and nails down all round the extreme edges of theroof, beginning with the hips, if any, and, if not, with thesides, eaves, and ridge. When these are all done, he pre-pares for laying the slates, and begins at the eaves first. Forthese he picks out all the largest slates, and places themregularly throughout, setting their lower edges to a line ;

to tl,e

after which, he secures them by nailing them downboarding. He then selects such slates as will form tn eQfl .to the under sides of the eaves. This part of the w ° r . c |, b«sists in placing another row of slates under those , w . j n ts Shas previously laid, so as to cross and cover all their . eh * re

such slates are pushed up lightly under those

above them, and are seldom nailed, but left depende* 1their support on the weight of those above them. af> fiief

and a*'

for

own weight on the boarding. The countesses,

descriptions of slates, when intended to be laid in g n j s )iedmanner, are also laid on boards. When the slater has g j a teSthe eaves, he strains a line on the face of its upp eparallel to its outer edge, and as far from it as 1 ^ s hi*Hsufficient for the lap of those slates which he * nteJ ^;tb tl> 6form the next course, which is laid and nailed even ea veS-line, and crossing the joints of the upper slates of .jj (beThis lining and laying of the slates is continue ^ geJ . v ingslater gets up close to the ridge of the roof, 0 ^ ] a ysthroughout to cross the different joints by the slate ^ ovV edon, one above another. This method is uniformly j )a { a r0in laying all the different kinds of slates, excepting A'*called the patent slates, as will be hereafter eX P ain vv ,i, a t f* rethe larger kinds of slate are found to lie firmly 0 ”__ jrl11 eiitiy

best

freq uel

tb®

called battens, in consequence of which they are t ] ja n n*-made use of for the sake of economy, being cheap a n ar 'smaller slates laid on hoarding. A batten consiss half> ° rrow portion of deal wood, about two inches an t ^ e nthree inches wide ; three of which are common fattens ^of a deal. When countesses are to be la*d^

“"“'kiut

..__ 0n ’ n b adefi aa, f

three-quarters of an inch in thickness will !? e a ; er ki llC * °substance for them; but for the larger and iea , 00 r js toslates, inch battens will be necessary. When a er sonbattened for slates, the slater himself is the ® nce l" r ° jfix them, as they are not placed at a uniform 1 . teS ; » D .each other, but so as to suit the lengths of the ^ t j je r<*o^as these vary as they approach the apex or ridge judgit follows that the slater himself becomes 1 g j ate8 .where to fix the batten so as best to support t 16 se ] e cting 1 jThe patent slating, as it is called, consists m‘ A r °

largest slates, and those also of uniform i y'l that it® coto be covered with this kind of slate, requu ^ m ust ^mon rafters be left loose upon their purlins, as |*® ce ts ,

placed so as to suit the widths of the slates, joi**^

sary to have a rafter under every one of the 11 ^^. t j je8e s j. a { j je

b«

these

Neither battening nor boarding is requu eu w ;,jtl) 0‘and the number of rafters will depend on * f e ,y w*l ^slates ; hence if they are of a large size, v ^.^errequired, and of course a great saving m ^ ]e r oof- , a9place, besides giving much less weight, upon cornB ien ce ’ fi,work of covering by this kind of slating* s vva „ th ebefore, at the eaves, but no crossing

- „ „ ,8 YV a >

or bondtn n t0 .

- , — — —.—, — — — . ~ , read 11 & . he*

the slates being uniformly laid, with each end* a

" butted up p a®

centre of a rafter, and they are all .-'being BV Laes-

throughout the length of the roof; the ra f e j w0 0 f tb® ^ sfl

as to come re;

gularly under the ends of

•y/o

uo uv t-yiuc icguiiui^ uuuw — nl nOS‘h& » V*

When the eaves course is laid, the slates co^F^_| ia lf * 1 - oe iscrewed down by two or three strong 1 *’ s 1

at each of their ends into the rafters,about two inches below their upper edge,as a lap for the next course of slates, w >* c *with its edges straight with the line

Aline^S^

this be>**o a bo* b ’

is l“ ld lay’".!lining’ f jsthe r 0 e t-

and this ■

ued till

with a lap, and screwing down, is continu re d-.’a then to be se - ot

finally covered. The joints are then to “® eet ; n g j 0,1 jing, which consists in covering all the * . sci' e " e

fillets of slate, bedded in glazier’s P utt /,’, e fillets aie ,jjeythrough the whole into the rafters. ^ ^ g j a teabout three inches wide, and as long *

W> 1 '