"When a joint occurs between a horizontal surface, such as a lead flat, and a wall or chimney, the lead is dressed up against the masonry to a height of from 5 to 7 inches, and the joint covered by an apron, as at a in Fig. 457.
Raking Flashings are required to cover the joint which exists where the slope of a roof is cut into by a wall or chimney.
There are two methods of arranging the flashing.
1. The strip of lead required should be about 16 inches wide; of this, 8 inches lie 1 upon the slates; 6 inches are turned up against the masonry, and the remainder into a raglet parallel to the slope, and secured there.
The section, Fig. 471, shows this arrangement; it is taken through the lap of the slates where there are, of course, three layers.
An additional precaution is sometimes taken by forming a cement fillet, of triangular section, under the lead flashing in the angle between the slate and the wall, so that if the flashing is blown up, the joint is still kept secure until the lead is replaced.
1 This is when countess slates are used. The width should be 3 inches more than half that of the slate, so as to overlap the first side joint 3 inches.
2 Sc. Doubling.
2. In the second method a tilting fillet about 2 inches wide and 3/8 inch at the thickest part is placed from 2 to 4 inches from the chimney or wall, and the lead dressed close over it, and down upon the roof boarding, which is sometimes rebated out 1/2 inch in depth to receive it, then turning up against the wall and under a cover flashing or apron. The slates lie over the lead.
Fig. 472 gives a section of this method as frequently carried out. It will be seen that it virtually forms a sort of gutter down the side of the chimney, and it is sometimes so described. This arrangement requires a little more lead than the other, but secures it better, for the lead, being under the slates, is not liable to be blown up. The wind is apt, however, to catch the exposed sides of the slates, and displace them. The remedy for this is to continue the slates right over the gutter until they nearly touch the chimney. When this is done, not only are they themselves protected from the wind, but they keep the sun off the lead, and prevent the latter from cracking.
The disadvantage of the arrangement last described is that when the gutter is covered by the slates its interior cannot easily be cleared out, and it becomes choked with dust and dirt, which lead the wet over the tilting fillet and into the roof boarding.
An elevation of a raking side flashing for a chimney is given in lug. 470.
Stepped Flashings are generally used where large and wide chimneys, or gable walls, cut into the slope of a roof.
The raglet, instead of running parallel to the slope of the roof, is in short horizontal lines, and the lead is cut into steps, the ends of which are at right angles to the slope, as shown in Fig. 473.
There are several ways of fixing stepped flashing.
The most common is to use lead some 16 inches wide, of which 8 inches may lie on the slates, 6 or 7 inches turn up against the wall, and the remainder into the raglet.
The section in this case would be similar to Fig. 471, and the elevation as in Fig. 473, except that the edge of the lead lying upon the slates would be seen.
Another plan is to form a side gutter along the wall, as in Fig. 472, securing the upturned lead in a stepped raglet, or covering it by an apron all in one piece cut to fit the steps,1 as shown in elevation, Fig. 473. Cover-Flashings in Separate Pieces. - A better flashing is formed as shown in Fig. 474 by hanging the stepped apron or cover-flashing in pieces (cf cf), one to each step, so arranged that the broad end of each piece overlaps the narrow end of the piece next to it down the slope, by 2 or 3 inches. These pieces may have a mean width of about 5 inches, of which an inch is secured in the raglet, and the remainder Jiangs over the flashing. The flashing itself will be disposed, as in Fig. 472, over a tilting fillet under the slates; the upturned portion need not be more than 3 or 4 inches high, and will be covered by the stepped apron.
1 Sometimes called a Skeleton Flashing.
Soakers,1 Fig. 475, are used instead of stepped flashing, and consist of pieces of lead (sk), worked in between the slates as they are laid; each piece is about 4 inches longer than the gauge of the slating (so that each extends under the whole exposed portion of a slate, and laps 4 inches over the next soaker),2 and about 14 inches broad, so that 6 to 8 inches may be under the slate, and 4 to 6 inches up against the wall, being covered by an apron or cover-flashing.
Fig. 475. Soakers.
Fig. 475a. Section.
This form of flashing is now in very general use. It is simple and secure; the wind cannot lift it, the lead cannot be stripped off without removing the slates.
1 Often also called stepped flashing.
2 Soakers are sometimes made the full length of the slates, but this takes more lead and the soaker is pierced by the nail which secures the slate above it.
In some cases instead of nailing the soakers as shown, they are secured by bending over an inch along the top edge, so as to clip the head of the slate. This is not a good plan as it requires more lead and prevents the head of the slate from lying close to the boarding.
Tingles l are fastenings placed at short intervals to prevent exposed sheet lead - such as flashings which lie upon the slates, lead upon ridges, etc., from being blown up by the wind. They consist of strips of sheet lead which are nailed to the boarding, or hooked on to the head of a slate, and bent over so as to clip the edge of the flashing.
Two or three methods of constructing lead gutters are illustrated in Fig. 456, and the details connected therewith.
All gutters should have a current or fall of at least 1/100, and the joints between the ends of the sheets should be formed, when possible, by drips not more than from 8 to 10 feet apart.
The sides of gutters which abut upon walls or blocking courses should be turned up from 6 to 7 inches against them, and be covered by an apron. The side is, however, frequently fixed by simply turning its upper edge into a raglet; as the other edge is trammelled by the tilting fillet, this prevents free expansion and contraction under changes of temperature, and often results in splitting the lead. The ends of lead gutters are either bossed up - that is, neatly beaten into shape - or else formed with clog-ear joints, the lead being folded like the end of a paper parcel. These last are, however, not considered to be good plumbing, as the lead when bent double is liable to crack.
Bridged Gutters are formed with sheet lead laid upon boarding, supported by bearers. These bearers may either be framed in between the timbers of the roof or merely nailed to them. In the former case they are called trough or framed gutters; in the latter case V gutters.
Fig. 473 (being a section on GrH of Fig. 456) shows a trough gutter formed in the valley between two roofs.
It consists of a gutter bearer (gb) framed in between the pole plates of the roof, which are placed upon the principal rafters, so as to afford room for the gutter.
Boarding is fixed upon the gutter bearer, and upon this is laid the lead which passes up the slope on each side, and over the tilting fillet under the slates.
1 Sometimes called Bale Tacks, Bell Tacks, Bail Tacks, Clips, Lappetts, Binders, Tails. Sc. Latchets. 2 Sc. Box Gutter.
When a gutter is very deep and wide, so as to require a great width of lead, the sides sometimes stop short before they turn up the slopes of the roof, and are covered by an apron on each side hanging over the end of the rafter and the pole plate, as shown in Fig. 473.
A trough gutter fixed behind a blocking course is shown in Fig. 476, which is a section on K L, Fig. 456.
The bearer is framed at one end into the pole plate of the roof, the other end being supported by a gutter plate (gp).
One side of the gutter lead is turned up against the blocking course, and may be secured, as shown, by turning it into a raglet on the top.
It may, however, be covered by an apron, either similarly secured (see Fig. 147), or continued over the top of the blocking course and turned down about an inch over the front edge. In the last case the apron is kept in position by a conical-headed rivet leaded into the top of the blocking course.
The inner edge of the lead is turned up over the tilting fillet and boarding of the roof until it is higher than the top of the blocking course (or than the overflow pipe, if any), so that, in case the gutter should be choked, the water may flow over or through the blocking course, not over the inside into the building.
When the blocking course is high an overflow pipe may be introduced, as at OP in Fig. 469.
It is evident that the necessary fall for a trough gutter may be obtained by lowering the bearers gradually along its length, the width remaining the same throughout. The section, Fig. 476, is taken at a high part of the gutter, and the bearer is nearly up to the top of the pole plate; but in Fig. 473, which is a section at a lower point of the valley gutter, the bearer is nearly at the foot of the pole plate.