« AnteriorContinuar »
damp. The reason for striking the joint in this manner is that, the top edge of the brick being laid to the line, the bottom edge of the course is irregular, and the joint covering this irregularity secures a better appearance when looking up at the work. Fig. 126
is an example of the best method of struck or weathered joint. Fig. 127 is flat jointing, and Fig. 128 flat joint jointed. Fig. 129 is a gauged-work joint, which consists of lime run to a liquid state with water, and strained through a fine sieve; the joint
should be 32" only in thickness, hence the sieve should be at least 400 to the square inch.
Pointing.–Tuck pointing is the method of filling in the raked joint with specially prepared stopping, making an indentation in
Fig. 130. it with the tool called a jointer, and with the same tool inserting a white or black putty joint about }" wide, and cutting off both edges to a rule with a frenchman, which is a knife pointed and turned up at the end. Fig. 130 is an illustration of this joint.
Bastard Tuck.—This joint is filled in with specially prepared mortar, and finished and made to project in the same material
with a thick-bladed jointer (Fig. 131). In this joint, again, the ragged edges are cut off with a frenchman.
Weather joints and flat joints, etc., are very similar to the struck joints, with the exception that the joints are put in after the work is finished, and with
specially prepared mortar. Struck joint is far stronger than pointing, but the latter gives an opportunity of cleaning down the work after the building is finished, thus securing a uniform appearance throughout.
If the drain be of stoneware, then the pipes should be of the best London make, truly cylindrical, straight and smooth, tested with the hydraulic test, and joined with Portland cement of the best description thoroughly cooled.
All drains, if practicable, should be outside the house, laid in a true line from point to point, with a fall of not less than 1' 0" in 60' 0". The most suitable for a soil drain is between 1' 0" in 40' 0" and 1' 0" in 60' 0". In drains that have too great a fall, the water travels so rapidly that it is often not of sufficient depth to float the solids and such-like matter to the outfall. Drains with too little fall, however, are liable to silt up, owing to the sluggish flow of water through them.
In laying the drain, it will be found convenient to set each pipe on bricks arranged on a 3" concrete foundation, to the proper fall. The spigot end of one pipe, being first chipped to form a key for the cement, is then placed in the flange of its fellow, the pipes being made to fit by packing up on the bricks, so as to ensure an even-flowing surface upon the inside of the drain.
The joints should be made in Portland cement properly and thoroughly trowelled. The drain-pipes are laid on bricks to enable the joint to be easily made, and that the joint may be seen when the drain is being tested. Concrete should then be carefully placed under and around the whole of the drain to a thickness of 6" in all, the top being rounded off to form what might be termed a concrete arch, thus relieving the drain of all weight of earth, etc.
The manholes, or inspection chambers, and disconnecting chambers are most reliable when built of hard stock bricks in Portland cement, and rendered inside to a very smooth trowelled face with Portland cement and sand. Fig. 132 is a plan, and Fig. 133 a longitudinal section, of a disconnecting chamber. A good arrangement for bonding the brickwork, so as to make the chamber water-tight, is to build two 43" walls, one backed in by the other, and both their bed and cross joints breaking joint with each other. (See Figs. 132 and 133 for plan and section of the bond.) In the latter it will be seen that one of
Fig. 132. the 4!" walls starts and finishes up with a half-course. There is no tie between the two 41" walls, and the strength will depend upon the mortar; but the work, having been thoroughly flushed up, will be found to form a most effective chamber.
It is very necessary that all drains should be easy of access, and so arranged as to be readily swept from end to end, and that the trap in the disconnecting chamber should have a sweeping eye. A plunger, or brush, the full size of the drain should be passed through, to see that no obstruction from cement is projecting upon the inside of the pipes. The drains should also be easy of inspec
tion throughout, from manhole to manhole, and disconnected from the public sewer by a properly constructed disconnecting trap (see Fig. 134). The principal feature of a disconnecting trap is that it should be self - cleansing, having a water-seal of at least 2", and
3" or 4" drop from the bottom Fig. 134.
of the channel to the surface of the water in the trap. A 6" trap of this description should not hold more than one gallon of water when at rest. An inlet for fresh air should also be provided in the disconnecting chamber.
Each house should have a separate drain to the public sewer, all branches being connected in the direction of the flow by means of manholes; but it may here be remarked that manholes inside the house are objectionable.
The main inspecting and disconnecting chambers must have curved channels to the branches, and all the extreme ends of the drains should be ventilated with lead pipes.
It is important that a lead pipe, and not an iron or rain-water pipe, be used for this purpose, because the moisture in the drain air causes the iron to oxidize, flake off, and form a deposit, which, when there is no water to wash it away, would in course of time choke the air-passage. The soil-pipe frequently serves as a ventilating pipe. These ventilating pipes must be taken their full size to the highest point of the roof, away from chimneys, windows, and other openings which would admit the sewer-gases into the house, and protected with copper-wire guards.
Rain-water and waste pipes must be intercepted from the drains with a properly constructed trap. This will be, in the ordinary course, kept supplied with water from baths, etc. This trap should also have a good water-seal, and be self-cleansing, the inlet connection entering the trap above the water-line, under the grating, and at an angle of about 45°. Traps not frequently supplied with water are liable to lose their seal by evaporation.
Where practicable, the intercepting trap from bath waste should enter the drain beyond the discharge from the soil, so that it may be utilized for flushing the drains. Where this cannot be done, it is advisable to use an automatic flushing tank, so that the drains may be flushed at least once in twenty-four hours.
The waste from the scullery sink should also be intercepted from the drain by means of a grease-trap, this also being flushed with an automatic flushing tank, which breaks up the grease and rushes it away through the drain.
At the completion of the work, everything connected with the system of drainage should be tested—the drains, by means of the hydraulic or water test; and the soil and waste pipes and fittings, by the smoke machine.
With respect to iron drains, a practical sanitary engineer, who is also a silver medallist and freeman of the Plumbers' Company, writes as follows:
“For a terrace house, where the whole of the drains have to be fixed inside, I should recommend heavy cast-iron drains, coated inside and out with Dr. Angus Smith's solution for the prevention of rust. The joints to be properly made with yarn, backed up with molten lead, and well caulked. In fact, I am strongly in favour of iron drains for every position, for when once made sound they will remain so for many years, which is not the case with stoneware drains. I have seen stoneware drains that have been properly laid, embedded in cement concrete, standing the hydraulic test year after year, and then for some unknown reason becoming thoroughly defective. But I have never found this the case with iron drains. Some will say that iron drains so quickly rust away, but I have not found it so where the pipes have been properly coated and covered with cement concrete.
“A short time ago I had to make some alterations to an iron drain laid twelve years ago, and found, in breaking it, that the coating of black was in perfect preservation, showing that a very thin coating of sewage and hardness from the water protected the black inside, and the covering of cement concrete the outside. An advantage would be gained by fixing a few expansion joints to an iron system of drainage, say to every chamber, to allow for expansion and contraction. If these joints are fixed in the chamber, the packing to the joints can be easily renewed.
“The by-laws of the various vestrys, etc., require that all soil and ventilating pipes be fixed outside the house; but I see no reason why they should not be fixed inside, and yet make a better