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Bricks.—The (name the bricks to be used) to be good, sound, hard, well-burnt, square, true in shape, with sharp arrises and even surfaces, made equal to the sample to be submitted to, approved by, and deposited with, the architect. Facings.—Face the (here state which portions) with Messrs.
first quality (here state the kind of bricks), a sample of which is to be approved by the architect.
Glazed Facings.-Face (here state where) with Messrs. first quality (state colour) bricks.
Purpose made Moulded Bricks.—The moulded strings, cornices, etc., to be of (here state the maker and description), as shown on detail.
Rubbers or Cutters. The bricks for all gauged arches, strings, cornices, pilasters, etc., where shown, to be of Messrs. No. first quality.
Lime Mortar.- To be composed of three parts clean sharp pit sand to one part of (name the lime), to be mixed and used the same day.
Cement Mortar.— The cement mortar to be composed of one part Portland cement of the best quality, well-burnt, weighing 112 lbs. per strike bushel, passed through a sieve of 2500 to the square inch without leaving more than 10 per cent. behind, and being capable of resisting a tensile strain of 350 lbs. per square inch after seven days' immersion in water, and three parts clean sharp pit sand, to be mixed with just sufficient water for their incorporation, and used immediately after mixing. No mortar that has partly set
be re-mixed for use. Putty for Gauged Work.—The putty to be of chalk-lime mixed with water, and run through a fine sieve to the consistency of Note.—All other materials to be stated in a similar manner, the object being to ensure that the quality shall be quite up to the manufacturers' standard.
WORKMANSHIP. Work generally.—The whole of the work to be carried up in (here state the bond) with mortar as specified, perfectly level, plumb, and true. The bricks to be well wetted before being used, each course to be properly flushed up, and no four courses of brickwork are to measure more than (here state the allowance for joint) in height, in addition to the collective height of the bricks, and no one portion being raised more than 5' above another at one time.
Footings.--The bottom course of footings to be twice the thickness of the wall to be built, setting off on each side in offsets of 21", and to consist as far as possible of heading courses on each side.
Damp Courses.—The whole of the walls to have a layer of (here state the damp-resisting material), laid horizontally as a damp course 6" above ground-line, or where shown on drawings.
Facings. The facings to be properly bonded with the general work, the beds and perpends to be kept perfectly true, and the joints (here state whether to be neatly struck or raked out and pointed, etc.), and all to be kept thoroughly clean.
Gauged Work generally. All arches and embellishments where shown to be accurately rubbed and cut, and set in fine lime putty, the joint not to exceed 3" in thickness. The work, wherever possible, to be joggled and run in with Portland cement grout, and at completion to be cleaned down, leaving all mouldings, etc., perfectly true, and according to detail.
External Arches not Gauged.—The external arches to be formed with picked (here state the bricks), fair axed as shown, set in cement, and (here state the finish, e.g. struck or raked, etc.).
Relieving Arches.—Turn relieving arches over all lintels in (here state the number of rings) in cement, with skewbacks formed at the ends of the lintels and according to the given rise.
Chimney Openings, Flues, etc.—Build in over each fireplace opening a }" x 2}" wrought-iron caulked chimney bar, carried 9" each end into the jambs, and turned up and down 2" in addition. Turn a rough brick segmental arch over the same in two rings, and carefully gather over the opening to form the flue. The flues to be carried up the given size throughout, with no sharp curves
or bends, and to be properly pargeted as the work proceeds. Leave holes in the outside faces of the breasts where bends occur, so as to admit of cleaning out after execution, also render the whole of the chimney backs to fireplaces.
Sundries.- Do all rough and fair cutting.
Cut away, etc., as required for other trades, and afterwards make good.
The above is not a complete specification ; many other items will occur according to the features of the work to be carried out, and must be specified in a similar manner.
USEFUL MEMORANDA, FROM
A ROD of brickwork laid four courses to 12" requires 4360 stocks, and 71 cubic feet of mortar consisting of 1 yard of stone lime and 3} yards of sand.
The weight of a rod of brickwork is approximately 15 tons.
27 cubic feet, or 1 cubic yard, equals a single load of sand, earth, or rubbish.
2 cubic yards equal a double load.
A cubic yard of mortar requires 9 bushels of lime and 1 load of sand.
In estimating the quantity of water for making mortar, allow one-third of the total bulk.
London stocks measure 82" x 4" x 23", and weigh 60 cwts. per thousand.
Earth and clay increase in bulk about one-fourth when dug; sand and gravel, one-tenth (Hirst).
33 cubic feet of ballast, 3} bushels of Portland cement, and 30 gallons of water make 1 cubic yard of concrete (Rivington).
The following weigh 1 ton: gravel, 19 cubic feet; river sand, 20 cubic feet; pit sand, 21 cubic feet; Thames ballast, 22 cubic feet; clean shingle, 23 cubic feet (Hirst).
1 cubic foot of water = 6.2355 gallons; 1 gallon of water weighs 10 lbs.; :: 1 cubic foot of water weighs 62355 lbs.
In battering or retaining walls for earth, the base of the wall should not be less than one-fourth, and the batter, or slope, not less than one-sixth, the vertical height (Dobson).
Practical rule for thickness of walls to retain water-
x 0:3 (Rivington). Pillars of brick should, as a rule, be limited in height to twelve times their least thickness at the base to obtain their full strength.
A safe limit against crushing for best stock brickwork is as underMortar, composed of Portland cement 1, sand 2 = 10 tons Lias lime 1, sand 2
5 Grey stone lime 1, sand 2 = 3. The work to be flushed up solid with mortar (Hirst).
Ordinary firm earth will safely bear a pressure of 1 to 1} ton per square foot, while moderately hard rock will bear as much as 9 tons (Rivington).
To find the area of an egg-shaped sewer, multiply the internal height squared by 0:525 as a constant (Rivington).
In reckoning the thickness of arches, the spans being from 10 to 25 feet, allow half a brick for every 5' of span (Rivington).
Efflorescence on walls is formed by a process known as saltpetring. In appearance it is like hoar-frost, and is caused by the sulphur in the coal used in burning, converting the lime or magnesia in the bricks or cement into sulphates. These, upon the application of water, are dissolved; after which, the water evaporating leaves them in the form of crystals on the surface.
Bricks burnt with coke or wood do not saltpetre.
Circles.—To find the area, square the diameter and multiply by 0.7854 or multiply the circumference by the diameter; and divide by 4. To find the circumference, multiply 3.1416 by the diameter.
The following tables show at a glance the thickness of walls for (1) dwelling-houses, (2) warehouses, as tabulated from the London Building Act by Hirst :
Height up to
Length up to 45
One story, 30"
Top story, 13"