The Concrete Construction for Building Cottages
Considerable pains have been taken for the last fifty years to discover the best and cheapest method of building cottages; bricks, stones, wood, mud, plaster, and lately straw and bitumen, have all been selected. Sound bricks and good building stones, well incorporated with mortar of a good and binding quality, will last for centuries; while those of mud, clay, plaster or concrete are continually becoming out of repair, and therefore ought never to be introduced where sound construction is desired, and better materials can be procured. In our moist climate, unless great pains are taken in compounding such materials as clay or concrete, in constructing walls, and in protecting these against the effects of the weather, they will soon decay. Mud walls, however, made perfectly in the common manner, of clay well tempered and mixed with sharp sand, will last very many years.
The preceding view represents Rose Hill Villa, near Stockbridge, Hampshire. It is probably the largest and most important specimen of such a construction in England, and comprises dining and drawing-rooms, each 20 feet by 18 feet, morning-room, housekeeper’s-room, kitchen, back kitchen, pantry, excellent cellars and all requisite offices; five very superior bedrooms, two dressing rooms, a water-closet on the landing and ground floor, and five servants’ bedrooms. It has a double coach-house, harness-room, and stabling for four or six horses, and in the outhouses a four-roomed cottage for the coachman.
This villa was formerly in the occupation of Fothergill Cooke, Esq.,A the inventor of the Electric Telegraph, and is now the residence of Sir Augustus Webster, Bart.
The building is constructed of chalk concrete, and has stood the test of forty years’ exposure without any signs of decay. Mr. James Flitcroft sent in 1843 a view of the villa to the “Builder,” and thus described the construction of such houses in the locality:—The walls are carried above the ground two and sometimes three feet to prevent the damp from rising to the mud, which if wetted would scale off by the action of frost. The kind of earth used is fine chalk, dug from the surface; if timely notice of any building will permit, it is best dug in winter, that the frost may act upon it. Buildings formed of this material can be erected only in dry warm weather. The workmen in preparing this chalk for use put about a cartload of it together, throw water over it, and tread it with their feet, turn it over, again tread and turn it, until it begins to bind something like loamy clay; then let it soak a little while, when it is ready for use. The waller is able to put on a layer of about fifteen inches; he begins at one corner and goes round the building, putting one layer on another, taking care that the lower one is sufficiently dry to bear the upper. In buildings of two stories high, the walls are generally eighteen inches thick. When the walls are got up five or six feet, and pretty dry, the quoins are plumbed, and the walls dressed down a little, in order that the waller may see what he is about. A small short spade is the best tool for this purpose, with short handle and rather bent. The work is then proceeded with as before, until it is raised up to the square of the building, when the walls get their general dressing, ready to receive their coating.
Mr. Flitcroft describes Rose Hill Villa as coated with stone, lime-coloured and drawn. The columns of the villa are of brick. He states that there are several other buildings of this kind at Stockbridge, Winchester, and other places in the neighbourhood. He describes a better method of constructing such walls by the use of a moveable trough or box about 12 feet in length by 18 inches in depth. This trough rests on bearers put across the wall, with a mortice at each end wide enough apart to receive the sides, and the thickness of the wall; in these are inserted uprights to prevent the sides giving way, with others to go across the top. This mode of construction is however very ancient, and when done on a large scale the primitive method is still pursued.
This method is shown in the preceding engraving, which gives an elevation and section of a wall in process of construction, with the posts, b b, the moveable planking, c c, and cross pieces, d. It will be seen that three courses of bricks are put about every five feet in height. The figures here given are copied from a very old French work on Architecture and Building; they also show the manner in which roof construction was attempted with slabs of the same material, as shown in figs. 1 and 2: the building is supposed to be square, as shown by the dotted lines a, b, c, d.
The plan, elevation, and section given below represent a small tomb wholly formed of concrete slabs, the door alone being excepted. This little building forms really a solid concrete monolithic edifice.
A very common method of forming partitions, and even roofs in some of the agricultural districts in Hampshire, is first to put them up with strong wattle hurdles. They are double the size of the common hurdle, and made of a thicker material. When in their place, they are plastered over with concrete, and made about four inches in thickness; they very often require repair. It is said that concrete walls are subject to contraction and expansion, and speedily show vertical cracks at intervals, which in our damp climate would soon permit the wet to enter. There can be no question as to its strength as a building material, as some experiments conducted by the Institute of British Architects gave the following results—viz., “Concrete composed of two parts of lime, thirty-six parts of sand, and five parts of cement, can resist a crushing weight of four tons to the square inch, being twice the strength of Portland stone, eight times the strength of Bath stone, and sixteen times the strength of brickwork.”
In constructing cottages with concrete everything depends upon the goodness of the cement and the care with which it is used. The occupiers of these cottages are frequently their own operators; the work is generally too speedily performed, and the consequence is that the fruits of their labour are in most instances of but short duration.
For obvious reasons it is necessary that the greatest economy should be observed in the construction of peasants’ cottages, and for these reasons the apartments should always be on the ground floor, which will render it unnecessary to build them more than eight or nine feet high. Where mud walls are introduced, the lower they are made the better, in which case they should be made to batir on the outside so as to resist the pressure of the roof, the covering of which should project as much as possible, to throw off the wet and protect the walls. The chimney flues in these clay and concrete walls are formed of drain-pipes, which answer admirably. These humble dwellings should be paved with brick-on-edge paving laid on sand, which is much warmer, and more conducive to health than any sort of rough flagging, plaster, mud, or concrete floor. The latter, although much cheaper, can never be made to look clean. Foundations of clay or concrete walls should be of brick a few courses above the surface, and the walls when dry should be covered with a thick coat of plaster consisting of lime and sand, or what is still better, a coating of good Portland cement. This ought constantly to be kept perfect, as everything depends upon the goodness of the work. Concrete improperly mixed is not so strong as brickwork, but is mere rubbish; but when perfectly done it hardens with age, becoming like stone, impervious both to wet and frost.
Materials can be found in every locality. One of the principal constructors using such, Mr. Tall, who works with an excellently contrived apparatus, thus describes them:—“Clay, which may be burnt into ballast easily and cheaply, and is a most superior material for concrete; gravel, stone, crushed slag from furnaces, smith’s clinkers, oyster-shells, broken glass, crockery, or any hard and durable substance. Where sandstone or any flat stone is to be found, walls can be built even cheaper than of gravel concrete, as a labourer can break the stone.” He gives the proportions of materials used in houses then being constructed at Gravesend, as follows:
| £ | s. | d. | |
| 7 yards of burrs from brickfield, at 5s. | 1 | 15 | 0 |
| 7 yards of gravel stone, at 3s. | 1 | 1 | 0 |
| 1 yard of Portland cement, 16 bushels to the cubic yard, at 2s. | 1 | 12 | 0 |
| Labour, at 2s. per cube yard | 1 | 10 | 0 |
| Total | £5 | 18 | 0 |
Three cubic yards of concrete will build 60 yards of 9-inch work, at a fraction under 1s. 11d. per yard.
Concrete cottages have been built at Setting, in Kent, under Mr. Adkins, architect, that cost only 105l. per pair; the ground floor contained two rooms; with the usual larder and closets, and the upper floor three rooms and a cupboard; these cottages had gabled fronts and were picturesque in character. It would be an extra expense over the common method to construct floors and roofing of concrete; the advantage to be gained would be their fire-proof character.
In superior buildings the high tenacious power of good cement is repeatedly, it may be said commonly taken advantage of in the construction of roofs. These are formed by cementing plain tiles, and they have considerable strength. Roofs of 12 feet span, constructed in segmental form, rising three feet, and only of three plain tiles in thickness, successfully resist great pressure, and are durable in a very superior degree; but they require to be well tied in, and formed between iron girders connected together with iron tie rods, otherwise they sink and force out the walls. Roofs of cemented tiles have been constructed from 30 to 40 feet span, and have been found to answer well; hoop-iron bond, laid at intervals between the tiles, is a great advantage. The tenacious power of good cement was proved in a very high degree a few years ago by Mr. Brunel, in the construction of two semi-arches built of brick, springing from a pier or abutment 14 feet in height. One extended 50 feet in length, the other 38; the rise of the arches was 10 feet, the width only 4 feet 6 inches; a weight of about 40 tons was suspended to the extremity of the shorter arch without breaking it.
The result of this test proved that arches of 200 feet or 300 feet span, and probably more, might be constructed in the same manner at very moderate expense, without centering. Iron-hoop bond is said to nearly double the strength or holding power of the cement. Flat experimental beams have been constructed of brick and cement, with hoop-iron bond laid horizontally between the joints or courses of the brickwork, which have given equally extraordinary results.
Concrete for walling was extensively used in England at the beginning of the present century; it got into bad repute through failure of a river wall at Woolwich, where it was either badly done, some mistake was made, or it was unsuited to the position. The wall was constructed of blocks of concrete cast in moulds, and submitted to pressure while setting; a coating of fine stuff being applied for the sake of appearance, ample time having been allowed for the blocks to set and harden before use. The blocks were 1 foot 6 inches high, the binders and stretchers in the course being each 2 feet 6 inches long, the bed of the former being 2 feet, and of the latter 1 foot; the wall was built upon piles, its height above the piles being 24 feet; the thickness at bottom was 9 feet, at top 5 feet with a batir in front of 3 feet in 22.
The face of the wall was composed of blocks, as described, and rough concrete thrown in to complete its thickness, and that of the counterforts. After a frost it was found that this wall was seriously damaged, hardly a single block having escaped, and in many cases their whole face had peeled off to the depth of half an inch. The discharge of a drain from a height of 6 or 8 feet had worn away the lower courses to the depth of some inches. On a like wall at Chatham, similar but much more severe effects were produced.
The failure of this wall costing about 80,000l., was a serious matter, and for several years after architects looked upon concrete as being so much uneatable hasty pudding, considering that it was only beneficial when confined in a trench for foundations. Sir Robert Smirke used it in the foundations of the Penitentiary, Millbank, and Sir John Soane in 1830 used it in the foundations of the New State Paper Office (now pulled down) in St. James’s Park. Here the ground had to be excavated to a depth of 22 feet before arriving at a gravelly stratum; at each high tide the Thames filled the trenches with water, which remained in considerable quantity; as this was pumped out, the adjoining party walls of the buildings in Duke-street cracked so completely that they had to be taken down. The trenches were first filled to the height of two feet with broken stones and bricks from the old buildings, and then dry lime and clean river sand, with a large quantity of small broken granite stones, were thrown in from the height above. A body of concrete 8 feet in width by a thickness of 3 feet was thus formed; the water ceased to enter the trenches and the building was commenced.
Mr. G. Godwin, the editor of the “Builder,” in an essay on concrete which gained the first prize given by the Royal Institution of British Architects, appears to have been the first to suggest its use in walls above ground; and for these Portland cement concrete, when properly prepared, is without question an admirable material.