to a level after the walls are carried up and settled, before the floors are laid. Underneath the floor, where it is to be lathed and plastered for the ceiling, if for a common third-rate house the laths are nailed to the joist. If the ceiling is required to be somewhat stronger than usual, which is the case in good second-rate houses, quartering or ceiling-joists should be spiked below to the flooringjoists, about fifteen inches apart, which greatly strengthens the floor.* Bridge-floors are formed by truss-girders laid across the building from one wall to the other opposite, and placed about nine feet apart; care always being taken that the bearings at each end are on the piers and not over the windows, also avoiding the flues and fireplaces. This being done, binding-joists are then framed into the girders, their top edge being kept about five inches below that of the top of the girders, and six feet apart, with side-bolts at the ends, going through the girders, with nuts and screws, for the purpose of keeping the whole together. After this the bridgingjoists, which are generally square, are laid down across the top of the binding-joists, and spiked to the same to receive the flooring-boards. Then the ceiling-joists underneath are framed in between the binding-joists by means of chase mortices, which joists are to receive the laths. In good firstrate houses, short pieces of board are always laid in on slips above the ceiling-joists, and on them a pugging made of chopped hay, mixed up with common earthy clay and a sprinkling of lime, to prevent or deaden the sound. In the ground-stories of houses of the first magnitude, where the servants' offices are in the basement below, as in London, arches are sometimes turned in between the joists, with tiles made for the purpose, but in this instance the joists are usually of iron, and placed from five to six feet apart. In laying down flooring-boards, it is best at all times to have the joists so as to place the boards parallel if possible to the fireplaces, for the purpose of avoiding walking across them. Nothing of this kind is more objectionable than in passages. But in groundfloors the joists are generally laid the reverse way of the floors above, as a cross-tie to the walls of the building.+ The last and the finish of a floor after the skeleton frame-work, is that of the planed boarding over; but previous to performing this, the joists must be wedged up perfectly level, and a lath nailed on the joist along the doorways before the floor is laid, otherwise the doors will be liable not to clear the floor. There are three general kinds of boarded floors distinguishable from each other; namely, folding, straight-joint, and dowel. The folding is performed by a board being first nailed down a little less than three or five boards off from the first nailed board, the two inner ones are then raised in a ridge in the middle, a short board laid across and jumped on, which then brings them down on the joist, after which each board is nailed to the joist. In the second kind, the boards are laid down separately and drawn close by a lever, and then nailed on one side and one edge. The third kind of flooring is held together by dowels, and each board nailed on the edge to the joist. These floors are generally formed with narrow boards of wainscot, chestnut, or clean deal battens.§ * Where a floor in a public building is required to bear a certain weight occasionally, such as an assembly of people or guests at a public dinner, the calculation must be made on each joist, supposing the weight to be equally distributed along it from one end to the other, and not taken in the middle, which would lead to a false conclusion.-(See Tredgold on the Strength of Timber.) To avoid this, the girders are sometimes obliged to be put crossways in the building; here the ends of those important timbers should always be tarred over, to protect them from decay arising from the damp of the wall.—(B.) If either of the outer walls on which the joists happen not to rest should be considered weak, it is best to tie them by short trimming-joists from the common joists to the walls.-(B.) § At the end of the sixteenth century wainscot floors were much in use, and in some manor-houses chestnut. At Cotele, in Cornwall, an ancient house, and also at Mount Edgecomb, in Devonshire, the floors are of chestnut, but now such floors are seldom to be met with.-(B.) Since the use of carpets came into fashion in England, the boards of floors have not been so much regarded.* In the early period of our history the flooring-boards were generally coarse; and the floors were covered with rushes even at the close of Elizabeth's reign, although instances of tapestry cloths for the feet to rest upon occur as early as Edward I. It does not appear to have been the custom at any time to leave floors bare.t Dr. Bulleyne, in his Bulward of Defence, printed in 1562, observes, “that rushes which grow upon dry ground be good to strewe in halles, chambers, and galleries to walk upon, defending aparel, as traynes of gownes and kertles from the dust;" and Decker speaks of bulrushes being applied to the same use.‡ The boarded floors at this period were rough, but of substantial workmanship, and the joiners' work rude. At Godman-hall, Cumberland, built in the thirteenth century, the boards or planks of the floor above the principal story were grooved into each other, to prevent assaults above from the borderers. The upper floors of Salmesbury-hall, built in 1532, were of massy oak. Many of the floors of the early houses in England, built by the Romans, were of paved glazed mosaic earthenware tiles; but these tiles were of various colours, and seem to have been laid with great attention, many of which have been found on digging up old foundations in different parts of the kingdom; several have lately been met with of this description at Exeter, some of which are in the author's possession. The common floors were laid with tesselated pavement, which have also been met with; these floors are formed with small pieces of a hard white stone, each piece about one inch, and the whole laid close to each other in compact cement. The mosaic tiles are generally about six inches square. The refectory or dining-hall at Christchurch, Oxford, built in the reign of Henry VIII., was paved with green and yellow tiles: the whole number, we are told, was two thousand six hundred, * The French are not partial to carpets, therefore their best floors are very handsome-an instance of which may be seen at the British Museum. The floor of the Picture Gallery at Buckingham Palace is also laid in the French manner, and consists in being framed in small diagonal squares; but here they are formed with different English woods, which has a rich. and varied effect.--(B.) + Our poets, particularly Chaucer, Ben Jonson and Shakspeare, all speak of reeds and rushes being laid in principal apartments, and sometimes being strewed with herbs and aromatic flowers. "Sweet lady, I do honour the meanest rush in this chamber for your love." ‡ Lævinius Lemnius, a physician and divine of Zealand, visited London in the sixteenth century, and wrote an account in Latin of his travels, which was translated by Thomas Newton in 1576. He speaks with great admiration on the cleanliness of the English, and adds, "their chambers and parlours strewed over with sweet herbs refreshed me; their nosegays, kindly intermixed with sundry sorts of fragrante floures in their bed-chambers and private rooms, with comfortable smell, cheered me up, and entirely delighted all my senses."--(T. N.) This is the fashion at the present day even in the bed-rooms of the inns in France, which the traveller has good reason to remember, being rendered slippery from their high polish.-(A.) Tiles in squares or dies in checker-work, one square after another; those tiles were of various figures, formed by indents or sunk work from the mould, (like the Egyptian bricks,) which were afterwards filled up with various colours and painted, and then varnished and baked: red and green appear to have been the prevailing colours.-(B.) 1 Red. SS and each hundred cost three shillings and sixpence. The hall at Hampton Court, and a room at Wimbledon in Surrey, called the lower Spanish room, were "floored with paynted tyle." DISSERTATION XVII. ON THE FORMATION OF PARTITIONS. "The strength of a partition depends more on the just position of the braces, than on the substances of the timbers." TREDGOLD's Carpentry. There is more to be considered in framing partitions which divide the internal part of a house into rooms, than is generally supposed or attended to. These rough frames require to be constructed upon scientific principles, as they frequently have to bear not only a great part of the weight of the floor above them, but in many instances much of the weight of the roof. It is for want of an early attention to these parts of the carcase of the house that we frequently see cracks in the plastering at the angles of the rooms and along the ceilings, and such general settlements taking place as often to occasion the doors to drag on the floor; an evil which can never after be remedied without lifting floor after floor by a screw-jack, and to do this much of the work must be taken to pieces and constructed anew.* The proper purpose of timber partitions is for separating the stories of buildings into various divisions, and generally the upper into more than that of the lower part of the house, by which the perpendicular rests are departed from; yet, if formed on true principles, they will subsist without casting any weight on the floor, and even the ceilings may thereby be more firmly upheld; for a quarter-partition properly formed, contains truss-work as capable of upholding a floor, as the truss of a scientific roof is of upholding a ceiling of prodigious weight and span. Partitions should always be well braced, and these braces so disposed as to throw the superincumbent weight laterally towards the side-walls; but braces are too often considered by many of the present builders more in the light of economy in saving materials, by the means they afford them of using in short pieces, than adopted as a great principle of discharging the preponderating weight above from that of the floor on which the partition rests.† Slight cracks in a house sometimes occur near the ceiling, where even the partition has been well braced, occasioned by the shrinking of the joist on which the partition is seated; for this reason, a house is much better to stand some time in carcase before the joiner's work is done, for the wind during that time passing through the building will season the timbers. The shrinking of the joists on each floor, though but one-eighth of an inch, is considerably increased in the partition up through the house, where the joists lay on the partition heads; for one-eighth of an inch on the ground-floor makes a quarter of an inch on the next floor, and so on in the same multiplying ratio; for this In the construction of quartered-partitions which have much burthen to bear, it is best to have a tie-plate over each doorway, and to form a strong truss in the roof, immediately over each quartered partition; thus all dangerous settlements in the partitions may be prevented: any one of these trusses, if constructed strongly enough, may be made to carry all the burthen of the floors of a house, either by bearing the weight on its back or by suspension to it. If an old house has sunk in its centre from the weight of the floors upon an ill-constructed stack of partitions, it will in general be best to insert a strong truss above the heads of the doors in the two-pair story. Wrought-iron bars may be fastened to the roof on each side the king-post, carried down to each partition, and fastened by nuts and screws, thereby suspending the partition to the roof, which is a most excellent method.--(B.) + It is not my purpose here to give detailed carpentry for the operative mechanic, but only taose general principles which are sufficient to guide the builder in the construction of those parts of his building.—(Author.) reason some builders have considered it more advisable that partitions should have no sills, but the studs be carried down between the joists, and framed into the head of the partition immediately below. Though this is correct in idea, nevertheless I prefer having the sill, the partition being much stronger, but at the same time placing blocks of wood on their ends between the partition-head below and the sill above, which prevents both shrinking and sinking. Where a partition is to be framed so as to have a door leading from the stairs into the drawing-room, and also with folding-doors between the front and back drawing-rooms, the head of the partition in this case should be well trussed with oak, having a straining-beam in the middle, two queen-posts, and two braces, with lead at the abutment-joints; these pieces are then to be forced together with benchscrews, and kept in their places by wedges passing through the auxiliary head.* DISSERTATION XVIII. ON THE PRINCIPLES AND GEOMETRICAL FORMS OF ROOFS. "A little stronger than strong enough."-OLD Builder. There is no part in the whole scope of the architect's profession that is more important, or more requiring a deep consideration, than the roof; and there is this satisfaction for the man of mechanical genius, that there is none in which there is greater room for improvement. It is necessary first to comprehend perfectly the purpose of this part of a building, and then what is generally known concerning its structure. Its purpose is to cover the house above, and to carry off the rain, sleet, hail, or snow that falls, and is generally more considered by the builder as an object of utility to be attended to, than as one of beauty, although differently treated by the tasteful architect. Its general form is that of one great triangle resting on the side-walls, and whose principal rafters convey to the reader's mind that passage in the Iliad, where Ulysses and Ajax are described as wrestling, and is thus translated by Pope : All the plates and cross-ties of such partitions should be made to camber very considerably, the curve gradually increasing as the stories ascend; and all the floors, ceilings, and door-heads should conform to this camber, which should not be less than half an inch on the one-pair floor, an inch on the two-pair floor, and an inch and a half on the three-pair floor, and so on in proportion. If this precaution be not taken, you may be sure in less than two years to find the floors and ceilings fall out of level in their centres, as much both from the shrinkage of the timber, and from the strain upon it from burthen. The door-jambs fixed in such partitions invariably strain out of square at their angles more or less, in proportion to the dryness of the timber, the skill exercised in trussing the work, and the degree of burthen cast on the partitions; therefore all such jambs should have their heads fixed somewhat out of level, so as to settle permanently to a correct square form, instead of being fixed level, so as to settle permanently out of square. In general, plates immediately above the floors should be omitted, as the more horizontal timber there is, the more shrinkage there will be, and consequently the more settlement; and such plates mostly require to be cut through for doorways; they are rarely of use as ties to the work. Under each end of each truss a templet of granite street-curb, three or four feet long, or some other durable and incombustible fulcrum, should be set : these should be strongest and longest where the trusses act with most energy.— (A. Bartholemew.) Wainscot partitions are such as are framed in panel-work.' These partitions did not come into general use till Elizabeth's reign, though panelled framework to walls was known before, as we have it on record. (MS. Cotton. Vitellius.) "That the house of Richard Fermor, of Eustove, gent., (temp. Henry VIII.) they sydes of the perlor were celyd (panelled) with wenskot." And at Wressil Castle, the sides of the rooms were ornamented with wainscot, containing a great profusion of ancient carving, finely executed in wood, exhibiting the ancient bearings, crests, badges, and devices of the Percy family, (so renowned in Chevy Chace,) in a great variety of forms, set off with all the advantages of painting, gilding, and imagery. -(Dr. Percy.) It is a misnomer to call deal-framed panel partitions wainscoting, it being evidently a contradiction in terms, but such is the general practice among builders.~(B.) "Amid the ring each nervous rival stands, Embracing rigid, with implicit hands: Close lock'd above, their heads and arms are mixt; Below, their planted feet at distance fixt, Like two strong rafters, which the builder forms, Their tops connected, but of wider space Fixt on their centre stands their solid base." (Book 23.) Within this great triangle others are formed, each tending to resist the pressure of the inclined principal rafters, and to uphold the tie-beam, which keeps the roof from spreading, and so constructed as to throw the weight right and left on the side-walls. One great caution is required, that the roof be neither too heavy nor too light, although the old adage says "a little stronger than strong enough;" if it is strong enough, surely that is all that can be required; beyond that a roof is a load on the walls, and a useless expense laid on the proprietor.* When a roof is heavy by its unnecessary quantity of timbers it has a tendency to crush the sidewalls all superfluous and unnecessary thickness in the timbers becomes likewise part of the load. When the roof is slight, the timbers on the contrary are liable to swag in different parts, and become incapable of keeping the walls together, if not at the same time to thrust them out of their perpendicular; every extremity is therefore to be avoided. Thus he who knows well the strength of timber, and how to proportion each piece according to what it has to bear, with the nature of the thrust and the resistance, how to be applied in the distribution of his braces and struts, is best able to construct a roof. This great component part of a building requires something more to be thought on than merely to cover and carry off the rain which falls on the house; it must be considered likewise as a support for the walls by holding them together. This, on the other hand, it will not do if improperly braced, or too slight in the timbers employed. In practice the great and common evil is, that generally the timbers are too large and too heavy; that architect will therefore render the most acceptable service to his employer who shall show how to retrench and execute his roof with a small quantity of timber, as he will by this take off an unnecessary load from the walls, and a large and useless expense to the owner.+ The forms of roofs are various, but the four following are the most general. First, the common spanroof, which is like the Roman letter A: the second, that of the letter M, but more properly like the M inverted; this roof has a gutter in the middle. Thirdly, the kerb or French roof, as thus ‡, which rises with little inclination from the gutter of the parapet till it reaches the kerb head of the garret windows, which there forms an eave, and then slopes inwards, till at last it forms a common ridge in the middle in the usual way. The fourth is a truncated roof of this figure, which instead of rising to a * By this we do not mean that the roof is to be calculated merely as to its own weight, for it will occasionally have to carry a body of snow.--(B.) Nothing shows the skill of a carpenter more than the distinctness with which he can foresee the changes of shape which must take place in a short time in every roof. A knowledge of this will often correct a construction which the mere mathematician thinks unexceptionable, because he does not reckon on the actual compression which must obtain, and imagines that his triangles, which sustain no cross-strain, invariably retain their shape till the pieces break. The sagacity of the experienced carpenter is not however enough without science for perfecting the art. But when he knows how much a particular piece will yield to compression in one case, science will tell him, and nothing but science can do it, what will be the compression of the same piece in another very different case. Thus he learns how far it will now yield, and then he proportions the parts so to each other, that when all have yielded according to their strains, the whole is of the shape he wished to produce, and every point is in a state of firmness. It is here that we observe the great number of improprieties. The iron straps are frequently in positions not suited to the actual strain on them, and they are in a state of violent twist, which both tends strongly to break the strap and to cripple the pieces which they surround.—(Dr. Robinson's System of Mechanical Philosophy, vol. i. p. 60.) See the roof on the British Museum, which is a French building. |