Part 2

Walls may be made damp not only by water rising in them, but by rain driving against them, and by water running down from the roof in consequence of the stoppage of a rain-water pipe. The latter cause is simple and easily remedied, but the former is far too frequent in cheaply-built houses. It may be prevented by having cavity walls, as they are called--that is, a double wall with a space between. There are several advantages from this. The air space, besides helping to keep the inner wall dry, is a good non-conductor, and so the house is all the warmer. There are other methods which may be used in addition to this, as cementing, plastering, or covering with slates or boards. There is some difference of opinion as to the advantage or disadvantage of the walls of a house being porous, as bricks are when dry; and Prof. de Chaumont seems to think that in our climate the porosity of the walls is not a point we need trouble ourselves about maintaining. Still, in Simpson’s opinion, with the ordinary arrangements of houses as regards supply of air and ventilation, some porosity of the walls is desirable. Without the freest and most perfect ventilation, walls absolutely impervious to air, and therefore to water in a gaseous form, will almost always be more or less damp on the inside.

Another source of dampness in dwellings, as pointed out by Eassie, is to be found in the practice of building the house walls close against the earth, without taking the precaution to erect a blind area-wall between the house wall and the earth excavation. Fig. 2 exhibits both these important improvements--the damp-course and the area-wall--applied to the same dwelling: _a_ represents the main wall of the house, and _b_ the area-wall, which is built against the excavated subsoil, leaving the space _c_ between the two walls; the thick black line underneath the floor-joist represents the damp-proof course, which interposes between the subsoil _d_, with the foundations built upon it, and the main wall of the house. This damp-proof course usually consists of a layer of pitch or asphalte, or slates bedded in cement, or specially glazed tiles, known as Taylor’s or Doulton’s manufactures. By the use of this impervious course, the upward passage of the ground water is effectually arrested. The intervening area _c_ it is also well to drain, but this water should never drain into the soil drain, if avoidable, and certainly not until it has been thoroughly disconnected. There should always, also, be a current of air introduced from the outer air, by way of ventilators put at the top of the blind area _c_, and an air brick placed above or below the damp-proof course--preferably above--in order that the space between the ground and the joists or stone flooring of the basement may be thoroughly ventilated. This ventilation is shown by the arrows between _e_ and _e_. Such air currents should always be provided under floors, whether there be a basement or not, and also always between the joists of the upper floors, and in the roof, in order to ward off dry-rot and ensure a constant circulation of air. (Eassie.)

_Roof._--The first detail to be decided on is the “pitch” or slope to be given to the roof, and this will depend both on the nature of the covering material and the character of the climate. In the tropics, where rain falls in torrents, a flat pitch helps to counteract the rush of water; in colder regions the pitch must be such as to readily admit of snow sliding off as it accumulates, to prevent injury to the framework by the increased weight. The pitches ordinarily observed, stated in “height of roof in parts of the span,” are as follows:--Lead, 1/40; galvanized iron or zinc, ⅕; slates, ¼; stone, slate, and plain tiles, 2/7; pantiles, 2/9; thatch, felt, and wooden shingles, ⅓ to ½.

In country districts the roofs of cottages and outbuildings are frequently covered with thatch. This consists of layers of straw--wheaten lasts twice as long as oaten--about 15 in. in thickness, tied down to laths with withes of straw or with string. Thatch is an excellent non-conductor of heat, and consequently buildings thus roofed are both cooler in summer and warmer in winter than others, and no better roof covering for a dairy can be found. Thatch is, however, highly combustible, and as it harbours vermin and is soon damaged, it is not really an economical material, though the first cost is small. A load of straw will do 1½ “squares” of roofing, or 150 superficial feet. First class thatching is an art not readily acquired. While really good thatching will stand for 20 years, average work will not endure 10.

A convenient roofing material when wood is cheap and abundant consists of a kind of “wooden slates,” split pieces of wood measuring about 9 in. long, 5 in. wide, and 1 in. thick at one end but tapering to a sharp edge at the other. Shingles, or wooden slates, are made from hard wood, either of oak, larch, or cedar, or any material that will split easily. Their dimensions are usually 6 in. wide by 12 or 18 in. long, and about ¼ in. thick.

Roofing felt is a substance composed largely of hair saturated with an asphalte composition, and should be chosen more for closeness of texture than excessive thickness. It is sold in rolls 2 ft. 8 in. wide and 25 yd. long, thus containing 200 ft. super in a roll. Before the felt is laid on the boards (¾ in. close boarding), a coating composed of 5 lb. ground whiting and 1 gal. coal tar, boiled to expel the water, is applied, while still slightly warm, on the boards themselves; the felt is then laid on, taking care to stretch it smooth and tight, and the outside edge is nailed closely with ⅞ in. zinc or tinned tacks. The most common application to a felt roof is simple coal tar brushed on hot and sprinkled with sharp sand. It is not well adapted to dwellings.

Dachpappe is a kind of asphalte pasteboard much employed in Denmark; it is laid on close boarding at a very low pitch, and forms a light, durable covering, having the non-conducting properties of thatch. It is sold in rolls 2 ft. 9 in. wide and 25 ft. long, having a superficial content of 7½ sq. yd., at the rate of 1_d._ per sq. ft. When laid, it requires dressing with an asphalte composition called “Erichsen’s mastic,” sold at 9_s._ 9_d._ per cwt., 1 cwt. of the varnish sufficing to cover a surface of 65 sq. yd.

Willesden paper is another extremely light, durable, and waterproof roofing material, which differs essentially from the 2 preceding substances in needing to be fixed to rafters or scantling, and requiring no boarding on the roof. It is a kind of cardboard treated with cuprammonium solution, and has become a recognized commercial article. It is made in rolls of continuous length, 54 in. wide, consequently, when fixing the full width of the card (to avoid cutting to waste), the rafters should be spaced out 2 ft. 1 in. apart from centre to centre, so that the edge of one sheet of card laid vertically from eaves to ridge will overlap the edge of the adjoining sheet 4 in. on every alternate rafter.

By far the most important and generally used roofing material in this country is slate. Its splitting or fissile property makes it eminently useful as a roofing material, as, notwithstanding the fact that it is one of the hardest and densest of rocks, it can be obtained in such thin sheets that the weight of a superficial foot is very small indeed, and consequently, when used for covering roofs, a heavy supporting framework is not required. Slate absorbs a scarcely perceptible quantity of water, and it is very hard and close-grained and smooth on the surface; it can be laid safely at as low a pitch as 22½°. In consequence of this, the general introduction of slate as a roofing material has had a prejudicial effect upon the architectural character of buildings. The bold, high-pitched, lichen-covered roofs of the middle ages--which, with their warm tints, form so picturesque a feature of many an old-fashioned English country town--have given place to the flat, dull, slated roofs. The best roofing slate is obtained from North Wales, chiefly in the neighbourhood of Llanberis. Non-absorption of water is, of course, the most valuable characteristic; an easy test of this can be applied by carefully weighing one or two specimens when dry, and then steeping them in water for a few hours and weighing them again, when the difference in weight will of course represent the quantity of water absorbed. The light-blue coloured slates are generally superior to the blue-black varieties. (J. Slater.)

Some architects bed the roofing slates in hydraulic cement, instead of having them nailed on dry in the usual way, which leaves them subject to be rattled by the wind, and to be broken by any accidental pressure. The cement soon sets and hardens, so that the roof becomes like a solid wall. The extra cost is 10 or 15 per cent., and it is good economy, considering only its permanency, and the saving in repairs; but, besides this, it affords great safety against fire, for slate laid in the usual way will not protect the wood underneath from the heat of a fire at a short distance.

Tiles are much used in some districts, and are often made of a pleasant tint; but a great objection to all tiles is their porosity, which causes them to absorb much water, rotting the woodwork and adding to their own already considerable weight.

Metallic roofing embraces sheet copper, sheet zinc, sheet lead, “galvanised” iron, and thin plates of “rustless” (Bower-Barff) iron. These materials are only used on flat or nearly flat spaces.

_Floors._--Tiles or flags are most frequently used for the floors of kitchens, sculleries, and lobbies. They serve this purpose very well, as they are easily washed and not likely to be injured, but the joints should be made impervious to moisture. In some parts of the country, concrete is used; this answers very well for the same purpose, but it is not good for bedrooms, as it is so cold to the feet. Wood makes the most comfortable floor for sitting or bed rooms, and the best is hard wood capable of bearing a polish. From its convenience and cheapness, common deal is used very generally, and too often in a damp and unsound state, so that the boards shrink and wide gaps are left between. This allows all the foul air from any space--as a cellar or a cavity between the floor and the soil--to ascend into the room. The boards ought to be as close together as possible, and any spaces left between them should be packed tightly with oakum. If this is done, the floors may be stained and varnished, when they can be swept and rubbed clean, and do not require such frequent washing as the ordinary unvarnished floors. This is an important gain, for there is no doubt that emanations rising with the damp from newly-washed floors are often most injurious. If a varnished floor is washed, it dries almost at once. Spaces must be left under the floors, on the ground level, if they are of wood, or they will soon decay; and they ought to be well ventilated. Ceilings, leaving a space between them and the boards of the room above, have come into use, most likely to deaden sound. They often fail of this, while affording fine playgrounds to mice, and even rats. Well-laid boards, of sufficient thickness, and plugged with oakum, would, as regards health, be preferable. (Dr. Simpson.)

_General Arrangement._--The chief points to be insisted on in a dwelling are enumerated by Simpson as follows:--Every room should obtain light and air from the outside, and there should be free communication from front to back, so that a current of air may pass through the house. What are called back-to-back houses are very objectionable, and to be carefully avoided. If there is a closet attached to the house, it should, as a matter of course, be ventilated by a window opening both above and below, and, if possible, should be built in a projecting wing or tower, and have double doors, with space between them for a window on each side, so as to have cross ventilation. When there is no closet in the house, it should be completely detached from it, and all piggeries, middens, &c., should be as far removed as possible. Speaking even of large houses, Eassie remarks that they are often very faultily planned in respect to the position in that portion of the interior which is usually appropriated to sinks and water-closets. In the basement, for instance, closets are often placed almost in the middle of the house, and the same mistake is committed on the floors above, a worse error by far; because then the closet would be placed on the landing of the stair opposite the best ground-floor, and chamber-floor rooms--the only ventilation from the closet-rooms being into the staircase, and consequently into the house.

Precaution against Snakes entering Dwellings.--There is no regular system adopted to prevent snakes entering dwelling-houses in Ceylon, as it is of rare occurrence to find any but rat snakes in European dwellings, and these are not venomous; but it is usual to clear away a portion of space about each bungalow and put on sharp gravel, and also to have coir matting laid down upon the verandahs, as snakes dislike crossing over rough surfaces such as gravel and coir. Trees should be at such a distance from the house (or bungalow) as to prevent the possibility of snakes dropping from the branches on to the roof.

Reducing Echoes and Reverberations.--The report of a committee of a Würtemberg association of architects upon the deadening of ceilings, walls, &c., to sound, gave rise to considerable debate, after which the following conclusions were reached. The propagation of sound through the ceiling may be most effectually prevented by insulating the floor from the beams by means of some porous light substance, as a layer of felt, a filling of sand, or of stone coal dust, the latter being particularly effective. It is difficult to prevent the propagation of sound through thin partitions, but double unconnected walls filled in with some porous material have been found to answer the purpose best. Covering the walls and doors with hangings, as of jute, is also quite serviceable.

To those who carry on any operations requiring much hammering or pounding, a simple means of deadening the noise of their work is a great relief. Several methods have been suggested, but the best are probably these:

1. Rubber cushions under the legs of the work-bench. _Chambers’s Journal_ describes a factory where the hammering of fifty coppersmiths was scarcely audible in the room below, their benches having under each leg a rubber cushion.

2. Kegs of sand or sawdust applied in the same way. A few inches of sand or sawdust is first poured into each keg; on this is laid a board or block upon which the leg rests, and round the leg and block is poured fine dry sand or sawdust. Not only all noise, but all vibration and shock, is prevented; and an ordinary anvil, so mounted, may be used in a dwelling-house without annoying the inhabitants. To amateurs, whose workshops are almost always located in dwelling-houses, this device affords a cheap and simple relief from a very great annoyance.

Echoes are broken up by stretching wires across the room at about 4-5 ft. above the heads of the audience. Often there is strong echo from the windows, which is lessened by the use of curtains, but with some sacrifice of light. Very thin semi-transparent blinds would check echo a good deal, but architects should not have large windows in the same plane; large unbroken surfaces of any kind are very apt to reflect echoes, yet we constantly see rooms intended for public meetings so built as to be spoiled by the confusing echoes.

Waterproofing Walls.--In many badly constructed houses with thin walls there is a tendency for damp to make its way into the interior. Several remedies for this inconvenience have been published at various times. The following procedure is described by a German paper as a reliable means of drying damp walls. The wall, or that part of it which is damp, is freed from its plaster until the bricks or stones are laid bare, next further cleaned off with a stiff broom, and then covered with the mass prepared as below, and dry river-sand thrown on as a covering. Heat 1 cwt. of tar to boiling-point in a pot, best in the open air; keep boiling gently, and mix gradually 3½ lb. of lard with it. After some more stirring, 8 lb. of fine brickdust are successively put into the liquid, and moved about until thoroughly disintegrated, which has been effected when, on dipping in and withdrawing a stick, no lumps adhere to it. The fire under the pot is then reduced, merely keeping the mass hot, which in that state is applied to the wall. This part of the work, as well as the throwing on of the river-sand against the tarred surface, must be done with the trowel quickly and with sufficient force. It must be continued until the whole wall is covered both with the tar mixture and the sand. The tar must not be allowed to get cold, nor must the smallest possible spot be left uncovered, as otherwise damp would show itself again in such places, and where no sand has been thrown the following coat of plaster would not stick. When the tar covering has become cold and hard, the usual or gypsum coating may be applied. It is asserted that, if this covering has been properly dried, even in underground rooms, not a sign of dampness will be perceived. About 300 sq. ft. may be covered with the quantities above stated.

An excellent asphalte or mortar for waterproofing damp walls or other surfaces is the following patented composition:--Coal tar is the basis, to which clay, asphalte, rosin, litharge, and sand are added. It is applied cold, and is extremely tenacious and weather-resisting. The area to be covered is first dried and cleaned, then primed with hot roofing varnish--chiefly tar. The mortar is then laid on cold with trowels, leaving a coat ⅜ in. thick. A large area is then coated with varnish and sprinkled over with rough sand. To frost or rain this mortar is impervious. The cost is 5_d._ per sq. ft., and for large quantities 4_d._ In the case of stone walls the following ingredients, melted and mixed together, and applied hot to the surface of stone, will prevent all damp from entering, and vegetable substance from growing upon it. 1½ lb. rosin, 1 lb. Russian tallow, 1 qt. linseed-oil. This simple remedy has been proved upon a piece of very porous stone made into the form of a basin; two coats of this liquid, on being applied, caused it to hold water as well as any earthenware vessel.

For brickwork, the _Builder_ gives the following remedy:--¾ lb. of mottled soap to 1 gal. of water. This composition to be laid over the brickwork steadily and carefully with a large flat brush, so as not to form a froth or lather on the surface. The wash to remain 24 hours to become dry. Mix ½ lb. of alum with 4 gal. of water; leave it to stand for 24 hours, and then apply it in the same manner over the coating of soap. Let this be done in dry weather.

Another authority says, coat with venetian red and coal tar, used hot. This makes a rich brown colour. It can be thinned with boiled oil.

A Devonshire man recommends “slap-dashing,” as is often done in Devon. The walls are, outside, first coated with hair-plaster by the mason, and then he takes clean gravel, such as is found at the mouth of many Devonshire rivers, and throws--or, as it is called locally, “scats” it--with a wooden trowel, with considerable force, so as to bed itself into the soft plaster. You can limewash or colour to your liking, and your walls will not get damp through.

Perhaps no application is cheaper or more efficacious than the following. Soft paraffin wax is dissolved in benzoline spirit in the proportion of about one part of the former to four or five parts of the latter by weight. Into a tin or metallic keg, place 1 gal. of benzoline spirit, then mix 1½ lb. or 2 lb. wax, and when well hot pour into the spirit. Apply the solution to the walls whilst warm with a whitewash brush. To prevent the solution from chilling, it is best to place the tin in a pail of warm water, but on no account should the spirit be brought into the house, or near to a light, or a serious accident might occur. The waterproofed part will be scarcely distinguishable from the rest of the wall; but if water is thrown against it, it will run off like it does off a duck’s back. Whilst it is being applied the smell is very disagreeable, but it all goes off in a few hours. On a north wall it will retain its effect for many years, but when exposed much to the sun, it may want renewing occasionally. Hard paraffin wax is not so good for the purpose, as the solution requires to be kept much hotter.

Curing a Damp Cellar.--A correspondent inquired of the editor of the _American Architect_ what remedy he would suggest for curing a damp cellar. The difficulty to be overcome, presents the questioner, in a new house is the wet cellar. Conditions present, concrete not strong enough to resist the hydraulic pressure through a clay soil. No footings under wall (which are of brick.) No cement on outside of wall. The water evidently, however, forces its way through the concrete bottom.

(_a_) Will reconcreting (using Portland cement) resist the pressure of water and keep it out?

(_b_) If not, will a layer of pure bitumen damp-course between the old and new concrete do the work?

(_c_) Will it do any good to carefully cement the walls on the inside with rich Portland cement, say 3 ft. high, to exclude damp caused by capillary attraction through the brick wall?

In reply to the above queries the editor gave the following hints, which are equally applicable to builders of new houses as to those occupying old houses with damp cellars:

It is doubtful whether even Portland cement concrete would keep back water under sufficient pressure to force it through concrete made of the ordinary cement. The best material would be rock asphalte, either Seyssel, Neufebatel, Val de Travers, Yorwohle, or Limmer, any of which, melted, either with or without the addition of gravel, according to the character of the asphalte, and spread hot to a depth of ¾ in. over the floor, will make it perfectly water-tight. The asphalte coating should be carried without any break 18 or 20 in. up on the walls and piers, to prevent water from getting over the edge; and if the hydrostatic pressure of the water should be sufficient to force the asphalte up, it must be weighted with a pavement of brick or concrete. This is not likely to be necessary, however, unless the cellar is actually below the line of standing water around it.