Dry stone wall

“ The greatest obstacle to the permanence of fresco painting is damp: hence, if the wall to be painted is covered with old mortar, the ingredients of which are unknown, this coat should be entirely removed until the solid brick or stone is laid bare. The rough coat then applied is composed of river-sand and lime, and of such thickness as is generally used in preparing the walls of dwelling-houses. The surface of this coat should be rough, but not uneven. Thus prepared, the wall should be suffered to become perfectly dry and hard ”

“ Dry areas, being far from sanitary, are seldom adopted now, and are being superseded by asphalt or cement applied to the face of the wall.
Moisture is prevented from soaking down from the top of the wall by using a covering of some impervious material in the form of a coping. This may consist of ordinary bricks set on edge in cement with a double course of tiles immediately below, called a “creasing,” or of specially made non-porous coping bricks, or of stone, cast-iron, or cement sloped or “weathered” in order to throw the rain off. ”

“ Where exceptionally large blocks of stone are available they have been utilized in an upright position, and occur at greater or less intervals along the thin walls of dry masonry. An example of this use was seen in a garden wall on the west side of Walpi, where the stones had been set on end in the yielding surface of a sandy slope among the foothills. ”

“ Earth should never be suffered to rest against walls, and the sunk stories of buildings should always be surrounded by an open area, so that the walls may not absorb moisture from the earth: even open areas require to be properly built. We will quote a case [178] to explain our meaning. A house was erected about eighteen months ago, in the south-east part of London, on sloping ground. Excavations were made for the basement floor, and a dry area, “brick thick, in cement,” was built at the back and side of the house, the top of the area wall being covered with a stone coping ”

“ The brick corner-work may be laid in dark or blue mortar with good effect in subduing the strong contrasts in color. Interior plastering should never be applied directly to the stone-work. Such walls do not readily conform to the sudden changes of the surrounding temperature, and are rendered damp and unwholesome from the moisture of the air being condensed upon them. They should be furred off, leaving an air-space between the stone-work and plastering, through the whole hight of the wall, and opening into the spaces between the rafters of the roof. ”

“ Stone requires no paint. Its color is a natural, therefore an agreeable one, be it usually what it may, although some shades are more grateful to the eye than others; yet it is always in harmony with natural objects, and particularly so on the farm where everything ought to wear the most substantial appearance. The outer walls of a stone house should always be firred off inside for lathing and plastering, to keep them thoroughly dry. Without that, the rooms are liable to dampness, which would penetrate through the stone into the inside plastering unless cut off by an open space of air between. ”

“ Where suitable stone is difficult to get in sufficient quantity, the exposed surface may consist of a shell the thickness of the stone and the inner portion of the wall be made of concrete or large stone bedded in concrete. When flue lining is necessary, it will serve as a form for the flue: otherwise a metal stovepipe makes a practical form, or the flue can be formed of brick laid on edge. The stones can be laid and the concrete deposited with the least trouble by building the veneer and flue only 6 to 8 inches high at one time. All masonry should be laid in mortar, as described on page 10. ”

“ Both kinds should be constructed of the smallest stones, so that the walls, being thoroughly puddled with the mortar, which is made of lime and sand, may hold together longer. Since the stones used are soft and porous, they are apt to suck the mois­ture out of the mortar and so to dry it up. But when there is abundance of lime and sand, the wall, containing more moisture, will not soon lose its strength, for they will hold it together. ”

“ When made of good clay, rightly tempered with sand, and well burned, they will in a wall remain for centuries, and as far as material is concerned, answer all purposes. Brick walls may be thinner than stone walls, but they equally require "firring off" for inside plastering, and in addition, they need the aid of paint quite as often as wood, to give them an agreeable color—bricks themselves not usually being in the category of desirable colors or shades. ”

“ A new mixture, cement and hair, or wood-fiber, has been put on the market, and is likely to be used extensively, for when properly used a stronger, harder, and more durable wall is secured than by using the ordinary stone lime and sand mortar. ”

“ Usually such cast-work was only used for foundations and cella walls, the upper parts being faced with brick; but in some cases the whole wall to the top was cast in this way and the brick facing omitted. In strength and durability no masonry, however hard the stone or large the blocks, could ever equal these walls of concrete when made with hard lava or travertine, for each wall was one perfectly coherent mass, and could only be destroyed by a laborious process like that of quarrying hard stone from its native bed. ”

“ The lime, in the state in which it comes from the kiln, is first ground to powder, and is then mixed with sand and gravel, and chippings of stone. The purposes for which the mortar is required indicate the coarseness and quantity of the intermingling gravel. When wanted as concrete, to form, independently of other materials, the foundation of some heavy structure, stony fragments of larger size are mingled with the lime than when the mortar is to be used to cement chiselled stones, or even than when wanted to constitute with rubble the interior of a wall. ”

“ It is clear that in this way each block or slab is made to provide the maximum of wall area at the expense of the thickness of the wall. Naturally, in districts where the rock is of a slabby nature blocks of a more or less uniform thickness lay ready to the builders' hand, and the appearance of the structure was much more finished than it would be in places where the rock had a less regular fracture or where shapeless boulders had to be relied on. ”

“ Many small houses in the country are built without any permanent foundation, but are temporarily supported on posts set in the ground, and “boarded down.” They are always shaky, and doubtful while they stand, and are frequently blown over altogether. As will be readily seen, the above method provides for the saving of one-half of the mason-work in the foundation. In many places stone is abundant, and will answer the same purpose as brick in this case, except for the 6 inches above ground. The laying up of a single-face wall, 21⁄2 feet high, of rough stone and mortar, would cost but a trifle. ”

“ And, although we are not hence to conclude that it is well to introduce courses of bad materials when we can get perfect material, I believe we may conclude with great certainty that it is better and easier to strengthen a wall necessarily of imperfect substance, as of brick, by introducing carefully laid courses of stone, than by adding to its thickness; and the first impression we receive from the unbroken aspect of a wall veil, unless it be of hewn stone throughout, is that it must be both thicker and weaker than it would have been, had it been properly coursed. ”

“ His third tier, if not his second, will probably appear a sufficiently secure foundation for finer work; for if the earth yield at all, it will probably yield pretty equally under the great mass of masonry now knit together over it. So he will prepare for the wall itself at once by sloping off the next tier of stones to the right diameter, as 56 at d. If there be any joints in this tier within the wall, he may perhaps, for further security, lay a binding stone across them, e, and then begin the work of the wall veil itself, whether in bricks or stones. ”

“ If both brick and mortar, or stone and mortar be porous, it becomes absorbed; if all are non-porous, it runs down until it finds a projection, and then drops off; but if the brick or stone is non-porous, and the mortar porous, the wet runs down the brick or stone until it arrives at the joint, and is then sucked inward. It being almost impossible to obtain materials quite waterproof, suitable for external walls, other means must be employed for keeping our homes dry and comfortable. Well built hollow walls are good. ”

“ The facings of the stones are all uniform, but most of them run back into the wall irregularly, acting in the same way as throughs in our dry-built walls at home in preserving the building from falling. ”

“ No matter what the character of the material to be excavated, the ditch clings closely to the Wall on all the lower ground. It is hewn through basalt, sandstone and limestone with equal indifference.
The Wall is constructed in the method usual with the Romans; that is to say, it consists of a rubble core mixed with mortar, faced on each side by masonry blocks. The stone used for the facing is a species of sandstone. The size of the blocks {27} is very regular: 8 or 9 inches by 10 or 11 inches on the face, and sometimes as much as 20 inches long. ”

“ This wall ran east and west, having a base measurement of 2·60 metres broad with its outer faces sloping—their ‘batter’ being 4 cms. in every rise of 25 cms. Its construction consists of two outer skins of small well-made limestone blocks built upon sandstone foundation slabs, with, in the middle, a core of stone and mortar rubble mixed with sand. In it was a doorway, about half-way along the length cleared, which opened out to the north—its door-jambs being on that side. The eastern extremity of the excavation then made, showed that in that direction it descended. ”

“ From the expense of carrying and working stone, the walls of buildings at a distance from a quarry, such for example as those in London, are seldom now built of solid stone, but a facing of this material is applied only on the external surface of the wall, which is built of brick. ”

“ South of the turnpike road, and behind a small house, called Beggar-bog, is a low freestone crag, which exhibits some quarry-like excavations, filled with the chippings of stone. It has probably furnished material for the Wall, the stone being of the same character.
The stream which we next cross is the Knag-burn; it forms the eastern boundary of Housesteads. Passing it, we scale the ramparts of this far-famed station. ”

“ With the dark mortar the joints will be visible, modifying the color of the wall, in some cases, perhaps, improving it; while the red will give a more uniform tint, on which not only colored brick or stone will appear to the best advantage, but the lines of the openings and other essential details are brought out in clearer relief. You would perhaps expect coloring the mortar the same shade as the brick to give precisely the effect of painting the entire wall. ”

“ Bricks cannot be too well burnt for garden walls; the harder they are the less moisture will they absorb. Many excellent walls are built of stone. The best is dark-coloured whinstone, because it absorbs very little moisture, or in Scotland Caithness pavement 4 in. thick. The stones can be cut (in the quarries) to any required length, and built in regular courses. Stone walls should always be built with thin courses for convenience of training over their surface. Concrete walls, properly coped and provided with a trellis, may in some places be cheapest, and they are very durable. ”

“ For ordinary dwelling-house work there should be at least one footing eight inches in depth, and six inches projection on each side of the wall. Stone walls for foundations are usually made not less than eighteen inches in thickness. It is not easy to lay a good stone wall less than eighteen inches in thickness. While the same number of cubic feet of stone work may cost less than brick work, a stone foundation ordinarily would cost more than one of brick for the reason that a brick wall does not have to be so thick. ”

“ The wall had a rough rubble foundation, then a course of plinth stones on the outside, with three tile courses corresponding to it on the inside of the wall, then followed five courses of the fairly square facing stones on both sides of the wall, then two rows of tile, five courses more stone and two rows of tile, then five more stone courses; above this level the wall had been destroyed. The stones and tiles were set in mortar, and the latter, except for the three courses at the bottom on the inside, which served as a plinth, were carried right through the thickness of the wall ”

“ The foundation (strictly speaking) is made of large blocks, roughly squared, and not rusticated, fastened together by a tenon left projecting from the face of one stone, fitting into a corresponding mortise in the next: there is not a trace of iron or lead or mortar; but where the wall rises above ground its face is vertical, the blocks are more carefully squared, and rustic work is used, with wide and deep grooves ”

“ More primitive still would be the single wall with a bank of retaining earth behind it for support (Fig. 2) , while more complicated would be one strengthened by a central core of masonry (Fig. 3) . Remains of these walls have been found in [Pg 19] various places still in situ. It is quite possible that a palisade of sharpened stakes or of wattle surmounted these stone walls, thus still further adding to their efficiency. In a "soft" country, where only earth or chalk is available, timber would naturally take the place of stone. ”