(e) Lower and set in proper position. As in the previous jobs, wooden wedges are used on the face of the bed. 4. Placing anchors. If anchors are used set in place. The anchors furnished for this cornice are properly shaped to fit the anchor slot or hole cut in the stone. These are set in the stone and the ends bedded into the back wall. 5. Setting intermediate stone. 6. Setting top course. The preparation of the bed, the setting of corner stones, and the filling in with the intermediate stones in the top course of the twopiece corners follows practically the same operations as listed in the previous lessons. 7. Parging and backing up. 8. C'alking and grouting. Calk vertical joints and fill with mortar. Follow the suggestions regarding the calking of the joint and filling with grouting mixture as described in the previous lesson. 9. Pointing up. Remove calking and point up. As soon as the grout has hardened sufficiently, the oakum or manila yarn is removed from the joints and the opening pointed up with mortar. CAUTIONS 1. In order that the mortar on the outer edge of the cornice is not forced out, see that the necessary wooden wedges are inserted on the mortar bed. 2. See that the type of lifting device employed for hoisting and handling of stone is one that will not interfere with the setting and bedding of the blocks. 3. Where props are necessary under cornice pieces having considerable projections, see that these props are put in place securely and not removed until the stone has been properly backed. QUESTIONS 1. Why is the grouting of vertical joints in water table and projecting cornices preferable to slushing them with mortar? 2. Why are anchors required for cornices? 3. How should anchors be placed in the stone? Technical information sheet JOBS No. 9-11 Block-BL-III: Jobs calling for the setting of (architectural terra-cotta and) cut-stone trim. Job specification 6-A: Setting, anchoring, and joining several pieces of cut-stone trim having plain or molded faces and cut with or without slight overhanging projections. Type jobs a, b, c: Technical information relating to the setting and anchoring of plain band or molded belt courses and one or twopiece cornice or water table. PRELIMINARY Belt or water table cornices that serve as intakes to cap off the outer part of a wall at the point where it is reduced in thickness, serve two purposes-one, structural, and the other, ornamental. From a structural point of view, stone courses protect the work below by carrying off the water from rain and melting snow that falls upon the ledges. Because stone courses are employed for such purposes, it is of the greatest importance that the vertical joints between the stones be filled with good, dense mortar and made water tight. The other function of these cornices is to furnish an ornamental band pleasing to the eye and properly finishing a masonry wall at a particular point. The way in which these members are molded and the size of projection or intake, as the case may be, are based on the architectural style of the building and made to harmonize with the general treatment of the design. A plain band or belt course, on the other hand, is used only for ornamental purposes, either to break up a too high expanse of brickwork by using a horizontal banding of stone of contrasting color to the brick or to tie in a row of window sills or lintels by forming a continuous band of stone around the building, thus overcoming what otherwise might give a restless or uninteresting appearance to the wall surface. The way in which such band courses serve to tie the openings of the building together and thus make the exterior more pleasing will at once be evident if you will study a building in which belt or band courses have been used and compare it with the wall of some factory building in which there are a series of plain window sills and lintels, used merely for structural purposes. 1. Sizes of stone used in band courses and cornices. While the stone trim that bricklayers are called upon to set is more often detailed and cut in sizes which can be handled by a bricklayer and his helper with the aid of such tools as rollers and pinch bars, there are instances, especially in connection with the setting of stone cornices and entrance features of the larger type, where some larger lifting device is necessary. Whenever the pieces of stone are large, it is much better to lift them by some suitable hoisting device direct from the truck on which they are delivered to the building to their position on the wall rather than to attempt to handle such stone by rolling them over the floor onto the hoists in order to get them to their proper places. It is recognized that where stones are of this size and where there is a considerable amount to set a stone setter will be employed to take care of this part of the job. However, it is important that the bricklayer who may be called upon to set stone of this kind should know how to rig up simple hoisting devices such as are generally used for this purpose. 2. Hoisting devices. The type of hoisting device customarily used for lifting stones on buildings that are not more than two or three stories in height are known to the trade as "gin poles" or "breast derricks." In the larger buildings of fireproof construction, having the floors carried by a skeleton steel frame built in advance of the erection of the inclosing walls, a small, stiff-legged derrick may be used. (a) Gin pole. The lifting device known as a gin pole consists merely of a pole held in position by guy lines. At the top a block and tackle is attached for hoisting the stone, this being done by some form of winch. (b) Breast derrick. This consists of two upright supports latticed together in the form of a ladder with a winch placed at the bottom. The derrick is leaned either against a wall or supported by guy wires or ropes and is usually operated by hand. 3. Methods of picking up stone. There are various ways of picking up stone and attaching it to the block and tackle of a derrick for hoisting into position. The simplest method is by use of slings made of manila rope or rubberfabric belting. If this method is used, however, it necessitates setting the stone first on cleats, which have to be removed after the sling or rope has been loosened from the stone. Another method is by lifting the stone with "dogs" attached to the derrick sling. This method can be used only where vertical joints occur in both ends of the stone. The preferred method of lifting stone is by inserting some form of a lifting Lewis in the top bed, or by the use of a grabhook where the stone is of a size and shape that permits using this type of a device with safety. There are a number of different types of Lewises. The type which is generally used for lifting a stone which occurs in the horizontal course of the cornice or, in fact, for any stone in which the length is proportionately greater than the width and thickness, is the pin Lewis. This consists of two pins from five-eighths to 1 inch in diameter, having rings attached in the ends and carried by means of a rope sling. These pins are inserted in holes drilled diagonally toward the center near each end and on the top bed of stones. A somewhat similar pin Lewis, in which the two pins are carried by a ring instead of a rope, is used for lifting smaller, square-shaped blocks. There are also several types of single-hole knuckle or spring-type Lewises. Heavy stone of most any shape are handled by a large knuckle Lewis made up of three or five pieces carefully fitted in a beveled hole and bolted together. The steel grabhook customarily used in holding the stone is in appearance similar to a larger pair of ice tongs, having a block of wood surfaced with lead over the point which is placed on the face of the stone. On the back of the stone a small depression is chiseled to receive the point of the tongs. The tongs are a lifting device that is not considered practicable in handling heavy cornice members. The lifting Lewis is, however, the most satisfactory device from the standpoint of the bricklayer or stone setter because this allows him to drop the stone on the mortar bed in exact position. Bricklayers should be familiar with these different types of lifting devices in order to judge which one to select for the various sizes and shapes of stone which they are called upon to set. 4. Anchoring. In all cases where the projecting part of the belt course, cornice, or other projecting piece of stone approaches in volume that part of the stone which occurs back of the face line of wall, thus bringing the center of gravity close to the face, it is advisable that such stone be anchored back into the brickwork or down into the wall, so there will be no danger of overturning. Where it happens that the thickness of the brickwork of the stone is insufficient to provide anchorage to the wall, provision is made to anchor such stone by long bolts in the brickwork underneath the stone for the attachment of anchors which will secure the back of the stone down on the wall. The anchors are usually made of by 1 inch or 14 by 14 inch flat steel. One end of these anchors is hooked down into the stone about 1 inch. The other is hooked down, or up, as the case may be, into the brick backing. These iron or steel anchors should always be galvanized or covered with a heavy coat of asphaltum to prevent rusting. 5. Mortar. For setting heavy stones, the mortar is usually mixed somewhat stiffer than is customarily used for setting smaller cut stone, so there will not be any appreciable settling of the stone and forcing out of the mortar after it has been tamped into position in its bed. For that reason, it is very important that the surfaces of large stone that are to be set in the bed be thoroughly wet first, on account of the large expanse of surface and the consequent capacity of such a stone for absorbing water from the mortar, thus preventing the mortar from having time for setting and attaining its proper strength. 6. Protecting stone courses. Care should be exercised to prevent mortar from dropping or splashing on stonework which has been set. This mortar, if not removed immediately, will tend to bleach the stone, leaving a lighter surface, thus defacing the appearance of the work even after it has been cleaned off. These spots will show until such time as the stonework has had a chance to weather back to its natural color. It is therefore customary, as suggested in the job outline sheets, to provide protection either with building paper, boards, or both. Where boards are used for protecting stonework, they should be either of white pine or spruce, as such woods as yellow pine or similar resinous woods are apt to cause bad stains on the stone. Strips of zinc built into the wall are usually used to hold these boards in place. The boards should be fastened to these strips with galvanized nails, as ordinary nails will rust and cause stain streaks on the stonework. 7. The difference between anchoring cut stone and terra cotta. At this point it will be well for the bricklayer to keep in mind that there is a different principle involved in securing cut stone to the backing than that of fastening terra cotta. Terra cotta quite frequently is anchored to steel supports above, and may otherwise be hung or suspended from anchors, whereas stone in the ordinary run of work should invariably be anchored down into the masonry below or be supported by steel members placed underneath it. There are comparatively few instances where it is advisable to hang the stone from steelwork placed above it. 8. Laying out stone previous to setting. While not customarily done on the job, it is very often advisable to assemble the features of a stone course on the floor in their approximate positions in order to see if the various members fit. This is particularly important where enriched moldings or carvings extending over two or more pieces of stone are to be set. II. REFERENCES You are referred to the chapters on drawing and science in Section Job outline sheet JOB NO. 12 Block-BL-III: Jobs calling for the setting of (architectural terra-cotta and) cut-stone trim. Job specification 7: Setting cut-stone quoins, window jambs, and head in a brick constructed building. Type job a: Setting cut-stone quoins in corner of brick building. |