Part 3

The walls and ceiling to which plaster is to be applied must be so constructed as to be practically rigid under the loads that they will carry. Since plaster is not elastic, any slight change in shape of the surface will cause it to crack. The common backings which are satisfactory for plastering are wood lath, metal lath, and masonry, such as concrete, terra-cotta tile, brick, plaster board, etc. Wood lath makes the least rigid back of all, and for this reason is not considered the best, although it is the cheapest. Unless the wood laths are wet before the plaster is applied, they will absorb the moisture from the plaster and swell, thus cracking the wall. Metal lath for this reason is superior. Masonry walls should be made rough to give the necessary key for the plaster to cling to. In brick walls the joints are raked out, in concrete walls the surface is picked, and the outside of terra-cotta tile is marked with grooves for this purpose.

The best results in plaster are secured with three coats. The first coat is called the scratch coat, and is intended to form a bond between the wall itself and the plaster. It should be pressed into the apertures between the lath to secure a good bonding key, and its surface should be scratched with a tool to give the required bond between it and the next coat, or brown coat. The brown coat forms the main body of the plaster and averages about ¾ inch to ⅞ inch thick. The finished coat is then added on top of this and is intended to develop a plane surface with the desired color. Each coat should be allowed to dry out and then be wet before the next one is added. If wood lath is used, this drying and wetting will cause the lath to shrink and swell, so that cracks will be developed in the scratch and brown coats. These should be filled in before the finished coat is added.

The materials which should be used in the various coats depend upon the requirements which are necessary for each one. As the most important characteristic of the scratch coat is strength, and that of the brown plasticity, and the final coat appearance, the materials must be proportioned accordingly.

SCRATCH-COAT PROPORTIONS Hydrated lime 133 parts by weight Sand 400 “ “ Hair 1 part “

BROWN COAT Hydrated lime 100 parts “ Sand 400 “ “ Hair ½ part “

FINISHED COAT _Smooth Finish_ 1 part by volume of calcined gypsum. 3 parts “ lime paste.

_Metals_

The most used metal in the small house is the so-called tin-plate or roofing tin. It is not a true tin-plate, for it contains 75 per cent lead and 25 per cent tin, applied to a base of soft steel or wrought iron. It comes in two grades, IX and IC, the former being No. 28 gauge and the latter No. 30 gauge. The lighter is used for roofing and the heavier for valleys and gutters. The tin does not entirely protect the base metal, so that it is necessary to paint both sides before it is applied.

Galvanized iron is another form of sheet metal which is extensively used for work on the small house. It consists of sheet iron or steel, covered with zinc. This coating should be free from pinholes or bare spots, and of a thickness to prevent cracking or peeling. If the coating is sufficient and well done, it is superior in lasting quality to the ordinary tin-plate.

Copper, since the war, has come back into use again as a sheet metal for the small house, for its cost has dropped within reason. In order to meet a certain popular demand a light grade of copper sheet roofing has been placed on the market, although it has generally been considered that sheets weighing less than 16 ounces per square foot were not suitable for roofs.

_Glass_

There are two kinds of window-glass used, double thick and single thick. The former is ⅛ inch thick or less, and the latter is ¹/₁₂ inch thick. It is customary to use double thick in all window-panes over 24 inches in size. The grading is AA, A, and B, according to the presence of defects, such as blisters, sulphur stains, smoke stains, and stringy marks.

Plate glass is used only where the expense will permit. It is different from window-glass in that the latter is made from blown glass, while plate glass is made from grinding and polishing down sheets of rolled glass.

There are quite a number of other minor materials which enter into the construction of the small house, but they are more or less identified with the mechanical equipment and the finishing, and will be considered under these headings.

Sheet lead weighing 5 to 6 pounds per square foot is often used for counter-flashing. Leaders and leader heads of cast lead have been made practical by one company, which has developed a method of hardening the lead.

Zinc, like copper, is again being urged upon the public by the manufacturers since the war demand is over. Zinc spouts are usually made from No. 11 zinc gauge, which is equal in thickness to No. 24 steel gauge.

There is hardly any need to mention the durable qualities of copper, zinc, or lead. Wherever the cost permits, one cannot deny that materials of such durable nature are the proper ones to use.

IV TYPES OF WOODEN-FRAME CONSTRUCTION

_Types Explained_

There are no sharp distinctions between the various types of wooden frame construction. But in order to classify certain tendencies, we will arbitrarily define four types. To these we will give the names of braced-frame, balloon-frame, combination-frame, and platform-frame.

The braced-frame is the oldest type, and originated in Colonial days in New England. It was developed under the influence of a tradition of heavy, European half-timber construction, and also nourished by the abundance of wood directly at hand. The fact that nails were not made, except by hand, urged the carpenters to use methods of fastening which required as few as possible. Because of these factors, then, certain definite characteristics of this type of wooden frame construction manifest themselves in the use of timbers, far larger than necessary for safety, and joints consisting of mortises and tenons.

As the sawmill became mechanically more rapid, and as nails were being turned out by machines more plentifully, the Yankee who went West on adventuresome trips, and cared little for a permanent dwelling, devised a system of light-frame construction which became known as the balloon-frame. This was put together with the greatest speed, and required only nails for fastening all joints. The timbers which were used were standardized to one size, namely, 2 inches by 4 inches.

Now, both of these types had advantages and disadvantages which were bound to influence later builders. Those who had been accustomed to build according to the braced-frame system found that lumber was becoming scarcer, and that nails were cheaper than they formerly were. Certain features of the balloon-frame appealed to them, such as its greater speed of construction, its smaller timbers, and lightness. On the other hand, those people who had lived in houses constructed according to the balloon system of framing found that they were very flimsy, that fires quickly consumed them, that rats and vermin could travel freely through the walls, and that, after all, they were only the most temporary sort of shelter. These folks looked back at the old methods of building, and saw the good features of solidity and permanence. We had, therefore, the growing together of the two systems of construction into a type which we call the combination-frame dwelling.

However, progress did not stop at this point. The houses built according to this newly devised system were found to settle unevenly, which cracked plaster ceilings and walls and made doors and windows into leaning parallelograms. The cause of this was found to be due to the natural shrinkage of wood as it dried out. Now, all wood shrinks mostly across the grain, and not with it, so that the amount of settlement of any wooden wall depends upon the amount of cross-section of wood which it contains. If there is more in the interior partitions than in the exterior, it is certain that the floor-joists will settle down on the inside ends more than the outside. This is exactly what happened. It occurred not only in the combination-frame but in the braced and balloon frame. Various devices were introduced to avoid this defect, but all were more or less incomplete. Nevertheless, it all led gradually to the development of the fourth type of construction, which is called the platform-frame, for lack of a better name. This frame solves the problem of uneven settlement in the wooden structure. It also makes the location of the windows of the second floor independent of those of the first floor, which is not the case with the balloon-frame, for in this type the studs extend in one piece from the sill to the plate, requiring the centring of the windows of the second floor over those on the first.

The methods which are used in constructing the small house of to-day are not as simply classified as the previous description would lead one to believe. The old New England braced-frame has practically gone out of existence, yet many of its features remain. The balloon-frame is used only in the cheapest sort of structures, yet many of its details are found in the modern dwelling; The combination-frame in all its many varied forms can be called the advanced type.

_Study of Detail in the Combination-Frame_

The illustrations show the four types in their entirety. But in order to fully understand the combination-frame, it is necessary to know what features of the braced-frame and balloon-frame are used to-day.

THE FEATURES OF THE BRACED-FRAME WHICH HAVE SURVIVED

1. _The use of the girt_, because it permits the location of the second-floor windows at any point irrespective of the first floor windows. This cannot be done when a ribbon-board is used, for this requires studs which extend continuously from sill to plate, and if any windows are to be located on the second floor, they must be placed directly over those on the first floor. The ribbon-board does not act as a stop for either vermin or fire, as does the girt. However, fire-stops can be introduced in connection with the ribbon-board, if the extra expense is no hindrance.

2. _The use of the sill_, because it serves as a firm foundation for the outside studs and first tier of floor-joists. The balloon-frame has no sill, for the floor-joists are set directly upon the top of the foundation-wall, and the exterior studs are built on top of them.

3. _The use of the corner braces_, because they stiffen the frame.

FEATURES OF THE BALLOON-FRAME WHICH HAVE PERSISTED

1. _The use of small timbers_, or the standardization of the 2 by 4 for all parts except the sill, because of economy. The corner-posts are made of three 2 by 4’s, and the plate is made of two 2 by 4’s.

2. _The use of the nailed joint_, because of its cheapness and its greater strength. It will not rattle loose when the timber seasons, as does the mortise and tenon joint in the braced-frame.

3. _The use of the ribbon-board_, in place of the girt, for those houses which are to be stuccoed, and a rigid, outside wall-frame is desired from sill to plate.

4. _The use of diagonal sheathing-boards_, to brace the frame instead of the corner-pieces. The reasons for this are not very certain, since diagonal bracing with sheathing is not always effective, while it is extremely wasteful.

The combination-frame includes all of the present-day methods which make use of selected features of both the braced-frame and balloon-frame, such as were noted above. There are no rules to follow. In certain sections of the country one type is favored more than the other. Where a house is to be covered with stucco, the balloon-frame is a better type to use than the braced-frame, since it gives a stiffer outside wall as a backing for the stucco.

_Platform-Frame_

It will be noticed in the illustration how different is the amount of cross-section of wood in exterior and interior walls of the combination-frame, a thing which causes the unequal settlement previously alluded to. In order to reduce this to a minimum, it is often specified that the studs of all interior partitions be carried down to the top of the cap of the partition below or to the top of the supporting girder, thus reducing the amount of cross-section timber. This is not a complete cure, however, although it is a big improvement.

The real solution of the difficulty lies in the use of the platform system of construction. In this system the first floor is built on top of the foundation-walls, as though it were a platform. A sill, called the box-sill, is constructed for the exterior support of the ends of the floor-joists by laying down a timber the same size as the joists and setting another one on the extreme edge in a vertical position. The angle thus formed makes a resting-box into which the floor-joist can be framed. The interior ends of the floor-joists should be supported upon a steel I-beam upon which has been placed a 2-inch-thick timber. The I-beam should be supported upon steel-tube columns which have been filled with concrete. On top of the floor-joists should be nailed the underflooring, laid diagonally. The first floor then appears as a perfectly smooth platform. Now wherever there is to be erected an interior or exterior partition, a 2 by 4, called the sole piece, is nailed directly on top of the rough flooring. This serves as a sill for the studs of the partition, which are now erected vertically upon them and capped with double 2 by 4’s on the top. Now the second floor is built on top of the partitions in the same manner as the first, and a new platform is constructed, so to speak. Upon this is then erected the partitions of the second floor, and on this the floor of the attic. In fact, this construction proceeds floor by floor, and each floor is an independent platform. If the drawings are examined it will be noticed that the amount of cross-section of wood in any one bearing partition is identically the same as in any other. The dwelling built in this way, then, cannot settle unevenly, and the cracked plaster and twisted doors will be eliminated.

_Features Common to All_

There are certain features which are common to all types of frames. For instance, the framing around all doors and windows requires the use of double 2 by 4’s or the use of one 4 by 4.

These framing studs around the window are set 5 inches higher and 8 inches wider than the dimensions of the finished window. Those about the door-openings are set 2 inches higher and 4 inches wider.

All use sheathing-boards of ⅞-inch stock to cover the outside of the studs, and these are usually 6 inches to 8 inches wide.

The usual spacing of studs is 16 inches on centres, and they are generally of 2 by 4’s, although where any pipes or flues are run through the partition they should be 2 by 6’s.

Interior stud partitions should be bridged or braced once in their height, and partitions which run parallel to the floor-joists should have a capping-board, so that the proper nailing for lath can be secured. In fact, at all intersections of partitions care should be exercised that the required nailing for lath is provided.

In the construction of roofs the average spacing of rafters is 20 inches on centres. They should be doubled around all openings. The ridge is usually of a 1-inch by 10-inch piece. The size of the rafters varies with the length of span and load. They are usually 2 inches by 6 inches for short spans and light loads, and 2 inches by 8 inches or 2 inches by 10 inches for long spans and comparatively heavy loads. Valley rafters must always be deeper and heavier than the rafters and should be designed as a girder. The hip rafters do not carry any great load, but are often made deeper to fit the incline cut of the jack rafters.

All floor-joists are spaced 16 inches on centres, and should be bridged. The following is the table commonly followed for good house construction, although lighter work is most often specified:

SPAN TIMBER

12' and under 2" × 10" cross-bridged once.

12' to 15' 2" × 10" doubled every other one, if good stiffness is desired, and bridged twice.

15' to 20' 3" × 12" and of long-leaf yellow pine, crowned at centre ½", and bridged three times.

20' to 25' 3" × 14" of long-leaf yellow pine, crowned at the centre 1" for the 25' spans, and bridged four times.

Floor-joists should be doubled around all openings larger than 3 feet, and joists should be hung from the header beam by metal straps.

There are many precautions which should be taken to prevent the spread of fire in the wooden frame house, but those will be considered as a special subject. Likewise the discussion of certain defects of construction which are commonly found in the speculative house will be dealt with later.

V CONSTRUCTION OF THE MASONRY AND WOOD DWELLING

In one of the previous chapters it was pointed out that the type of construction next in general use to that of the wooden frame house was the dwelling of masonry and wood. This was designated as Type II, and defined as a building with exterior walls of stone, brick, concrete, or terra-cotta, and interior floors and partitions of wooden frame construction.

The difference in construction between the wooden frame structure and the masonry-and-wood building is mostly in the material used for the exterior walls. The interiors of both types are constructed in practically the same way, the floors being of light wooden joists and the partitions of wooden studs.

The oldest varieties of the masonry houses in America are represented by the stone and brick dwellings of Colonial days. These are so substantially built, and often so artistic in conception, that they have become common models from which to draw inspiration. The concrete house of the monolithic or block type, and that of hollow terra-cotta tile, is a modern development.

_The Stone House_

The stone house is very adaptable to all those regions where this material can be secured from the excavation of the cellar or from some neighboring road improvement. Sometimes an old stone wall serves as a source of supply. Because of the native character of this material it will always be in harmony with the landscape.

In building the wall of stone there are a number of things to be observed, where success is desired. The wall should be well bonded together, the lintels over the windows should be strong, the foundations should be adequate to prevent cracks, the method of laying should be artistic, and the form of jointing in harmony with it.

All native stones used for rubble wall construction have certain characteristics of color and formation. Certain stones will split easily into long, flat shapes, others seem to have very little lamination and break into jagged, irregular patterns, while others are so soft that they lend themselves to easy shaping in squared blocks of regular size. Sometimes, even, the neighborhood may be filled with round field stones, which can be used to imbed into the face of the wall and produce a surface of round bumps. Whatever is the character of the native stone, it should be used in its simplest form and not forced into imitation of some other type. The soft brown sandstones which are seen in some Colonial houses are easily cut and squared; but to cut up a hard stone into such carefully shaped blocks, in imitation of this Colonial work, would not only be a waste of money but a waste of artistic effect.

METHOD OF LAYING

According to the way in which the stone naturally lends itself, we have various types of rubble walls. The commonest is the rough rubble wall in which the stones have neither regular shapes nor regular sizes, or even courses. The wall is composed of large stones and small stones (the latter are called spalls, and fill in the interstices between the larger stones). The joints of mortar between the stones may be plastered roughly over the surface, covering much of the face of the stones themselves, or they may be roughly but neatly pointed with white mortar, or the joints may be raked out. Where the stone has a natural tendency to cleave into long, flat shapes, the rough rubble may become more regularly coursed in appearance. All of these types are respectively illustrated in Figures 1, 2, 3, and 4.

A softer stone, which can be dressed with the hammer, may be treated in two different ways: It may be shaped to fit closely, without using any spalls to fill up the interstices, and, thus, appear as a cut-out puzzle; this is called “cobweb rubble.” However, the more dignified treatment is the squared, uncoursed rubble, in which the blocks are cut to rectangular shape and the joints pointed with a tool. Figures 5 and 6 illustrate these.

A wall built entirely of field stone depends upon the mortar for its strength. It appears the best when the joints of the surface are raked out, permitting a large part of the stones to project outward. Figure 7 illustrates this kind of rubble wall.

When the rubble wall is built with very carefully squared stones, and in regular courses, it partakes more of the monumental character of ashlar work and draws away from the rustic value of rubble. In determining the amount of cutting which is to be done, the character of the building should be considered, remembering that the smoother and more finished the wall, the more monumental is its appearance.

MORTAR, BOND, AND THICKNESS

The kind of mortar which should be used for the rubble wall depends upon its location and desired appearance. All foundation-walls, and all walls which are subject to dampness, should be built with Portland-cement mortar. Lime mortar may be used in walls above grade, although cement mortar, or cement-lime mortar is superior. As the strength of a rubble wall depends more upon the mortar than the bond, it is well to use the best. However, care should be taken that the wall is well bonded. A wall which consists of two faces, not bonded together, should not be built. A bond stone which carries through from one face to the other should be set into the wall every 2 feet in height, and every 3 feet in length. This bond stone should be flat and about 12 inches in width and 8 inches thick. The usual thickness of walls for dwellings not over three stories in height is 16 inches, and the foundation-walls are made 8 inches thicker than the wall above or 2 feet.

The footings under a stone wall should be of concrete, not less than 12 inches thick, and should rest upon solid ground at a depth equal to, or greater than, the frost-line below the surface, unless solid rock occurs above this point. The width of the footings should be such that it projects outward on both sides of the wall at least 4½ inches.

FURRING