The Construction of the Small House / A Simple and Useful Source of Information of the Methods of Building Small American Homes, for Anyone Planning to Build

It will be remembered that the commonest types of small houses are the wooden frame house and the masonry-and-wood house. Now it is essential that certain definite qualities be required of all materials of construction which enter into the building of these houses, and although there are many facts covering the standard qualities and methods of manufacture, yet one cannot expect to remember all of them. It is sufficient if one knows those qualities which mean satisfactory building and durability when applied to the structure.

Of the large number of materials which enter into the construction of a house, the following are the most important and should be maintained at a high standard: wood, clay products, cementing materials, metals, glass, and paint.

WOODS

It is possible to enter into a long discussion of the classes, qualities, methods of conversion, defects of wood and similar subjects, but these are not pertinent to the main idea, namely, the essential qualities of woods which are used in the construction of the small house. There is a prevalent impression abroad that the supply of wood is becoming so depleted that it will in the future be used only for special ornamental features. This is wrong, for we still have enough virgin forests left to supply the country for several generations, and with the growth of forestry we will maintain a certain source of supply.

We have two classes of woods on the market which are used in different parts of the structure, according to their special qualities. These are commercially known as hard and soft woods, although this is not a very scientific distinction, since some of the soft woods are harder than some of the hard woods, and vice versa. Scientists have more accurate names than these, but as the above are so well established, there is no doubt as to what is meant.

In the market, lumber is not only classified according to the above, but according to the species of tree it comes from, and also according to certain standard grades of the same kind. These grades are determined by the presence of certain defects. The recognized defects are knots, shakes, checks, splits, streaks, pitch-pockets, stain, rot, wane, warp, cupping, mineral streaks, pith on the face of the board, and worm-holes.

Various large lumber associations issue rules governing standard sizes and classifications for woods to be used in construction. The best and the next best are the usual grades which are used for the interior and exterior trim of houses. These grades have many designations, as “clears” and “selects,” or “A” and “B,” or “No. 1” and “No. 2,” or “firsts” and “seconds.”

The grades used for the rough framing, such as studs, joists, rafters, subfloors, and sheathing, are not so good. They are designated as “No. 1 common” and “No. 2 common.” A poorer grade still, known as “No. 3 common,” is sometimes used for cheap temporary structures.

For the details of grading and standard sizes of lumber, one should possess Circular 64 of the United States Department of Agriculture on “How Lumber is Graded.”

Next to the grading of timber, the most important factor of quality is the relative durability of the various woods, for upon this depends to a large extent the choice of them for special places. The table on page 23 is taken from a government classification.

From this table it will be noticed that the soft woods as a class are relatively more durable than the hard woods. This is true, because of the fact that the structure of soft woods is simple, while that of the hard woods is complex. When the former become wet and expand and then dry out and shrink, the structure is not stressed internally as much as is that of the hard woods, and they are therefore much more capable of withstanding the action of the weather. Also certain of the soft woods have natural properties of resisting dry or wet rot.

Certain species of woods are, therefore, selected for particular parts of the house according to the needs of durability, strength, appearance, and local supply.

Rough wooden framing requires a wood that is fairly abundant and strong. The soft woods are generally used, and those which are classified as durable in the table are the most used.

For rough underflooring and sheathing the cheapest and most abundant local wood is used. Durability is not essential.

For shingles the most durable woods must be used, such as cypress, cedar, and redwood.

Lath are generally cut from waste slabs, and should be of some soft wood like spruce or of one of the softer hard woods. Siding should be made from one of the soft woods, especially those which are classed as durable in the table.

Porch columns and the like require very durable woods. They should be hollow except for very small ones. Built-up columns of interlocking type are usually specified, but the lumber used should be thoroughly kiln-dried so that the joints will not open.

Flooring should be capable of resisting wear and should not splinter. The hard woods as a class are more adaptable than the soft woods, although yellow pine and Douglas fir are used a great deal on account of their cheapness. These latter are divided into two grades: “flat grain,” in which the annual rings are almost parallel to the surface, and “edge grain,” in which the annual rings run almost perpendicular to the surface. The latter is more desirable, since it wears better. The flat grain splinters off, due to the layers of soft spring wood and hard summer wood. Oak flooring comes plain and quarter sawn, which is practically the same as the cut of yellow pine, but since oak is strong either way, the wearing qualities are not very different. Maple is also an excellent wood for flooring, since it is hard and smooth.

Door and window frames may be made from many kinds of wood, although the soft and more durable woods are generally accepted as the best. Specially hard and durable woods should be used for the thresholds.

Doors which are to be used on the exterior should be of a soft and durable wood. The choice of wood for interior doors is limited only by the taste of the designer. The doors which stand best the warping effect of steam-heat in the winter are constructed of white pine cores with a veneer on the exterior made from some hard wood.

Sash and blinds require a soft and durable wood. Sash are subject to the drying of steam-heat on the interior and cold and dampness on the exterior. Sash built of yellow pine sapwood have rotted in a few years, and while soft maple, birch, and basswood have been used, they are not durable, although easily worked. White pine is considered to be the best for sash and blinds.

The selection of woods for interior trim depends only upon the designer’s taste, since neither relative durability nor strength is a requirement. The harder woods in the past have been used more extensively for interior trim than the soft, because of their supposedly better and richer appearance, but this is not so true to-day, for new methods of treating such woods as cypress and yellow pine have shown them to be fitted for the best artistic places. Of course hard woods are not dented from knocks by furniture as easily as the soft woods, and in this way retain their appearance longer.

CLAY PRODUCTS

Bricks.—In considering the essential qualities of bricks for the small house it must be appreciated that those bricks which are used on the exterior must be able to resist the effects of weather and produce the best artistic results, while those which are in the interior of walls or chimney need not be held up to such rigid standards. The determination of the resistance of bricks to frost and weather action is quite simple. A brick which struck by a hammer gives a clear ring is one which has been well burned and has no soft spots, cracks, or weak places. Such a brick can be said to be satisfactory for exterior use, provided that it has the proper form and color desired and is not so overburned as to be twisted and warped. Another requirement sometimes specified is that the face brick made from soft clay should not show a percentage of absorption in excess of 15 per cent, and for the stiff-moulded or dry-pressed bricks not more than 10 per cent. This, however, cannot be a hard-and-fast rule, due to the variation of clays.

Certain red bricks, unless they are burned very hard, show, when built into the wall, a very ugly white surface discoloration, called “whitewash” or efflorescence. This is not entirely due to the brick, since the mortar that is used may sometimes produce it. If it is due to the brick it can be discovered before the brick is used in the wall, by placing a sample brick on edge in a pan containing one inch of either rain or distilled water. As the water is absorbed by the brick, the white discoloration will develop on the top surface after several days of standing if it contains the salts which will cause the whitewash. Those bricks which have been very hard-burned will not discolor under any circumstances. If after passing this test the brick wall should develop whitewash, it can be laid to the mortar. In order to prevent any such occurrence it is necessary to waterproof the joints around window-sills and between the foundations and the wall, so that the minimum amount of water will be soaked up into the wall when it rains. An expensive addition of 2 per cent of barium carbonate to the mortar will tend to fix the soluble salts which cause this efflorescence.

Hollow Tiles.—Hollow terra-cotta tiles covered with stucco or brick veneer are being used more extensively than ever, due to the cheaper cost of laying them, since they are larger units, and also to the fact that they build a cellular wall. Wherever these tiles are used for bearing walls it is important that they be hard-burned, but the softer ones may be permitted in non-bearing partitions. Tiles for use in outer walls should be hard-burned, free from cracks, straight, and should not show a greater absorption of water than 10 per cent. As these tiles are intended to support loads from floor-joists, it is essential that they should have the correct proportion of voids to solid shells and webs. The maximum width of any voids should not exceed 4 inches and the thickness of any shells or webs should not be less than 15 per cent of this measurement. In tests it has been shown that tiles laid with webs vertical are stronger than those with webs horizontal, but this difference in strength is not of very great importance in the small house, where the loads are very light. The chief thing to avoid in the setting of tile, when they are vertical webbed, is the dripping of mortar to the bottom and the insufficient spreading of it over the ends of the webs and shells. This can be overcome by laying wire lath over each course, and then buttering the mortar on the inside and outside edges. The mortar is prevented from falling out of place by the lath, and because it is not continuous through the wall, any penetration of moisture through it is stopped.

Cementing Materials

The most important cementing materials which enter into the construction of the small house are lime, cement, gypsum, and their various mixtures, as mortar, plaster, and concrete.

The various technical requirements for good lime and cement are very strict and detailed, and for the small house it is customary to cover their qualities in the briefest manner by referring to the standard specifications of the American Society for Testing Materials.

Slaked lime should be made from well-burned quicklime, free from ashes, clinker, and other foreign materials.

Dry hydrated lime should be the finely divided product resulting from mechanically slaking pure quicklime at the place of manufacture.

The specifications of the American Society for Testing Materials covering the quality of cement should be followed where large purchases are made. Where small quantities are to be used, the reliability of the dealer must be the basis of purchase.

As mortars and concretes made from these materials are as important as the cements or limes, it is essential to have definite standards for them.

Lime mortar should be made of 1 part by volume of slaked lime putty or dry hydrated lime and not more than 4 parts by volume of sand. The use of hydrated lime is recommended, since the poor qualities which are apt to develop from careless slaking of quicklime are thus avoided. It also comes in smaller packages, and if the entire quantity is not used at once it may be stored without deterioration. It is only necessary to mix the hydrated lime with water until it becomes a paste, and then add the necessary sand. The purpose of adding sand is to increase the bulk and to reduce the shrinkage which pure lime paste will develop as it hardens. Pure lime paste, without sand, will shrink, crack, and develop very little strength. By introducing sand this contraction is reduced, but the addition of too much will decrease the strength slightly. However, this decrease of strength is very little. A mortar made of 1 part lime to 6 parts sand is nearly as strong as one made from 1 part lime and 3 parts sand. The maximum amount of sand to be used is generally governed by the ease of working, and not so much by the strength. A lime which is too sandy will not spread easily on the trowel.

Cement mortar is, of course, a stronger material and can be used in damp places where lime mortar would deteriorate. The theory of mixtures of both cement mortar and concrete is to proportion the materials so that they produce the most compact substance. For instance, in the cement mortar the cement should just fill the voids between the particles of sand, and in concrete this cement mortar should just fill the voids in between the larger aggregate, and this larger aggregate should be so graded in size that it makes the most compact body. It used to be thought that certain definite numerical proportions, as laid down by theory, of the various ingredients would hold true for all kinds of sands and aggregates. For instance, the proportion of 1 part of cement, 3 parts of sand, and 6 parts of aggregate was thought to be the best for ordinary use under all conditions. But extensive tests by the government have shown that the only real way to determine the correct proportions of mixtures is to experiment with the particular sand and gravel that will be used, and to test them to see what ratios give the most compact mass. It has also been found that round aggregates, like pebbles, produce the strongest concrete, since the particles flow into place better than the sharper aggregates, which formerly were considered necessary because of the supposed idea that they made a better mechanical bond with one another. The proportion of water is also important, a quaking mixture producing the best results.

It is customary in small work, however, where no experiments can be made on various mixtures to determine their proper proportions, to follow the old rules of thumb for amounts.

Cement mortar should be made of cement and sand in the proportions of 1 part of cement and not more than 3 parts of sand by volume.

If cement-lime mortar is to be used it should not have more than 15 per cent by volume of the cement replaced by an equal volume of dry hydrated lime. The addition of hydrated lime to cement mortar improves its working qualities, making it slide more readily on the trowel and also increasing its waterproofness. Its strength is not decreased within the limits prescribed.

In concrete work it is as important to have good sand and aggregate as cement. Sand should be sharp, clean, coarse quartz. The sand used should not, when it is rubbed in the hand, leave the palm stained.

Gravel which is used as an aggregate should be free from clay or loam, except such as naturally adheres to the particles. If there is too much clay or loam, it should be washed with water. When bank gravel is used the best results will be obtained if it is screened from the sand and remixed in the proper proportions for fine and coarse aggregate. For ordinary mass concrete the size of aggregate should vary from ¼ inch to 2 inches, and in reinforced work should not exceed 1¼ inches.

The best proportion of parts to use must vary according to the requirements, but for the small house good results will be obtained by using 1 part of cement, 2 parts of sand, and 4 parts of gravel or broken stone.

Stucco Work.—Stucco is really a Portland-cement plaster used on the exterior, and its success depends a great deal upon the quality of materials employed and workmanship. All stucco to a greater or less degree cracks, but the problem is to make the cracks as small as possible. The government is carrying on an extensive investigation of the problem of stucco through experiments on fifty-six exterior panels which have been under observation since 1915. Each one of these panels has been spread upon a different base or made with different proportions. So far only two panels have been found to be entirely free from cracks, although many are practically uninjured by the small cracks which have developed. It is therefore quite evident that as a rule it must be assumed that the stucco will crack to a certain extent, and in order to cover such defects a rough surface is the best. As to proportions of mixtures, there is a great variation of opinion. The commonest is 1 part of cement, 2½ parts of sand, to which is added about ¹/₁₀ part of hydrated lime by weight of cement. For a more detailed account on stucco, send for the Progress Report issued by the Bureau of Standards on the Durability of Stucco and Plaster Construction.

Plastering.—The qualities of internal plaster depend upon the construction of the wall, the methods of application of the plaster, and the quality of the plastering material.

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.

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.