FIGURE 24.-Termite shelter tube on inside face of concrete foundation wall. Wood sheathing used as outer form work was left in the ground when the concrete was poured, and so was a wood "spreader in the wall. Termites came through the sheathing, tunneled through the concrete wall along the spreader, and then built their shelter tube to the wood joists

Examine all joists that have had holes punched in them for piping. Holes less than 3 inches in diameter, if on the center line, have little weakening effect. Similar holes near the flanges, however, may be dangerous.

Unless the ceiling is plastered, the concrete slab will be visible between the steel beams. The concrete should be smooth and fit snugly against the beams at all points. Good concrete work is of vital importance in such floor systems.

Inside the Walls.

Figure 25 shows several methods used by builders in framing the sills and studs of a house. This framework is exposed only between the top of the basement wall and the first floor, where the basement is not plastered, or sometimes in the attic. The success of any framing is dependent primarily upon the use of thoroughly seasoned, dry lumber which will not shrink appreciably after it is in place. Green lumber will shrink across the grain, but not lengthwise. This means that studs and other lumber used on end will not change in length after the building dries out. Floor beams, however, and sills, flooring, and other horizontal lumber, if green or unseasoned, may shrink as much as 3 or 4 per cent 10 of their width or thickness.

Evidence of the use of unseasoned lumber in the construction of a house will be plaster cracks, gaps between the bottom of the baseboard and the finished floor, uneven floors, creaking stairs, sticking doors and windows, and the opening of mitered joints. Large vertical cracks in plaster over doors and windows, or in the center of wall spaces, are evidence of sagging in the framework of door and window heads, or of settlement in the foundations.

Let us examine Figure 26 showing the western frame, also called the platform type. Begin at the foundation wall and add up the horizontal lumber in the outside wall. Here is what we get:

If this 40 inches of horizontal lumber shrinks 4 per cent, it will shrink 111⁄2 inches.

The use of dry lumber which has already undergone its chief shrinkage will avoid most of this trouble. Proper framing minimizes the amount of horizontal or flat lumber. It also equalizes this amount in the outside walls and in the interior partitions, so that if any shrinkage does occur, it will be the same all over and thus avoid uneven settlement.11

10 See Bulletin 174, The Air-Seasoning of Wood, by J. S. Mathewson, Forest Products Laboratory, U. S. Department of Agriculture.

The western framing equalizes the amount of horizontal lumber in the interior and exterior walls, but does so by increasing this amount to about 38 or 40 inches, thus increasing the chance for unequal shrinkage in the walls. Moreover, in this type of framing the floors are not tied together as they are either with the continuous Studs of the balloon framing or where the studs are spiked against the sides of the joists as in the braced framing. Note also that the horizontal lumber is practically equalized in the balloon frame and that it only amounts to about 15 inches. With stucco, balloon framing is recommended, as a result of the tests conducted several years ago at the Bureau of Standards.

Getting back to our inspection, you are interested in what effect the use of green lumber has on the house. In an old house you will see this when you examine the walls, the levels of the floors, and the woodwork. In a new house (less than a year old), however, it will be too early for the evil effects of green lumber (if it has been used) to have made themselves apparent. In such cases your reliance that properly seasoned material has been used must be based on the reputation of the builder or the architect. Certain lumber manufacturers who grade-mark their products include a guaranty that their lumber is dried below a definite moisture content 12—another assurance if you can see the grade-mark stamp.

You may be able to see near the basement ceiling and in the attic the rough boarding or sheathing which, in the wood-framed house, is nailed to the outside of the studs. In certain sections of the country insulating boards are employed as sheathing. Since these boards vary in quality, thickness, efficiency, and strength, the product of each manufacturer must be given separate consideration. Lumber sheathing should be nailed on diagonally 13 unless the house is stuccoed, in which case horizontal sheathing has been found much better,1 diagonal bracing, however, must then be used at all corners of the house, to provide against high-wind pressures. Heavy building paper should always be used between the sheathing and the outside wall covering; it will render yeoman service in shutting out the wind, although its value as an insulator is negligible.

Fire Stops.

Spaces between studs or openings for pipes should be blocked off or "fire stopped" at all floor levels, but especially at the first floor. Even a 1-inch board helps some (which is one reason for extending the subflooring to the outside face of the studs), but incombustible filling is better. It should completely occupy the hollow space between floor joists and studs to a height of 3 inches above the floor level. Loose material should be held in place with a rust-resistant wire mesh, or wood strips at least 2 inches thick. Without fire stops these spaces may act as veritable flues in case of fire. Unblocked spaces permit warm air in the cellar to pass up to the top of the house and escape, thus increasing your bill for fuel. They also permit the passage of rats and mice from the basement to the upper part of the house. The speculative house seldom has any special fire stops, but if you ever build a house insist upon them. They are cheap insurance.

It is good practice and a wise precaution also to have the entire basement ceiling, or at least the area over the heating plant protected with metal lath and plaster or other fire-resistant material. There should be at least 15 inches overhead clearance. This applies also to wood framing at the sides of the furnace or boiler.

Test the various basement windows-see if they are securely hinged-have hardware that works and are not broken or warped

12 Moisture content is the ratio between the weight of water in a piece of wood and the weight of the wood when oven dried. The specifications for association grade-marked southern yellow pine provide for air-dried and also kiln-dried lumber.

1 Tests recently completed at the Forest Products Laboratory (Madison, Wis.) show walls with diagonal sheathing to be from four to eight times as strong as ordinary hori zontal sheathing.

14 Tests by U. S. Bureau of Standards.