This section is from the book "Cyclopedia Of Architecture, Carpentry, And Building", by James C. et al. Also available from Amazon: Cyclopedia Of Architecture, Carpentry And Building.
Close attention must be given the stairs to secure a satisfactory result. In the beginning the stringers must be examined to see if they correspond to the plans in the number of steps, and that ample head-room is provided where one flight of stairs comes over another. The plans will show the number but not the height of the risers, as this can only be determined by dividing the whole height from top to top of floors, by the number of risers shown. This should have been laid out to give for ordinary stairs a rise of about seven and one-half inches, and the sum of the tread and rise together should make for an ordinary house staircase between seventeen and seventeen and one-half inches, so that with seven and one-half inches for the rise, the tread should be nine and one-half or ten inches. Another rule is that the product of the rise and tread should be seventy to seventy-five inches, that is, if the rise is six inches, the tread should be eleven and two-thirds to twelve and one-half inches. For stairways where the space is limited "winders" may be inserted (Fig. 73), but where there is ample room, it is well to avoid them.
The question of head-room is an important matter and one that is not easily foreseen, so that often costly stairways which are otherwise well conceived are sometimes spoiled by too close head-room. With floors of the thickness of ordinary dwellings the well-room should extend over at least thirteen risers, and where one flight comes directly over another, seven and one-half feet in the clear, over the face of the riser, should be allowed.
In the construction of stairs methods differ somewhat. In New England it is customary to build the finished work of the stairs upon the rough stringer, piece by piece. The treads and risers are brought from the shop all fitted and are nailed into place, the risers are first put on, grooved at the bottom to receive the tongue of the tread, and the tread grooved on the under side and fitted over a tongue in the riser. (Fig. 74.) A small moulding is then put in the angle under the edge of the tread, and this finish is carried around the end of the step in "open string" flights, where the tread appears at the end. (Fig. 75.) The inside or wall edges of both tread and riser are grooved on the line of the base, the lower edge of which is scribed to the outline of the steps and cut away on the hack to form a tongue, which, after the steps are all in place, is driven into the grooves, the stair nosing being cut away. This is necessary to prevent the appearance of a crack along the whole wall end of the stairs, which will invariably appear on account of the shrinkage of the stairs and base, but unless carefully watched it is likely to be omitted, as the fitting and tongue-ing of the base is a difficult matter. In the second or "English Method" the finished stairs are put together at the shop and brought bodily to the building and fitted to the rough stringers. In this construction the wall ends of the steps are grooved into the base or wall stringer and wedged and glued. The outer stringer, if a close or curb string (Fig. 76), is tongued and fitted into the treads and risers. This method of "housing" is also sometimes used when the stairs are built at the building. One objection is found to the English method where the stairs are plastered underneath, in that there is no good chance to fit and wedge the finished steps to the rough work, but where the underside of the stairs are panelled there is ample opportunity to wedge the work solid, which is necessary to prevent squeaking, a very disagreeable thing in a staircase. In open string stairs, before the end nosings are put on, the treads should be dovetailed at the end for the balusters, and when these are fitted in, the nosing will make them secure. This should be done in all good work, although the general practice is to nail the balusters at the bottom.
Fig. 73. Winding Stairs.
Fig. 74. Tread and Riser.
Fig. 75. Open String.
Against the sloping rail the balusters may be securely nailed, but the rail must be secured to the posts by bolts made for the purpose which are let into the end of the rail. (Fig. 77.) Where the stair rail comes against the wall it is better to put a half-post than to allow the rail to run into a plate, which will be done unless the half-post is shown or specified. The erection of the stairs should be closely followed by the superintendent, as there is a great opportunity to slight their construction. If put together at the building, the rough stringers should be carefully verified to see that the treads are level and the risers all equal. The cutting of these stringers is a matter of great nicety, and mistakes are often made which the workmen will sometimes try to remedy by tipping the stringer backward, if it is too long, or forward, if too short (A, Fig. 78), or by reducing or adding to the top and bottom riser (B). This should be watched for and never allowed, as a slight difference in the height or level of the steps is a source of danger. If the English method is used, especial care must be taken to see that the finished work is securely blocked and wedged.