Stair-building and the steel square — Key Ideas to Explore

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STAIR-BUILDING AND THE STEEL SQUARE

A MANUAL OF PRACTICAL INSTRUCTION IN THE ART OF STAIR-BUILDING AND HAND-RAILING, AND THE MANIFOLD USES OF THE STEEL SQUARE

PART I—STAIR-BUILDING

AUTHOR OF “MODERN CARPENTRY,” “ARCHITECTURAL DRAWING, SELF-TAUGHT,” ETC. MEMBER OF ONTARIO ASSOCIATION OF ARCHITECTS

MORRIS WILLIAMS WRITER AND EXPERT ON CARPENTRY AND BUILDING

PART II—THE STEEL SQUARE

CHICAGO AMERICAN TECHNICAL SOCIETY 1917

COPYRIGHT, 1910, 1916, BY AMERICAN TECHNICAL SOCIETY

COPYRIGHTED IN GREAT BRITAIN ALL RIGHTS RESERVED

On entering a building, almost the first thing that meets the eye is the staircase and unconsciously it is made to serve as an indicator of the quality of the architecture. If the design is poor or the construction faulty, this flaw immediately gives the visitor a bad impression of the whole building. Furthermore, stair-building is a rather difficult subject and the principles involved are very little understood, which is evidenced by the fact that the layouts as furnished by architects in their plans are often improperly done.

Probably more mistakes occur in connection with the stairway of a building than with any other construction feature. It is with the idea, therefore, of giving a complete though simple presentation of the construction methods as applied to standard design of staircases, that this book has been prepared.

The article discusses straight and winding stairs, stairs with well hole, layouts for curved turns, the proper proportions of rise and width of tread, the design of hand railings and many other problems, the solution of which will be found very useful.

Coupled with this article is a most instructive section on the Steel Square, containing many applications of this useful instrument to roof and other types of construction.

PART I STAIR-BUILDING

PAGE =Stair construction= 1 Definitions 2 Setting out stairs 8 Pitch-board 10 Well-hole 18 Laying out close-string stair 22 Open-newel stairs 32 Stairs with curved turns 34

=Geometrical stairways and hand-railings= 43 Wreaths 43 Tangent system 44 Bevels to square wreaths 60 How to put curves on face-mould 68 Arrangement of risers 74

=Introductory= 1 Specifications for steel square 1 Miter and length of side of polygon 4

=Steel square in roof framing= 7 General problems 8 Heel cut of common rafter 13 Hips 13 Heel cut of hips and valleys 16

=Introductory.= In the following instructions in the art of Stair-building, it is the intention to adhere closely to the practical phases of the subject, and to present only such matter as will directly aid the student in acquiring a practical mastery of the art.

Stair-building, though one of the most important subjects connected with the art of building, is probably the subject least understood by designers and by workmen generally. In but few of the plans that leave the offices of Architects, are the stairs properly laid down; and many of the books that have been sent out for the purpose of giving instruction in the art of building, have this common defect—that the body of the stairs is laid down imperfectly, and therefore presents great difficulties in the construction of the rail.

The stairs are an important feature of a building. On entering a house they are usually the first object to meet the eye and claim the attention. If one sees an ugly staircase, it will, in a measure, condemn the whole house, for the first impression produced will seldom be totally eradicated by commendable features that may be noted elsewhere. It is extremely important, therefore, that both designer and workman shall see that staircases are properly laid out.

Stairways should be commodious to ascend—inviting people, as it were, to go up. When winders are used, they should extend past the spring line of the cylinder, so as to give proper width at the narrow end (see Fig. 72) and bring the rail there as nearly as possible to the same pitch or slant as the rail over the square steps. When the hall is of sufficient width, the stairway should not be less than four feet wide, so that two people can conveniently pass each other thereon. The height of riser and width of tread are governed by the staircase, which is the space allowed for the stairway; but, as a general rule, the tread should not be less than nine inches wide, and the riser should not be over eight inches high. Seven-inch riser and eleven-inch tread will make an easy stepping stairway. If you increase the width of the tread, you must reduce the height of the riser. The tread and riser together should not be over eighteen inches, and not less than seventeen inches. These dimensions, however, cannot always be adhered to, as conditions will often compel a deviation from the rule; for instance, in large buildings, such as hotels, railway depots, or other public buildings, treads are often made 18 inches wide, having risers of from 2½ inches to 5 inches depth.

=Definitions.= Before proceeding further with the subject, it is essential that the student make himself familiar with a few of the terms used in stair-building.

The term _rise and run_ is often used, and indicates certain dimensions of the stairway. Fig. 1 will illustrate exactly what is meant; the line _A B_ shows the _run_, or the length over the floor the stairs will occupy. From _B_ to _C_ is the rise, or the total height from _top_ of lower floor to _top_ of upper floor.[A] The line _D_ is the _pitch_ or _line of nosings_, showing the angle of inclination of the stairs. On the three lines shown—the _run_, the _rise_, and the _pitch_—depends the whole system of stair-building.

The _body_ or _staircase_ is the room or space in which the stairway is contained. This may be a space including the width and length of the stairway only, in which case it is called a _close stairway_, no rail or baluster being necessary. Or the stairway may be in a large apartment, such as a passage or hall, or even in a large room, openings being left in the upper floors so as to allow road room for persons on the stairway, and to furnish communication between the stairways and the different stories of the building. In such cases we have what are known as _open stairways_, from the fact that they are not closed on both sides, the steps showing their ends at one side, while on the other side they are generally placed against the wall.

Sometimes stairways are left open on both sides, a practice not uncommon in hotels, public halls, and steamships. When such stairs are employed, the openings in the upper floor should be well _trimmed_ with joists or beams somewhat stronger than the ordinary joists used in the same floor, as will be explained further on.

_Tread._ This is the horizontal, upper surface of the step, upon which the foot is placed. In other words, it is the piece of material that forms the step, and is generally from 1¼ to 3 inches thick, and made of a width and length to suit the position for which it is intended. In small houses, the treads are usually made of ⅞-inch stuff.

_Riser._ This is the vertical height of the step. The riser is generally made of thinner stuff than the tread, and, as a rule, is not so heavy. Its duty is to connect the treads together, and to give the stairs strength and solidity.

_Rise and Run._ This term, as already explained, is used to indicate the horizontal and vertical dimensions of the stairway, the _rise_ meaning the height from the top of the lower floor to the top of the second floor; and the _run_ meaning the horizontal distance from the face of the first riser to the face of the last or top riser, or, in other words, the distance between the face of the first riser and the point where a plumb line from the face of the top riser would strike the floor. It is, in fact, simply the distance that the treads would make if put side by side and measured together—without, of course, taking in the nosings.

Suppose there are fifteen treads, each being 11 inches wide; this would make a run of 15 × 11 = 165 inches = 13 feet 9 inches. Sometimes this distance is called the _going_ of the stair; this, however, is an English term, seldom used in America, and when used, refers as frequently to the length of the single tread as it does to the _run_ of the stairway.

_String-Board._ This is the board forming the side of the stairway, connecting with, and supporting the ends of the steps. Where the steps are _housed_, or grooved into the board, it is known by the term _housed string_; and when it is cut through for the tread to rest upon, and is mitered to the riser, it is known by the term _cut and mitered string_. The dimensions of the lumber generally used for the purpose in practical work, are 9½ inches width and ⅞-inch thickness. In the first-class stairways the thickness is usually 1⅛ inches, for both front and wall strings.

Fig. 2 shows the manner in which most stair-builders put their risers and treads together. _T_ and _T_ show the treads; _R_ and _R_, the risers; _S_ and _S_, the string; _O_ and _O_, the cove mouldings under the nosings _X_ and _X_. _B_ and _B_ show the blocks that hold the treads and risers together; these blocks should be from 4 to 6 inches long, and made of very dry wood; their section may be from 1 to 2 inches square. On a tread 3 feet long, three of these blocks should be used at about equal distances apart, putting the two outside ones about 6 inches from the strings. They are glued up tight into the angle. First warm the blocks; next coat two adjoining sides with good, strong glue; then put them in position, and nail them firmly to both tread and riser. It will be noticed that the riser has a lip on the upper edge, which enters into a groove in the tread. This lip is generally about ⅜-inch long, and may be ⅜-inch or ½-inch in thickness. Care must be taken in getting out the risers, that they shall not be made too narrow, as allowance must be made for the lip.

If the riser is a little too wide, this will do no harm, as the over-width may hang down below the tread; but it must be cut the exact width where it rests on the string. The treads must be made the exact width required, before they are grooved or have the nosing worked on the outer edge. The lip or tongue on the riser should fit snugly in the groove, and should _bottom_. By following these last instructions and seeing that the _blocks_ are well glued in, a good solid job will be the result.

Fig. 3 is a vertical section of stair steps in which the risers are shown tongued into the under side of the tread, as in Fig. 2, and also the tread tongued into the face of the riser. This last method is in general use throughout the country. The stair-builder, when he has steps of this kind to construct, needs to be very careful to secure the exact width for tread and riser, including the tongue on each. The usual method, in getting the parts prepared, is to make a pattern showing the end section of each. The millman, with these patterns to guide him, will be able to run the material through the machine without any danger of leaving it either too wide or too narrow; while, if he is left to himself without patterns, he is liable to make mistakes. These patterns are illustrated in Figs. 4 and 5 respectively, and, as shown, are merely end sections of riser and tread.

Fig. 6 is a side elevation of the steps as finished, with return nosings and cove moulding complete.

A front elevation of the finished step is shown in Fig. 7, the nosing and riser returning against the base of the newel post. Often the newel post projects past the riser, in front; and when such is the case, the riser and nosing are cut square against the base of the newel.

Fig. 8 shows a portion of a cut and mitered string, which will give an excellent idea of the method of construction. The letter _O_ shows the nosing, _F_ the return nosing with a bracket terminating against it. These brackets are about 5/16-inch thick, and are _planted_ (nailed) on the string; the brackets miter with the ends of the risers; the ends of the brackets which miter with the risers, are to be the same height as the riser. The lower ends of two balusters are shown at _G G_; and the dovetails or mortises to receive these are shown at _E E_. Generally two balusters are placed on each tread, as shown; but there are sometimes instances in which three are used, while in others only one baluster is made use of.

An end portion of a cut and mitered string is shown in Fig. 9, with part of the string taken away, showing the _carriage_—a rough piece of lumber to which the finished string is nailed or otherwise fastened. At _C_ is shown the return nosing, and the manner in which the work is finished. A rough bracket is sometimes nailed on the carriage, as shown at _D_, to support the tread. The balusters are shown dovetailed into the ends of the treads, and are either glued or nailed in place, or both. On the lower edge of string, at _B_, is a return bead or moulding. It will be noticed that the rough carriage is _cut in_ snugly against the floor joist.

Fig. 10 is a plan of the portion of a stairway shown in Fig. 9. Here the position of the string, bracket, riser, and tread can be seen. At the lower step is shown how to miter the riser to the string; and at the second step is shown how to miter it to the bracket.

Fig. 11 shows a quick method of marking the ends of the treads for the dovetails for balusters. The templet _A_ is made of some thin material, preferably zinc or hardwood. The dovetails are outlined as shown, and the intervening portions of the material are cut away, leaving the dovetail portions solid. The templet is then nailed or screwed to a gauge-block _E_, when the whole is ready for use. The method of using is clearly indicated in the illustration.

=Strings.= There are two main kinds of stair strings—_wall strings_ and _cut strings_. These are divided, again, under other names, as _housed_ strings, _notched_ strings, _staved_ strings, and _rough_ strings.

_Wall strings_ are the supporters of the ends of the treads and risers that are against the wall; these strings may be at both ends of the treads and risers, or they may be at one end only. They may be _housed_ (grooved) or left solid. When housed, the treads and risers are keyed into them, and glued and blocked. When left solid, they have a rough string or carriage spiked or screwed to them, to lend additional support to the ends of risers and treads. Stairs made after this fashion are generally of a rough, strong kind, and are especially adapted for use in factories, shops, and warehouses, where strength and rigidity are of more importance than mere external appearance.

_Open strings_ are outside strings or supports, and are cut to the proper angles for receiving the ends of the treads and risers. It is over a string of this sort that the rail and balusters range; it is also on such a string that all nosings return; hence, in some localities, an open string is known as a _return string_.

_Housed strings_ are those that have grooves cut in them to receive the ends of treads and risers. As a general thing, wall strings are housed. The housings are made from ⅝ to ¾ inch deep, and the lines at top of tread and face of riser are made to correspond with the lines of riser and tread when in position. The back lines of the housings are so located that a taper wedge may be driven in so as to force the tread and riser close to the face shoulders, thus making a tight joint.

_Rough strings_ are cut from undressed plank, and are used for strengthening the stairs. Sometimes a combination of rough-cut strings is used for circular or geometrical stairs, and, when framed together, forms the support or carriage of the stairs.

_Staved strings_ are built up strings, and are composed of narrow pieces glued, nailed, or bolted together so as to form a portion of a cylinder. These are sometimes used for circular stairs, though in ordinary practice the circular part of a string is a part of the main string bent around a cylinder to give it the right curve.

_Notched strings_ are strings that carry only treads. They are generally somewhat narrower than the treads, and are housed across their entire width. A sample of this kind of string is the side of a common step-ladder. Strings of this sort are used chiefly in cellars, or for steps intended for similar purposes.

[A] NOTE.—The measure for the rise of a stairway must always be taken from the _top_ of one floor to the _top_ of the next.

=Setting Out Stairs.= In setting out stairs, the first thing to do is to ascertain the locations of the first and last risers, with the height of the story wherein the stair is to be placed. These points should be marked out, and the distance between them divided off equally, giving the number of steps or treads required. Suppose we have between these two points 15 feet, or 180 inches. If we make our treads 10 inches wide, we shall have 18 treads. It must be remembered that _the number of risers is always one more than the number of treads_, so that in the case before us there will be 19 risers.

The height of the story is next to be exactly determined, being taken on a rod. Then, assuming a height of riser suitable to the place, we ascertain, by division, how often this height of riser is contained in the height of the story; the quotient, if there is no remainder, will be the number of risers in the story. Should there be a remainder on the first division, the operation is reversed, the number of inches in the height being made the dividend, and the before-found quotient, the divisor. The resulting quotient will indicate an amount to be added to the former assumed height of riser for a new trial height. The remainder will now be less than in the former division; and if necessary, the operation of reduction by division is repeated, until the height of the riser is obtained to the thirty-second part of an inch. These heights are then set off on the story rod as exactly as possible.

The _story rod_ is simply a dressed or planed pole, cut to a length exactly corresponding to the height from the top of the lower floor to the top of the next floor. Let us suppose this height to be 11 feet 1 inch, or 133 inches. Now, we have 19 risers to place in this space, to enable us to get upstairs; therefore, if we divide 133 by 19, we get 7 without any remainder. Seven inches will therefore be the width or height of the riser. Without figuring this out, the workman may find the exact width of the riser by dividing his story rod, by means of pointers, into 19 equal parts, any one part being the proper width. It may be well, at this point, to remember that _the first riser must always be narrower than the others_, because the thickness of the first tread must be taken off.

The width of treads may also be found without figuring, by pointing off the _run_ of the stairs into the required number of parts; though, where the student is qualified, it is always better to obtain the width, both of treads and of risers, by the simple arithmetical rules.