How To Build Stairs: Wood Stairs, Interior Stairs & Even Spiral Stairs

Whether you’re a do-it-yourself homeowner with a desire to build your own stairs, or a seaoned professional, here’s a complete, step-by-step guide. These instructions have been developed through the years by experienced craftsmen and designers and are accepted as the industry standard. Follow them carefully and you’ll build stairs that are beautiful, strong and durable.

Basic Rules for Laying Cut or Designing Stairs
Treads & Risers; The Rise and Run

Three basic rules have been developed for determining the correct width of treads and height of risers for inside stairs for the maximum ease in ascending or descending.

Rule 1: The product obtained by multiplying the height of the riser (from tread to tread) in inches, should be between 70 and 75. Thus, either a 10 inch tread and a 7 inch riser, or a 9 inch tread and an 8 inch riser are acceptable. But a 9 inch tread and an 8 inch riser does not result in a good stair, so a better rule is to make the product equal at least 75, eliminating stairs with too sleep a rise. However, where space does not permit otherwise, this is acceptable in basement or attic stairs.

Rule 2: The sum obtained by adding the width and height in inches of one tread and one riser should be 17 or 18 inches. Thus a 10 inch tread and a riser from 7 to 8 inches high, or an 11 inch tread and a riser from 6 to 7 inches high would be correct under this rule. Rule 1 should now be used as a check on this rule. In doing so, we find that a 10 inch tread and an 8 inch riser are ruled out because the product is too much, (80) while the 11 inch tread and the 6 inch riser are ruled out because the product is too little (66). Thus a 10 inch tread with a 7 ½ inch riser works out as the most satisfactory combination.

Rule 3: The sum of 1 tread and 2 risers should be between 24 and 25. Thus a 10 inch to 11 inch tread with a 7 to 7 ½ inch riser would be most acceptable.

For main staircases in houses, risers should not be higher than 7 5/8 inches or less than 6 5/8 inches (with 7 inches as the most desirable) combined with a tread width (face to face of risers, not including nosings) of 10 ½ to 11 inches. Risers for attic and cellar stairs may, if necessary, be as high as 9 inches, although this extreme height is very undesirable and should be avoided whenever possible.

The height from floor to floor is usually fixed by considerations independent of the stairs. It is evident, then, that the higher each riser of the stair, the fewer risers and treads there will be; and the fewer treads there are, the less space the stairs will occupy. This is why attic and cellar stairs usually have high risers and narrow treads.

Determining the rise and run of a stair is accomplished by applying one or all of the three rules mentioned. Knowing the height from floor to floor in inches, divide this height by 7 inches, which usually gives a whole number and a fraction. For example, if the floor to floor height is 9 feet (108 inches), this divided by 7 inches is 15 3/108. This gives you the number of risers (15) to use so as to have a riser height of about 7 inches. Then, dividing the floor to floor height of 108 inches by the number of risers, as in this case 15, gives you the actual riser height of 7 3/16 inches.

Knowing the number and height of the risers, the width of the treads (from face to face of risers) can be determined by applying one or all of the three rules. If there are 15 risers, there will be 14 treads, because the number of treads is always just one less than the number of risers. The width of tread desired (in this case, say 10 inches) multiplied by the number of treads (14) gives the run of the stair from the face of the first riser at the bottom to the face of the last riser at the top. In the case being considered, the run will be 14 x 10, which equals 140 inches, or 11 feet and 8 inches. If this run is too great for the space available, the width of each tread may be reduced just a little without violating the rules set forth. If the run is still too great, then reduce the number of risers to 14 and the number of treads to 13. The height of each riser will then be 108 inches divided by 14, or 7 5/7 inches, which is still within the allowable limits with a 10 inch tread. The run of the stair is thus reduced to 13 x 10 inches, which is 130 inches, or 10 feet and 10 inches.

Headroom

In framing the wellhole, it is very important to remember to provide for the proper amount of headroom. It has been established by designers and stair builders that the correct headroom measured vertically from the top of the tread at the face of the riser to the lowest part of the finished ceiling or soffit above is 7 feet 4 inches. This clearance varies with the steepness of the stairs, increasing slightly with steep stairs, and decreasing with flat stairs. The question of adequate headroom arises when two or more flights of stairs are arranged one above the other in the same stair well, such as a cellar stair under, or an attic stair above the main stairway, and must be considered most carefully. Although the minimum requirements of FHA (6 feet 6 inches) are much less than the recommended minimum heights set by the experts, it is not advisable to plan a stairway with the headroom less than 7 feet 4 inches.

Width of Stairs

Main staircases should be planned with a minimum width of 3 feet, and where space permits, a width of 3 feet 6 inches is much more desirable. These dimensions have been determined by the necessity of having the staircase wide enough so that two people may pass comfortably on them.

It is also important that the fact be kept in mind that furniture will have to be moved up or down the stairs. Stairs of the narrow “U” type, or closed string stairs, are the most inconvenient from the standpoint of moving furniture, especially if there is a narrow landing or winders. For example, the minimum clear widths of stairs between faces of rails and newels and finished walls for either wide or narrow “U” type stairs to allow free movement of a few of the items of furniture most likely to be carried up or down stairs are as follows: Double bed box springs, 3’2”; Dressing table, 2’5”; Bureau, 2’8”; Average Divan, 4’4”; Highboy, 4’4”; Dresser, 4”4”; Desk, 3’2”; and Chest of Drawers, 2’7”.

With a staircase of unlimited headroom, these dimensions may be reduced by a few inches. If the width of the stairway of a narrow “U” type is 3 feet, the landing must be at least 3 feet 4 inches, and preferably 3 feet 8 inches, to allow for the movement of the furniture.

Rough Horse Table

Height Number Riser Cut in Number Tread cut in
Finished floor to of Rough Horse of Rough Horse
Finished floor Risers Approximate Treads Approximate

7’ – 8” 12 7-21/32” 11 9” to 9 ¾”
8’- 0” 13 7-3/8” 12 9 ½” to 10”
8’- 4” 14 7 1/8” 13 10” to 10 ½”
8’- 9” 14 7 ½” 13 10 5/16”
9’- 0” 15 7 3/16 14 10” to 10 ½”

Introduction Built-up Stairs

The market for Pre-Assembled stairs is unlimited and with good volume potential. Apartment projects, multi-housing developments, or individual homes builders are prospects. The nice part of it is that carpenters in the field like to work with Pre-Assembled stairs because installation is easy. Only a few minutes is required to secure the unit in its proper place, saving time and money.

Each order is easy to write. To help us properly build your stairway, fill in the correct information requested by our company order form. The proper form is included with our catalog and online. Order forms are available upon request. When filling out an order form, consider the type and thickness of lumber to be used. This information is filled in at the top of the form. We will need to know the style stairway required. Seven (7) types are illustrated Here (click to view types) and go to the Knowledge Center Page for descriptions of each stair Type.

Important Notice—Read Carefully:

All assembled stairs fabricated by our company are built from kiln-dried lumber. In addition, we use a non-waterproof glue. Exposure to moisture will result in the deterioration of the glue and a separation of stair joints once the wood dries out. Stairs should be stored under cover where they will be adequately protected from moisture. Our company will not be responsible for damage incurred as a result of improper storage, handling, and/or exposure to water, snow, and other severe outside weather conditions.

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