A Guide to Building Outdoor Stairs
Building a stairway can be one of the most intimidating tasks any builder–amateur or professional–tackles. But an outdoor stairway is generally not a difficult project, as long as it is planned and executed carefully. This document covers building procedures for a straight-run utility stairway, typically used on porches and decks.
Local building codes regulate the width and slope of a staircase, as well as how the assembly is supported and braced, how the landing is built and whether railings are required. ALWAYS CHECK WITH YOUR LOCAL BUILDING DEPARTMENT BEFORE DESIGNING A STAIRWAY, AND FOLLOW ALL LOCAL CODES.
The following instructions are intended as general guidelines only, and local requirements should be your primary guide.
In this document you will find information about:
- Stair-Building Terms
- Designing Your Stairs
- Building Your Stairs
|TOOLS AND MATERIALS|
|2×10 Stringers||Hex Bolts||Hammer|
|1×8 Risers||16d Galvanized Nails||Carpenter’s Square|
|5/4″ or 2″ Tread Material||8d Galvanized Nails||Measuring Tape|
|2×6 Pressure-Treated Cleat||4×4 Posts||Adjustable Wrench|
|Angle Iron||2″ Railing Material||Joist Hangers|
|Anchor Bolts||Baluster Material|
FIG. 1 – How a stairway is built depends primarily on the total rise– the vertical dimension from the upper floor to the lower floor. The total run–the horizontal length of the stair assembly–depends on the slope of the stairway, which is determined by building codes.
From the Sunset book, Basic
STAIR BUILDING TERMS
- There are five basic design elements you’ll need to consider when planning outdoor stairs:
- The Total Run (Fig. 1) is the total horizontal distance covered by the staircase, from the edge of the upper floor (porch or deck) to the edge of the staircase where it rests on the landing.
- The Total Rise (Fig. 1) is the total vertical distance from the surface of the landing to a point level with the surface of the upper floor (Note: You can’t find the rise simply by measuring straight down from the upper floor because the ground directly below may not be level with the landing).
- Run (Fig. 2) is the horizontal distance from the leading edge of one tread to the leading edge of the next tread.
|Carpentry Illustrated, © Sunset Publishing Corporation.
FIG. 2 – The components of a stairway, with basic stair-building terms. From the Sunset book, Decks, © Sunset Publishing Corporation
FIG. 3 – The components of a railing. From the Sunset book, Decks, © Sunset Publishing Corporation
width for the handrail.
|STEP 2||DESIGNING YOUR STAIRS
FIG. 4 – Common tread-to-riser ratios. From the Sunset book, Decks, © Sunset Publishing Corporation.
a fractional remainder, so round your result up or down to the nearest whole number.
- Then divide the total rise by that number to find the exact height of each riser. For example:
- Total rise = 40-1/2″
- 40-1/2″ divided by 7″ per riser = 5.78 risers
- Round 5.78 up to 6 risers, then 40-1/2″ divided by 6 = 6.75″ or 6- 3/4″ per riser
This document assumes that the total run is not limited, so you can make the assembly as long as you want. Use the following table to determine the width of the treads, depending on your riser height.
|Riser Height||Run Width|
- To find the amount of material needed for risers, simply multiply the number of risers by the passage width. To find the amount of tread material, subtract 1 from the number of risers (you’ll need one fewer tread than risers) and multiply by the passage width. Remember to double up if you’ll be using two boards for each tread.
- To find the length of the stringers, you’ll need a calculator with a square root function. First, find the total run (number of treads multiplied by the width of each tread).
- Then find the square of the total run (total run multiplied by itself) and the square of the total rise and add them together.
- The square root of the result gives you the exact stringer length; round up to the nearest standard lumber length, then multiply by the number of stringers you’ll need.
FIG. 6 – Stringers may be hung from the rim joist with a joist hanger so the first step is flush with the deck surface. In this configuration, a piece of pressure- treated lumber is bolted to the landing pad and the stringer is nailed to it with 16d galvanized nails. From the Sunset book, Decks, © Sunset Publishing Corporation.
FIG. 7 – The stringer can be bolted to the end of the joist so the first step is one step below the surface of the deck. At the landing pad, the stringer may be fastened to an angle iron (the angle should be galvanized) bolted to the concrete. From the Sunset book, Decks, © Sunset Publishing Corporation.
BUILDING YOUR STAIRS
- To build the staircase, first notch the stringers for the treads and risers. Fasten two stair gauges to a carpenter’s square at the dimensions of the rise and run (for example, at 6-1/2″ on one leg and 13″ on the other). Set the square on the stringer so the gauges are flush against the edge and trace the notch along the edge of the square (Fig. 5).
FIG. 5 – Set the carpenter’s square on the stringer so the riser and tread dimensions are at the edge, then trace along the square. Move the square to the previous mark and repeat the process. Subtract one tread thickness from the layout at the bottom so the last step is equal in height to the rest. From the Sunset book, Decks, © Sunset Publishing Corporation.
- “Step” your way down the stringer, repeating the process until you have laid out the correct number of notches. Use the carpenter’s square to lay out the top cut on the stringer. The height of the last riser should be less than the others by an amount equal to the thickness of the tread. That way, when you nail the last tread in place, the step down to the lower floor will be equal to the others.
- You can set the stringer directly on the lower floor (typically a landing pad) and bolt it in place with a piece of angle iron, or bolt a length of pressure-treated 2×6 to the floor and nail the stringer to it.
- If you plan to set the stringer on a 2×6, you may have to notch the bottom of the stringer to allow for that piece.
- Once the stringer is laid out, cut the notches partway only, using a circular saw. Take care not to cut beyond the layout lines. Finish the cuts with a handsaw.
- Once you have one stringer finished, set it in place to make sure it is cut correctly, then use it as a template to lay out your cuts on the other stringers.
- You can hang the stringers to the rim joist with joist hangers (Fig. 6), or bolt them in place to a joist (Fig. 7). If you need to pour a concrete landing pad at the bottom of the stairway, set the stringers in place
temporarily and lay out the location of the pad. Pour the pad and set anchor bolts for the angle iron or 2×6 base. Instructions for pouring concrete are in another brochure in this series.
- Once the landing pad is cured, secure the stringers at the top and bottom. Rip the risers to the same width as the height of the riser cut in the stringers. Then cut them to length and nail them to the stringers with 8d galvanized nails.
- Measure the distance from the face of the riser to the edge of the notch cut, then rip the treads to width so they extend 1″ to 1-1/8″ beyond the edge of the notch. If you’re using two boards side by side as treads, rip half the dimension from each board so both will be the same width. Cut the treads to length and nail them to the stringer with 16d galvanized nails.
- To build the railing, first secure 4×4 posts at the top and bottom of the stringer. Notch the posts 1-1/2″ deep and bolt them to the sides of the stringers with 1/2×4-1/2 hex bolts, using a level to keep them plumb. Use decay-resistant lumber for the posts. They should be at least long enough to extend 36″ above the surface of the treads. Leave them a few inches too long at the top so you can cut them after they are in place.
- Measure from the bottom of the stringer up the posts to the location of the top and bottom rails. The top surface of the upper rail should be 30″ to 34″ above the tread; the rail should be about 6″ above the tread. Lay the railing material against the posts and lay out angled cuts for any rails that will be fastened between the posts.
- Cut the railings to length and toenail them with four 8d galvanized nails. If you’ll be using balusters, cut them to length and nail them to the rails. Check local codes for spacing requirements on balusters.