# Building exterior stairs.

I still recall one particular day when I was an apprentice for a framing crew that was building an apartment complex. The foreman told me to start cutting the stairs to connect the basement to the first floor. "Who me?" I asked as he pointed to the large hole in the floor that dropped down to the basement. The stairs needed a landing and a 90-degree turn. Before this, I'd only assisted the foreman on a couple of sets of simple steps. I went through a lot of wood that day, but learned a great deal through trial and error.

If you have some deck-building experience, follow these step-by-step instructions on your next stairway.

TAKING ACTUAL

MEASUREMENTS

Before measuring, study Fig. A, p. 76, to familiarize yourself with the name of each stair Part, and read "Basic Stair Rules," p. 70. Steps wider than 32 in. should always have more than two carriages. This rule applies for 1-1/2 in. treads. If you're using thinner tread material, you'll need an additional stringer, even at 32 in. Never span more than 30 in. for 1-1/2 in. treads and 24 in. for 3/4-in. treads. The riser boards shown in Fig. A are not necessary but help support the treads and make a stronger set of stairs.

We'd like our steps to be 42 in. wide so well need three carriages, When buying the material for them, I usually buy 2x12s that are twice as long as the total rise so I've got plenty of material to work with. The lumber often has knots or cracks on ends that I like to avoid For our 43-1/2 in. total rise, I bought 8-ft. lenghts of 2x12.

Our deck is 43-1/2 in. above the landing surface as measured in Photo 1. Referring to the rules on p. 70, if I divide 43-1/2 by 7, the whole number is 6. This means I'll have 6 risers and one less tread (5). If I then divide the total rise (43-1/2 in.) by the number of risers (6), I get 7-1/4 in., which will be the rise or height of the step.

For our set of steps, I'd like the front to end up 51-1/2 in. from the front of the rim joist of the deck. If the tread runs are 10 in. each, the front would be only 50 in. away, which isn't quite far enough. If I make them 10-1/4 in. each, I'll get to 51-1/4 in., which is close enough. As a final check, these rise and tread run numbers meet the three stair guidelines on p. 70.

MARKING AND CUTTING THE CARRIAGES

Position your framing square along the 2/12 carriage as shown in Photo 2. Set it onto one of the 2/12s so the rise intersects the edge of the board on the short end of the square and the tread run on the long end.

Use stair gauges as shown in Photo @ to set the correct rise and run numbers. You can buy these gizmos at hardware stores for \$3 to \$4. Each has a set screw you tighten to mount it onto the framing square. Using them is a lot more accurate than repositioning the square each time you move it. Before making any marks on the 2x12, examine it for any knots that might weaken your stairs. Try to position the lumber so that large knots will be cut away. Also, sight down each board and have any crowns face up.

Start by marking your first tread run at least 6 in. up from the end of the 2x12. Trace the inside of the square across the tread run and then go up the rise. Move the square up along the 2x12 (Photo 2) to complete the rest of the tread runs and the rises. If you choose to fasten the carriages us the method in Photo 6, measure the distance from the face of the rim joist to the face of the next joist as shown in Fig. A and cut the carriages to fit. This will give you the length of the support arm. This gets cut away as shown in Photo 2. A precise cut of the support arm isn't really necessary. Just be sure the arm is long enough to fully support the carriage (Photo 6).

To complete the bottom rise and bottom cut of the carriage, use your square to mark the rise minus the thickness of the tread (Photo 3). Add 1/4 in. to trim away later if your landing isn't flat. The 1/4 in. is usually enough to scribe the stair perfectly to the landing.

Cut along the layout lines as shown in Photo 3, then finish the cuts with a hand or saber saw (Photo 4). Now, test-fit this carriage and scribe the bottom as needed. When you're happy with the fit, trace the pattern onto the other carriages and cut them out Notch the front bottom edge of the middle stringer and screw the bottom support into place (Photo 5) with 3-in. galvanized deck screws.

ATTACHING THE STAIR

CARRIAGE TO THE DECK

If you asked 10 carpenters how to attach steps to a deck, you'd probably get nine different methods. Photo 6 shows a good method for attaching the carriage when the deck joists are 2x8 or less. If the joists are 2x10 or larger, you'd have to notch the carriage using this method, and as a result, weaken it. The method in Photo 7 works especially well for larger joists. TIP: If you want open stairs without riser boards, keep the top tread run the same as the others. if you have riser boards, remove 3/4 in. (or the thickness of your riser boards, from the back of the carriages, where the support arm starts, because the face of the rim joist acts as a riser board.

Stairways always looks best if the risers and treads extend beyond the sides of the stair carriage. I usually cut them l in. longer on each side. Measure the width of the carriage assembly and add your overhang on each side and cut them all to length.

Cut the riser boards to width from 3/4-in. thick decay-resistant boards (redwood, cedar or treated pine) and nail them to the carriage with 6d galvanized common nails (photo 9). Me lowest riser will be narrower by the thickness of a tread.

Cut the treads (5/4 or thicker boards are best) to the same length as your risers. Screw these into place (Photo 10) with 3-in. galvanized deck screws. Always drill pilot holes to prevent splitting the wood.

Take a walk up the steps and see how they feel. For steps with more than two risers, you'll need a railing. If the steps extend over 30 in. high, you'll need to enclose the railing and have no open space larger than 4 in. We left our railing off to focus your attention on the stair parts. For information on deck railings and code requirements, see "Ask Handyman," Feb. '95, p. 8.

BASIC STAIR RULES

The first thing to do is measure the drop to the level where the stairs will meet the ground or slab. This measurement, called the "total rise," can be different from just measuring directly below the surface of the deck. The ground may slope up or down, so knowing where to measure is the key.

Study Fig. A to get familiar with the stair parts. Here are the basic rules for a comfortable stair. * The measurements of two risers plus one tread should total 24 to 25 in. * The measurement of one riser plus one tread should total 17 to 18 in. * One riser times one tread should equal 70 to 75 in.

The ideal rise for each step is between 7 and 8 in. More than 8 in. is an uncomfortable step. The ideal tread run is 10 in. Tread runs should never be less than 9 in. and should now be more than 11 in. Always leave a nosing as shown in Fig. A to give a bit of extra food the nosing can be while you cut the carriages; just keep it in mind when choosing tread boards.

To get an equal him for each riser, here's what to remember: Divide the total rise by seven to get the number of risers to the nearest whole number, then divide the total rise by the whole number of risers to get the exact height of each riser.

To approximate the distance the stairs will be from the dock, remember There is always one less tread run than risers. Select a tread run between 9 and 11 in. Add the number of tread to pinpoint where the steps will meet the ground or slab. You can add or subtract to the run so the steps will fall on your desired location.
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