How to pour concrete steps

Poured concrete steps provide a strong and durable transition between an exterior surface, such as a patio, and the entrance to your home. However, one of the most confusing questions that comes up is how high and deep (front to back) each step should be. The answer to this question lies in some simple math that you can use to calculate the unit of rise and fall.

When considering the total travel of the unit, local codes often require the top landing to extend at least 12 inches beyond the door opening. Subtract the width of a door that opens outward (usually 32 or 36 inches) from the length between the base and the outside edge of the steps. If the rest is less than 12 inches, you may need to change your plan.

Know the codes before you start planning your steps. If you don’t build them according to code, a building inspector can force you to tear them off. The codes may also have something to say about the placement of rebar or other reinforcement, as well as the concrete mix you use.

Expect two to three days to plan, design, and pour three steps (not counting cure time).

STEP 1

Measure Get Up And Run

Measure the site height and run, and stake to indicate where the bottom of the step will be when it is poured. Calculate the unit of rise and fall of the steps and draw a dimensioned sketch.

How to calculate Rise and Run

Unit elevation and unit step travel are individual dimensions for each riser and tread.

To calculate the rise and march of the unit, first divide the total rise by 7, a standard step height. Round fractional results to the nearest whole number. Then divide the total increase again by this number so that the unit increases.

For example, here is the math for a total increase of 20 inches: 20 inches / 7 inches = 2.8, rounded = 3 steps. 20 inches / 3 steps = 6.6 inches. In this example, you will need three steps 6 to 5/8 inches high to climb 20 inches.

Next, divide the total travel (to the outer edge of the door sweep) by the number of steps for the unit to work. For example, if your total travel was 48 inches, here’s the math: 48 inches / 3 steps = 16 inches per tread. However, a 16-inch tread depth would feel too long. Set the tread depth to 13 inches, a more comfortable measurement, and make the total travel 39 inches.

STEP 2

Shoe design

Place shoes 3 inches wider than the steps. Dig footings as required by depth codes, pour concrete, and insert 12-inch lengths of 7- to 8-inch rebar into footings. The top of the rebar should be approximately 2 inches lower than the final height of the steps. Allow the shoes to cure, then dig a 4-inch trench between them and fill it with rammed gravel.

How to anchor concrete steps

With an underlying 1/2-inch rebar grid, the poured concrete steps will give you years of low-maintenance service. Some local building codes may require you to anchor concrete steps to the foundation wall. You can drill at an angle into a poured concrete base, or through a concrete block wall and insert rebar into the holes.

STEP 3

Scheme steps

Using your plan and the actual dimensions you have calculated and sketched, draw the outline of your steps on a 3/4-inch sheet of plywood. Draw the line for the landing so that it slopes 1/4 inch per foot. Attach a second sheet of plywood to the first, the edges flush, and cut the outline of the step with a jigsaw.

STEP 4

Check the square, level and plumb line

Using a framing square to make sure the shapes are perpendicular to the foundation of the house, set the shapes in place and drive support stakes along them. Make sure the shapes are plumb and level with each other, then secure them to the stakes with 2-inch screws. Cut off any part of the stakes above the forms.

STEP 5

Install vertical forms

For each step, cut a piece of wood 2x to the width of the stairs and break it to the height of the unit’s riser if necessary. Bevel the bottom edge of each riser (except the bottom) to facilitate tread float when pouring the steps. Attach the top riser form to the outside of the side forms with three 2-inch screws. Then install the remaining riser forms.

STEP 6

Attach suspenders

Cut the braces at an angle and attach them to the side shapes at the front edge of each step. Next, drive 2×4 stakes to the bottom of the braces. Plumb the side shapes and attach the tie rods to the stakes. To prevent the riser shapes from bending, drive a 2×4 stake 18 inches or more into the ground in front of the steps. Place a 2×6 in the risers and attach to the stake and cleats attached to the risers. Attach an expansion strip to the base with construction adhesive.

VARIATION

How to build perpendicular steps

Steps can run directly from an exterior door or at right angles to it. The shapes of the perpendicular steps go together in essentially the same way as the straight steps illustrated on these pages.

Draw a level line at the base to mark the height of the landing. Measure from this line to position the plywood shapes for the back and side. Stake the shapes together, cut beveled risers, keep them level, and mark their bottom corner on the base. Next, attach the diagonal brace to the house and the foundation and risers to the cleats. Support the leading edge of the risers as you would a straight ladder.

STEP 7

Fill with rubble

To save concrete, time, and money, shovel clean pieces of broken concrete, river rock, or any clean masonry into the space within the forms. Pile the rubble under the landing higher than the first step, but don’t put so much rubble that it will make the concrete on the steps too thin.

STEP 8

Add rebar

To strengthen concrete, bend 1/2-inch lengths of rebar to roughly correspond to the shape of the rubble mound and lay it over the rubble at 12-inch intervals. Connect perpendicular lengths of rod through the first few pieces. Next, lift the rebar and support it on brackets or balusters that you connect to the rebar.

STEP 9

Mix and fill with concrete

Cover the shapes with a release agent. Mix the concrete and bring it to the site in wheelbarrows. Shovel the concrete into the forms, starting with the bottom step and working your way up. Hit the sides of the shapes and risers with a hammer and poke 2×4 up and down into the mix to expel any air bubbles. Give the concrete enough time to settle into the rubble and add more concrete if necessary.

STEP 10

Edge lifters

Run an edger along the inside edge of each riser shape to round off the leading edge of each step to minimize chipping. If you are covering the steps with brick, tile or stone, leave the edges square.

STEP 11

Delete forms

Allow the concrete to set long enough to support its own weight, then remove the riser forms and finish the concrete with a trowel. Use a stepped trowel (a drywall corner knife works too) to smooth out the corners. Sweep the rungs to roughen the surface, allow the concrete to cure, and then install the railing. After 12 to 24 hours, remove the side forms and fill the voids in the concrete.

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