Building Deck Stairs: How To Build a Deck Part 5
In this set of instructions for our deck building series, you'll learn how to
calculate stairway dimensions and build a solid set of steps. If you
haven’t installed your decking, you’ll need to take care of that first. View
the previous video and instructions in this series, Framing and Decking, at
Lowes.com/Videos.
Preparation
01 Be sure that you understand and follow local building codes. You may need plan approval, a building permit, and one or more inspections during the
construction process.
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02 A deck stairway is comprised of one
or more pair of diagonal stringers or
supports and numerous horizontal
treads or steps. Like decks, stairways
can also have vertical balusters and
horizontal rails. A simple deck plan will
have one stairway section or multiple
sections with landings, flat areas that
connect runs. Landings are often used
to change the direction of the stairway.
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03 Stringers typically are made with 2x10
or 2x12 lumber. The stringers can be
notched, or cleats made of metal or wood can be attached to the inside of
stringers to support the treads. Most deck stairways have open steps with
treads only; boxed steps have horizontal treads plus vertical risers (also
known as toe-kicks). These instructions describe installation of a
stairway with notched stringers and toe-kicks. Refer to your deck building
plans for specifics. You can also buy pre-cut stringers.
04 Simple stairways are attached to the deck rim or end joist and supported by a concrete footing. Longer stairways and those with landings will require
support posts. Refer to How to Build a Deck: Setting the Posts for specific
instructions on installing deck support posts.
- Your support posts should be placed at the end of the run (explained in
Step 05). Position them so you can attach them to the stringer or bottom
toe-kick.
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05 Use paper, pencil, level, framing square and tape measure to calculate a stairway run, the horizontal depth of the steps. Most building codes call for a minimum
run of 9", but 11-12" may work better. The rise or vertical distance between
the tread is typically about 7".
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TIP: A shorter rise is usually more comfortable with a deeper run, and a taller
rise works better with a shorter run. A good rule to follow is the sum of the
rise plus the run should equal about 17-½".
1. Calculate the total rise of the stairway directly over the landing. Extend a level or straight 2x4 from the deck surface and take the measurement to the ground below. In our video, the total rise is 34".
2. Divide this measurement by 7", the ideal height for each step. Round this number to the nearest whole number to get the number of risers. In our video,
the number of risers is 5.
3. Divide the total rise by the number of risers. For our example, we divide 34" by 5 to get the actual height of those risers, in this case, 6-7/8". If the result is too short for your preference, reduce the number of risers by 1 and calculate again.
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4. Calculate the run. The example uses two 5/4x6 decking planks for the tread, with drainage gaps about 1/8". We added toe-kicks on the back of each step for a cleaner look. In the example, the unit run will be 11". Refer to your deck building plans for details on the run.
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06 Calculate the length of the stringers.
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1. Refer to a framing square.
- One side is marked in 12ths, allowing you to scale 1' down to 1". For instance, 8'
on a framing square is marked at the 8" line. The smaller lines are inch marks that
make up one foot.
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2. Calculate the total run (number of treads x individual run = total run).
- The example total run is 5 treads x 11" = 55" or 4' 7". Hold the end of a tape
measure along the left side of the square at 4' 7" or your calculated total run mark.
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3. Locate the total rise (determined in 05-1 above).
- In the example, it is 34" (see above) or 2' 10". While still holding the end of the tape measure on the left side, move the tape to the 2' 10" mark on the right side
of the framing square.
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4. With the tape measure on these two marks, take note of the measurement and hold it along the framing square. It will show you the minimum length for the
stringers. In the example: 5' 3", so you will cut the stringers from two 6' planks.
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Making the Stringers
01 Set stair gauges on the framing square at the height of the rise and length of the run.
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02 Hold the square at the corner of the plank, and mark the top step.
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03 Slide the square along the plank and mark the next step.
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04 Continue marking until you have your number of steps.
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05 At the top step, hold the square under the mark and make a perpendicular line.
This is where the stairway will attach to the deck.
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06 At the bottom step, hold a piece of tread where the stairway will rest on the ground. Mark this line, which will shift the stairway down by the
thickness of the tread. Now when you attach the top tread to the stairway,
it should be flush with the decking.
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07 Cut the first stringer with a circular saw, finishing the cuts with a handsaw.
SAFETY TIP: Always wear a dust mask and safety glasses when cutting treated lumber.
- Apply a weather sealer to the cut ends of treated lumber.
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08 Use the cut stringer as a template to mark subsequent stringers.
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09 Cut the next stringer.
- Complex stairways may require multiple stairway runs with landings. Refer to
your deck construction plan for specific dimensions and requirements.
01 Refer to your construction plans and local building codes to make sure that stairway construction will comply.
02 Mark on the deck joist where the stairway will attach.
- The video example stairway is 48" wide, supported at the deck with brackets and
at the bottom step with posts.
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03 Secure the stringers to the deck flush with the top of the joist.
- If using brackets, conceal them by attaching them to the inside of the steps.
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04 Cut all of the treads and, if used, toe-kicks.
- The tread width will depend on whether they are installed on top or inside of the
stringers. Refer to the deck construction plan.
05 If used, install all toe-kicks with screws.
06 If attaching the steps to posts, use carriage bolts to secure them to the posts.
07 Install the treads.
- If using two boards for the tread, use a nail as a spacer between the treads to allow for drainage.