Building stairs can be easy and quite rewarding, understanding some basic building code requirements and following a simple guide can have your project done quickly. This article is number one in a series on planning and building your outdoor dream deck. Read all about that project right here.
After understanding all about stairs you can learn all about railings right here!
Outdoor staircases come in many different styles that are specific to the deck style and terrain of the project.
If you want to be sure and get some free expert advice contact your local deck designer.
6 important stair terms to guide your project
Landing pad is the base that the stairs will sit on, this can be gravel, concrete or masonry stones, whatever the medium it needs to be level, at least as wide as stairs and large enough for users to get a footing at beginning or end of climb. The landing pad also helps to prevent premature rot often seen when wood sits in water or next to ground.
It is typically a 2 x 10 or 2 x 12 that runs at an angle from the deck surface to the landing pad supporting the actual steps.
Open Stringer is when you can see the notches and the side of the steps.
Closed Stringer is when the steps rest on a cleat attached to the side of the stringer.
Treads are the boards that you place your foot on as steps, typically double 2 x 6 or 2 x 10 material.
Rise or “Unit rise”
Rise or “Unit rise” refers to the distance you raise your foot from one step to another. Risers can also reference the boards that fill in the back of the steps to make closed steps (can’t see between steps).
Total rise is the overall vertical distance between the top of deck and landing pad. How far the stairs rise!
Total run is the overall horizontal distance from the edge of deck to where the stairs end. How long the stairs run!
Code Requirements to ensure your stairs are functional and safe.
These are generalizations, reader must consult their local building department for specific requirements. Codes are the minimum requirements so if in doubt go stronger.
- Stairs should be at least 36” wide.
- Maximum distance between stringers is 2’11”. Stairs wider than 36” require a mid-stringer. Stringers support the treads so consider the tread material and adjust closer when using materials such as composite or 5/4 board.
Tip: It is always interesting that deck boards need to be supported every 16 or 24” depending on the decking material used however stairs that take far more of an impact load can be by code 36” on center, code is the minimum!
The maximum unit rise (from top of one step to the next) should be 7-7/8” and the minimum should be no less than 4”. 7-1/2” of a rise is considered the optimum comfortable step for people to take.
- Tread depth should be at least 9-1/4”. Typically treads are a single 2x10 or double 2x6. Consult composite lumber manufacturers for stair details.
Tip: The combination of run and rise should equal 17-20" for the step to be comfortable. If your rise is 6" then your run or tread width should be at least 11"
- Effective depth must be at least 3-1/2”. The effective depth is the remaining material left in the stringer after the run and rise are cut out (open stringers)
Tip: The longer the stair stringer the more you should consider increasing the 3-1/2” required by code to 5 plus inches or going to a closed stair stringer.
- Hand rail required if there are more than 4 risers (not four stairs but risers). If a hand rail is required;
- Must be on at least one side of the stairs
- Must be 1-1/4” to 2” in diameter, square or rectangular permitted with similar requirements to be able to comfortable grasp hand around rail.
- There must be 1-1/2” space between wall and rail. This requirement is to ensure someone can get their hand around rail in case of emergency.
- Hand rails should be mounted between 34” and 38” from nose of stairs, this is considered a comfortable height for users.
- Hand rails should extend from top of stairs to bottom.
how much an outdoor stair project will cost
Stair cost can vary depending on the conditions and style of your deck project. If cutting stair stringers is a daunting task you can purchase pre-cut stringers at any lumber yard.
The stairs on our deck project required four risers therefore a guard and hand rail had to be installed. The stingers were closed and riser boards installed. We added in a third stringer and poured a 3x4 concrete slab for a landing pad. Without labour we were able to stay within the 200.00 budget.
6 steps to complete your outdoor stair project
Step 1 Determine the total Rise and Run.
- You will need a helper to hold a long level off the top of the deck, measure between the top of the deck and the location where the stairs will sit, considering finish of landing pad. This measurement is your total rise.
To calculate the number of risers:
Divide the Total Rise by 7-1/2”
E.g.: If total rise is 33”/7.5” then 4.4 risers
Try rounding up and down
Round down to 4 risers divided by total rise (33”)= 8.25” (8-1/4”) Too large a rise!
Round up to 5 risers divided by total rise (33”)= 6.6” (6-1/2”) Good enough!
- We now know there will be 5 risers at 6-1/2” each.
Using the consideration that the total of the run and rise of each step should be between 17 and 20” for a comfortable stair,
17” less 6-1/2” = 10-1/2” or 20” less 6-1/2” = 13-1/2”
Therefore tread width (front to back) should be between 10-1/2” to 13-1/2”. If we use 10-1/2” per stair (runner) then our total run (distance from deck face to landing pad would be
Total Run= Tread width * (number of risers-1)
Total Run= 42”
Step 2 Prepare a landing pad
The landing pad is the level ground where your stairs sit and you step off onto. The top of the landing pad needs to be level to the height determined in step one as your total rise. The landing pad needs to be located at least the total run away from deck edge, less 6-8” to rest the bottom of the stringers on.
Step 3 Cutting stringers
The two critical measurements are the rise 6-1/2” and the stair width of 10-1/2” (you may want the stairs to have a bullnose, which will require that you adjust landing pad distance slightly) Using a framing square mark your two critical dimensions or purchase stair gauges, which makes laying out stairs quick and most important accurate.
Tip: Hold framing square in front of you so 90 degree edge is in your chest and thin and shorter side is in your left hand and thicker longer side is in your right. On the left side closest to you mark your riser (this case 6-1/2”) on the right side closest to you mark the tread width (this case 10-1/2”) These marks from left to right, closest to your chest now form each stair, do not flip or rotate just move down the length of stringer the number of risers necessary.
Before you start to mark your stringer make sure you orient wood so crown is up (front of stairs). There will be only two cuts on the side stringers as these are closed stairs, so go ahead and cut the bottom and top at the angle indicated.
On the top of the stringer the angle to support against the rim board is simply the left (small side of framing square) line extended towards your body.
On the bottom step extend the right (large side of framing square) line to inside of stringer. Along the line measure 6-1/2” and mark a 90degrees perpendicular line. This cut will provide the foot for the stringer to rest on the landing pad.
After you have double and triple checked measurements you can use a skill saw to cut.
Tip: Make sure your skill saw blade is in good condition and square to base plate.
Test the first stringer by putting in place between rim board and landing pad. The top and bottom of stringer should be in full contact with surface and all treads lines level. If acceptable then trace and cut second stringer.
Cutting Mid stringer- The mid stringer is a little more difficult to understand, but it is as simple as laying out the same as the closed stringer but reducing the bottom step by the thickness of the tread (1-1/2”).
Step 4-Tread blocks or cleats
As two of the stringers are “closed” in this project we need to add blocks for the treads to rest on and be secured to. The blocks are cut to the width (front to back), of stair treads and finish these 2x4 blocks on a 30degree angle and sand well before installing with screws and outdoor wood glue. The angle and sanding are simply for appearance.
Step 5- Installation
The tread boards should be given a sanding and then installed using screws and glue. The set of stairs can now be leaned into place and positioned so that the first step is the correct rise (6-1/2”) from top of deck and treads are level. To secure stairs to outside rim joist mount blocks on the inside of the stringers to the rim joist and screw through side of stringer into blocks. Screws through the back of the rim joist into the stringer should also be added for additional support.
Tip: Position stairs and mark mounting block locations, remove stairs and install blocks firmly in place using screws and glue.
If your deck requires guards then so do your stairs. Follow the same style of approved railings. The mid-posts should be installed at the top and bottom of the stairs and at least every 6" on center. Well built and maintained stairs limit your homes risk of accidents. Provide transition form one outdoor living space to another. And can provide a sitting area or even a stage during large family gatherings.
Unfortunately stairs are a cause of many injury compensation claims. Ensuring your deck stairs are built at least to code, will limit the impact of such claims. Non slip products applied to treads such as tapes or paint products will help to eliminate the risk of slips. Lights added to stairs helps everyone navigate better. Additional handrails (one on each side) is another great way to reduce likelihood of falls while on the stairs.
if you have been following our series on decks you can appreciate a project like this can be quite complex. Using quinju.com home improvement project software will help keeping everything organized as you will have your own home renovation binder available at all times.