Building deck stairs is tricky, but this guide makes it easy. Follow the step-by-step guide to learn how to estimate the dimensions, lay the stairs, cut the stringers, and assemble the parts.
A quality DIY deck stair building manual guides you on measuring the shape, height, and width to make a perfect deck stair. However, before we get started with the step-by-step guide on how to build deck stairs, here are a few things that you need to keep in mind.
Table of Contents
Tools and Materials
Here is the list of the tools and materials that you will need to build the deck stairs.
- Framing square
- Circular saw
- Plumb Bob
- Angle brackets
- 1×2 pressure-treated boards
- 2×2 pressure-treated boards
- 2×12 pressure-treated boards
- 4×4 pressure-treated posts
- 2×6 pressure-treated boards
- 4″ galvanized deck screws
- 3″ galvanized decking screws
- Masonry anchors
- Fast-drying cement
- Fast-drying concrete
- Pea gravel
Code and Safety Requirements
- The deck stairs should have at least a 48-inch width. Else it will feel cramped.
- The stair raise should range between 4 to 7-3/4 inches. The longer and the shorter height of the riser should not be more than 3/8 inches.
- If the notch on the open stringer is deep, then it causes the structure to weaken.
- The stair railing should have a handle to grasp.
- Always use a dust mask and eye protection, especially when handling or cutting the wood.
- Thoroughly clean your hands after the work is complete.
- Dispose off the sawdust and other woodworking stuff properly.
- Never burn the wood that is pressure-treated.
Now that we know all the requirements and precautions let us get into the deck stairs’ building steps.
How to Build Deck Stairs?
1. Figure Out the Run and the Rise
You first need to measure the rise and the run of the deck steps. Start by measuring the distance between the deck floor and the ground and divide this number by 7.5. The answer is the total number of steps that you will need to construct. If you get a decimal number as an answer, then round it off to the nearest whole number.
To calculate the rise height of the steps, divide the height by the number of stairs you calculated in the last step.
To calculate the staircase length, multiply the number of steps and the depth of the step. As a standard practice, the depth of the stair tread is usually taken as 10 inches.
Now determine the width of the staircase that you desire. The standard width of the stairs is usually 36 inches.
Figure out the point where the stair and the ground will meet. Mark this area because this is where you will have to place the footer concrete.
2. Preparing the Concrete Floor
You have the spot where you need to build the concrete floor. Excavate this area to a 6-inch depth. Remove all the debris and dirt from this site. The soil should be compact and level, and you will need a tamper for this. Add some pea gravel to a 2-inch height and then level the pad using a tamper.
You would have purchased fast-drying cement. Mix it as per the directions to create the footer for the stairway. Once the cement reaches the desired consistency, pour it over the pea gravel. Fill the hole to reach the ground level. Smoothen and level off the cement pad with a level and a trowel.
Let the cement stand for 24 hours to 48 hours, depending on the weather conditions.
3. Cutting the Stringers
You will need the 2×12 boards to cut the sides of the stringers or stairs. Use a framing square, and then mark the portion that you will cut from the stringer.
Start from the top corner of the board and place the square such that one leg is kept to the measure of the rise and the other is drawn to the measurement of the tread. Trace in the inside edge and draw the lines and then cut it. Move the framing square till the last line comes off the board and make the next mark. Repeat this till you mark all the cut-outs.
You will not need a riser because the top step and the deck will be attached. Instead, draw straight lines along the board corner, creating a return. You will need an extra return for the last stair. It is the section of the step that will sit on the ground.
With a circular saw, cut along the lines and finish it with a hand saw. The first stringer can be used as a template to transfer the marks onto the second-stringer and form similar cuts.
4. Attaching the Steps to the Deck and the Floor
Set your stringers in its place. The bottom end should be rested on the concrete pad, and the other should rest against the deck face. A plumb and a level should be used to check that the stringers are placed correctly. Use angle brackets and galvanized deck screws to attach the stringers to the deck.
Use a 2×6 board and fit it between the two stringers. These are the ones at the base. The board should fit snugly. It will help to bond the stairs with the concrete pad. Now place the board between the stringers. You will need galvanized deck screws to attach the stringers and to hold them in place. Use masonry anchors to secure the concrete pad and the 2×6 board.
5. Cutting and Attaching Treads
Each tread is made using two 2×6 board lengths. For this, cut the trail tread to overlap the stringers by 1 inch on both sides. The treads should be cut a little more than the width of the stair. One tread should be pushed against the back and the second in the center of the stringer.
Fasten them with galvanized deck screws on both sides. Leave a ¼ inch space between the first and the second tread board, and then attach those using deck screws. You will have to keep doing this till all the treads are firmly attached.
6. Constructing the Railings
Cut two post pieces of 4×4 to a 30-inch length. It is the lower post of the railing. You will have to notch out a small portion towards the bottom of the front tread. It will let the rail posts stand against the stringers. Now place the posts at the base of the stringers and mark the tread portion that needs to be removed. Next, cut the tread notch using a hand swathe post plumb. Finally, cut a 2×4 railing length to span the entire distance from the lower post towards the deck’s existing railing.
Now attach the railing to the post with the 3-inch deck screws. You will need to be particularly careful here to see that the slope of the railing matches that of the stairs. Cut pieces to serve as the baluster support and the lower railing. Install the railing between posts taking care to level them parallel to the upper barrier. There should be a gap between the lower railing and the step, but it should be less than 6 inches.
Cut the 2×2 boards. Use it to create balusters to extend from the top to the lower railing. Attach them with 3-inch deck screws to the railing. Ensure that they are plumb and that the gap in between them is not more than 6 inches. To make the handrail comfortable, attach a cap of 1×2 along the entire railing top.
You will neither need a lot of math nor any professional woodworking skills to complete the project. Just follow this DIY guide, get your tools ready, and start building your deck stairs.