Many build stairs/steps on their decking to enhance space and enable easy access around their space. The process of installing stairs can be completed yourself if you are someone who completes DIY projects or by a professional. In order to complete this task, you will need to know the height of the decking from the ground. In order to complete this task yourself, continue reading the step-by-step guide below.

Step 1 Get the Materials You Need

Firstly, you will need to collect all the materials necessary for your project. The materials you will need to install a stair on your composite decking are composite decking boards, railing, posts, post caps, sub rail, bottom rail, spindles, pickets or balusters. Railings are necessary for the safety of you and your family.  

Alternatively, you can buy a composite decking railing set that already contains all the parts. You also need a wheelbarrow which will help you to transport equipment. Additionally, you will need a measuring tape, chalk line, framing square, safety glasses, hand gloves, saw, hammer, drill and trowel. 

Step 2 Mark the Spot You Will Install the Stairs

You must make sure you mark the spot accurately to know how high your stairs will be from the ground. With regard to your stairs, there are two markings you have to do. You must mark where you will attach the stringer to the composite decking. Also, you will have to indicate where you will attach the stringer to the ground.

stairs construction

Step 3 Attach the Stringers

The stringers are the primary support of the stair, and they determine the rise and the angle of your stair. Depending on the type of support you want for your stair, you can use four stringers or more for your stairs.

Ensure to use enough stringers to provide adequate support, especially if your stairs will encounter lots of footfall. You can use treated wooden boards or composite boards for the stringers.

The process of attaching the stringers to the decking is straightforward. After you have marked the place you will connect it; you should ensure that the stringers extend to the ground.

The other ends of the treated wood that you will use as the stringers should touch the ground. Use connectors to fix the stair stringers. You should attach the connectors to the decking and set the stringers to them. Afterwards, make sure the stringers touch the ground.

At this point, you should have dug the foundation and fixed the posts that you will use as support for your railings. Fix the stringers to the posts so that they will stay stable on the ground.

prepare the boards

Step 4 Fix Composite Decking Boards on Stringers

After securing a solid stringer that serves as the frame of your stairs, you can start fixing composite boards to the stringers. You should place the plastic wood boards on one stringer and make sure it runs to the other stringer. The panels will connect the stringers.

The boards are the surface that you will step on when climbing the stairs. After installing the boards, you should fix the amount by which a tread overhangs the riser. We recommend purchasing pre-cut stringers so that it will be easy for you.

If you are not using a pre-cut stringer, you will have to cut the stringers into shapes so that you can place the boards on them quickly. You can use a level to mark the steps to ensure that it is straight.

the rail

Step 5 Install the Railing

Before you attach the railing, you should first check its location. If you place the first railing post outside the stair, you should follow the same pattern when installing other posts.

Also, ensure your railing is easy to grip to ensure maximum safety for you and your family. Next, you should attach rails that will connect the various positions. What you do on one side of your stair should be extended to the other side to provide symmetry.

You should have four rails in total—top and bottom rails on one side and top and bottom rails on the other side. Then, you should set the post sleeves and install balusters to the lower and top rails.


Installing or building stairs on your composite decking is possible to complete on your own if you carefully follow the phases outlined in this article. Ensure complete safety when completing any DIY garden project.

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