Introduction: Half Height Stair Platform

Welcome to the instructable for building permanent half-steps for a staircase or platform that is too high off the ground for safe navigation for someone with limited mobility.

I built this one for a client of the Tetra Society of North America. Check them out for some neat project ideas.

Due to the nature of the build, needing to fit the front platform surface exactly, there is no commercial alternative to this product beside hiring a contractor to do these things. In Addition, the step was to conform to these specifications:

1. To look natural and like it was part of the house

2. To be sturdy enough for daily use

3.To be comfortable and safe to walk on

4. To be semi-permanent, that is to be secured with fasteners that are removable if need be

Step 1: Design

For basic dimensions and specifications I first met with the client to discuss the project she had requested. Once there I took measurments in her house of her stair heights. In the end, half step number one was approximately 52 inches long, 10 inches wide, and 4 inches tall. Half step number two was 51 1/2 inches long, 10 inches wide and 4 inches tall. I chose to make one corner of the first half step fit snugly into the side because it would make the step easier to navigate and more secure by being less likely to shift. I also chose to make half step one have a rounded edge on one side because it would prevent injury if someone was to fall upon it considering that is has to stick out into the room.

After the meeting, I drew up a 3D-model in Sketchup (attached) that gave me a fairly solid idea of how to proceed with the build process. I thought about what I would have to buy to make this a reality. I also was able to use materials from my local Hackerspace to build parts of it.

Next I emailed to client an invoice (also attached) for the materials and a picture of the product design before I proceeded to make it.
The materials that were free were from the hackerspace, I charged for the rest of the materials, and donated the hours used to build it, the consultation time and the milage on my vehicle.

Step 2: Materials and Tools

The materials changed a little from the invoice but in the end they were largely the same, and the extras came from the hackerspace so I did not charge for any price overruns.

The final list of materials is as follows:

-OSD board of 3/4" and 1/2" thickness of appropriate lengths (will change depending on your scenario)

-1/4" plywood 14" long

-quarter round trim edging

-2" and 1/2' wood screws



-air staples

-softwood lumber for small fastening blocks (four at maybe 1" long)

-a few feet of scrap softwood lumber for the supports underneath

Tools used (from the hackspace)

-Table saw

-Band saw

-pistol drill

-air gun stapler


-1/8" drill bit

-#4 countersink bit


-circular saw

-miter saw

-router with 3/4" radius bit

Step 3: Layout and Cutting Stock to Size

The first cuts to make stock to size are going to make rough boxes with an overhanging lip at the top to match the nose of the other stair. To cut these items I used a table saw for the cuts along the length of the piece and a circular saw to cut across the short dimensions of the wider pieces. A miter saw was used for the construction lumber and quarter round and the cross cuts of the narrower pieces. I also accounted for wood thickness before I cut the pieces. The dimensions I cut for both boxes were:

3/4" OSD

-10" wide by 52" long (x1)

-10" wide by 51 1/2" long (x1)

1/2" OSD

-3 1/4" wide by

-39 3/16" long (x1)

-51 1/2" long (x2)

-41 3/8" long (x1)

-8 1/4" long (x2)

-14 3/16" long (x1)

1/4" Plywood

-3 1/4" wide by 14" long (x1)

2x4 softwood lumber

-4 pieces

-width cut down to 3"

-length of 8 1/4"

Quarter Round

-51 1/2" long (x1)

-42 3/8" long with one side cut to angle of angled side

-many small pieces cut 30 degree angle to make rounded side work

Step 4: Further Cutting

The next step I took is a series of finishing cuts to shape the pieces to the form they needed to be in. In this step I went to the band saw. I laid out the arc of the round side and the angled side and cut them. I found it useful to screw together parts of the box in the back corner around the angled side. This is because I needed a small radius in the back corner because of how the carpet rounded the internal corner on the platforms angle. When screwed together I cut all three pieces of wood that intersect in that corner at once into that radius. On the bandsaw I also made a series of relief cuts into that piece of 1/4" plywood, later soaking it, so it could be bent into a rounded shape. I also cut out pieces of scrap lumber to support the rounded plywood from behind.

After the band saw, To make the rounded over lip of the stair nose, I went to the router. I setup the router table for this cut as free hand routing wasn't possible for me because I wanted a 3/4" radius on a 3/4" piece of wood, leaving no bearing place for the bearing of the bit.

Step 5: Frame Assembly

To attach the pieces to each other I took the OSD board pieces clamped them down in the positions they were to be located along the top board and then I pre drilled, countersunk, and then screwed them together. It would have been much faster to brad nail the thing together. However, personally I do not like to use brad nails for framing like this, brad nails can work there way loose over time, especially in a situation like this where I am building the frame of a step that is nearly free standing. I screwed down through the top, and into the sides. Pre Drilling is a necessity to screw on end in OSD. The countersinking is necessary as well to prevent the flat head screws from cracking the OSD, being so close to the edge and all. I also screwed together the quarter round and the OSD, seen in the fourth picture. Is really could have been brad nailed, however I didn't have short enough nails at the time. The rounded side of half step one also has quarter round on it, that quarter round was cut into many pieces so it could fit around the periphery.

Once the major frame assembly is done I went about putting in extra supports underneath. Shown in picture 2, I used a 2x4 that was cut to 2x3 and then to 8 1/4" long. I made my own angle brackets to secure it on this half step just to try it out, but for the other half step I screwed the 2x3 into the side with the 2" long screws.

Step 6: Carpeting and Underlay

I did research some videos about laying carpet and underlay. However in the end I just went about this the way I would have if I hadn't looked at those videos. This is because laying carpet on a staircase is different from a single step due to the ability to use a knee kicker in some areas and then have greater control over the stretch of the carpet. Therefore in the end I simply air stapled the underlay to the wood frame and the carpet to the underlay. It doesn't produce the best tightest finish, but it does the job.


1.First I took the piece of underlay I had and cut it to the size of the top of the step.

2.Then I stapled it straight down.

3.Next I stapled under the nose at an upward angle

4.Next I pulled the carpet tight, stapled it at the back of the step where the edge would be out of sight.

5. I could have also stapled the bottom edge of the carpet to the bottom of the half step but I didn't, it was stiff enough that it wasn't going to move anyway

Note: I stapled the nose of the stair first. This would seen like the backward way of doing things, however I tried doing it last and the carpet wasn't tight at all. When the nose is stapled last it is much harder to pull the carpet tight because not only are you pulling it, but you are also bending stiff carpet around the nose of the stair. Trust me, it is much, much less hassle and produces much better results to staple the nose first. But that only applies in this particular weird scenario where you only have only one step to work on. It is different for other set-ups.

Step 7: Final Installation

Installation of half step number two required no hardware. The step itself fit very tightly into the space between the wall in the hallway, requiring me to pound it down. That stair is not moving. Half step number one is a different story. What I did there was I took the stair step and cut a tapered slot into the OSD board on the back. Then I took two screws and a piece of wood, tapered to be wider in front, and screwed it to the existing platform face. The stair then slides over the piece of wood which locks into the slot. As it locks down, the stair gets tighter against the piece of wood and the woods' taper pushes the stair into the platform. Easy! Just be sure to get you measurements right for alignment of wood and slot.