Basement staircase

In June 2014, the basement of our house was renovated. One of the jobs that had to be done as part of the preparations for the renovation, was to remove the existing staircase. The lower part of the stairs were immured in the floor, so the only way to do that was to cut it off. The work was close to the floor and wall, so motorized equipment was out; however, the beams were approx. 3cm by 20cm so with a regular hand saw this would have taken ages. Luckily, some heavier duty equipment was on hand so it was easier than expected.

Of course, with the existing stairs gone, we needed to install a new staircase when the renovation was done. The ideal new staircase would have to satisfy a few requirements though, which made an off-the-shelf solution unlikely to fit well.

The plan

The basement is 4m long, and from hallway-floor to basement-floor, the height difference is 1.8m. With the stairwell starting about 1m from the wall in the hallway, this left about 3m to the far end of the basement. The plan was to have a fridge and a freezer side-by-side at the far end, which meant that the staircase would have to stay at least 1m20 from the far end (60cm depth of the fridge/freezer, and 60cm additionally to allow the door to fully swing open. Ideally, some more room would be left so that it is possible to stand on the floor while still being able to open the fridge or freezer.

Looking at the plan above, the extension of the staircase should be sc + f <= 1.80m. Say that we want f to be 0.3m-0.5m, that would leave about 1.2m-1.5m maximum extension of the staircase. This is quite a bit steeper than the usual +/- 37 degree staircase. From experience with my previous home-made staircase, this kind of steepness combined with normal steps will result in too small “step depth”; only your heel will fit on the next step, which makes for a difficult staircase to descend. (Going up is no problem, since your foot will comfortably fit between the steps.) In Dutch this is called a “miller’s staircase”, because this design was necessary in windmills where a lot of height needed to be covered with as little extension as possible, but it requires you to descend the stairs facing the steps instead of facing away from the steps, which is not what we want for our basement staircase. We can improve on this by making the steps asymmetrical: if we make the steps wider on the end where you will rest your foot, and smaller on the end where your other heel will pass on the way to the next step, this will allow to use the full width of the step for support.

With regards to height, the floor-to-floor distance is 1.8m. The ideal distance between steps is 0.15m to 0.20m, so a quick calculation gives 9 steps with 0.20m top-of-step to top-of-next-step distance.

Making the staircase

The wood I used for making the staircase is regular pine wood: 2.7cm thick, and 19cm wide, straight from the DIY store. Our local specialized wood business has nicer wood in many more dimensions, and probably also at lower prices, but for the relatively low quantity needed for this project I didn’t feel like dealing with the waiting times, during work hours, and the chaos in their shop.

Step 1: the carrier beams.

For the previous staircase I made, I made a mold to make cutting the grooves for the steps at the correct angle easier. I reused that mold, which made cutting the beams at the bottom to right angle a breeze. At the top there was some more work, because I wanted the staircase to rest on the hallway floor. I had to cut a wedge into the beams to make that possible.

Step 2: the steps

First, the steps are cut to length, and then each step is trimmed on one side to be about half the width. Then, the step noses are rounded off:
Then, the ends are trimmed to fit the grooves that will be made in the beams: Finally, the steps sanded and varnished:

Step 3: Preparing the beams

The beams were already cut to length, so the work that is left is to cut the grooves in which the steps will fit. This job needs care and precision, because both beams have to be mirror images of each other. The grooves for the steps have to be at the exact same heights and angles in both beams, so that the steps fit without stress. I used the mold from the previous staircase, but it needed some adjustment to allow for the wider beams in the new staircase.

Step 4: Trial fit

Trial fit of beams and steps. In these pictures, you can clearly see how the asymmetrical steps alternate to allow “passing of the foot” on the way to the next step:

Glueing and installation

Putting it together was not entirely easy. It took a few attempts to get the steps nicely lined up on one beam so that the other one could be put on top without any of them falling over. When the top beam was in place (and all the excess glue wiped away), I made sure that the steps were at right angles with the beam and the pressed everything together and let it dry overnight.

A final layer of varnish later, the clamps and straps could be removed and the staircase is ready to be installed: