Wooden stairs, recessed into the wall
Wooden stairs, recessed into the wall

Concrete stairs with steps recessed into the wall can also be lined with wood. However, in such cases, solid wood is not used, in the form of logs or thick boards. This would result in a not very aesthetic thickening of the step.
The steps in this type of staircase form reinforced concrete slabs thick 7 cm (the most common length 90 cm) laterally concreted into the wall to the depth of at least 20 cm.
The lining of such a step is made of a veneered plywood box slid freely over the step (drawing).

Drawing. A box for a reinforced concrete step built into the wall at the side: 1 - a reinforced concrete step laterally embedded in the wall, 2 - frame made of spruce slats (veneered on the side), 3 - veneer plywood
Such a lining is made like a prefabricated element, including surface finish. The advantage of this design is that the box can be turned after some time, and easy renewal of the varnish coat.
The production of boxes begins with the preparation of wooden slats for three-sided frames. The frame corners are connected with a tenon and fork or nailed. The joints do not have to be durable and are only used to facilitate gluing the veneered plywood to the frame. If the plywood does not have a decorative one, top layer, it needs to be veneered. After sticking plywood to the frame on both sides and sanding the sides, they are veneered with veneer strips with a pattern similar to the top of the plywood. Then the entire box is smoothed with fine sandpaper and varnished.
The box slides over the step without any additional fixings. Cardboard washers will be sufficient. The dimensions of the box in the light should be greater in thickness by 2 mm, and across the width of 4 mm from the cross section of the concrete step.