At times it’s impossible to assemble a stair and raise or lower it into the stair well.
When the stair strings are boxed and the steps and risers recessed into the string this means that the stair has to be assembled in the stair well part by part.
To make this easier I make at least one string that can be dismounted into 3 separate parts.
You can see an example of a stair built with this technique in this article:
Installing a curved stair and handrail
To make a dismountable boxed string that’s say 36mm thick with 15mm housing;
Take a board that has the same thickness as the depth of the housings and screw it too another board of 21 mm to have the total 36mm.
Make sure the screws are not where the housing will be routed out.
Mark up the board and rout out the housings with a hand router or CNC.
The housings will cut the 15mm boards in two.
Unscrew the 15mm board that is now a lower part I call support and the upper part I call the plinthe.
Glue and screw the support back into place.
Now when installing, the steps and risers can be screwed on to the supports and the plinthe pinned on after everything is in place.
If you keep the screw heads close to the end of the step, they will be hidden when you pin the plinthe on to the string.
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