ᐅ Reinforced concrete staircase height difference adjustment

Hello,

we now have our first “small” problem on the construction site.

Our reinforced concrete staircase has a higher first step and a lower last step, so it basically fits.

Now to our problem: the height does not match the floor buildup. With the finish, it will be about 18cm (7 inches) instead of the planned 17cm (7 inches).

First step about 28cm (11 inches)
All others 18cm (7 inches)
Last step 8cm (3 inches) (flush with the base slab)
Top step height (created by screed and floor buildup) 18cm (7 inches)

The stairs are supposed to be covered with wood (28mm (1 inch)).

The screed installer is coming today, and we will look for a solution then, but I would like to get some advice in advance on how to solve this issue.

Either I am missing something, or no matter the buildup, I can’t achieve a consistent stair rise height of 19cm (7.5 inches):

Example calculation (19cm (7.5 inches) finished rise height):

First step: 28cm (11 inches) - 18cm (7 inches) finished floor = 10cm (4 inches) + stair tread 3cm (1 inch) = 13cm (5 inches) - target 19cm (7.5 inches) = -6cm (-2.5 inches)

1st step: 18cm (7 inches) - 6cm (2.5 inches) increase of first step = 12cm (5 inches) + 3cm (1 inch) stair covering = 15cm (6 inches) - target 19cm (7.5 inches) = -4cm (-1.5 inches)

2nd step: 18cm (7 inches) - 4cm (1.5 inches) increase from 1st step = 14cm (6 inches) + 3cm (1 inch) stair covering = 17cm (7 inches) - target 19cm (7.5 inches) = -2cm (-0.5 inches)

3rd step: 18cm (7 inches) - 2cm (0.75 inches) increase from 2nd step = 16cm (6 inches) + 3cm (1 inch) stair covering = 19cm (7.5 inches)

4th step: 18cm (7 inches) - 0cm = 18cm (7 inches) + 3cm (1 inch) stair covering = 21cm (8 inches) - 19cm (7.5 inches) target = +2cm (0.75 inches) (I would rather avoid grinding the stairs)

Can anyone help me here?

Best regards

Florian