This is how it turned out .

correct !

Hi Duayne,

I agree with you and Mark about the way to go about cladding this stair except I would problably use laminated bendy ply to build the curved outer string. 

Is the outer string going to be a boxed string or cut string?

Risers and skirt will be mitered 

I would fix verticals onto the steps and build a laminated stringer above the steps with 7mm bendy ply. with the outer laminates in 2 or 3mm veneered of the finished wood. 

Will use 2 pieces of 6 mm fir cut with the grain in the vertical position with veneer on the outside ,  it bends easily and tends to keep it’s shape better .

I would make the outer laminates in 2 or 3mm veneers of the finished wood. For the outer laminates, you can also use veneered 5mm ply wood that has been thinned to 3mm by passing it through a drum sander. This will bend nicely and can be cut to the full width of the string, the only problem being that it’s very fragile with the veneered layer only 6/10mm.  

I would make the outer laminates in 2 or 3mm veneers of the finished wood. For the outer laminates, you can also use veneered 5mm ply wood that has been thinned to 3mm by passing it through a drum sander. This will bend nicely and can be cut to the full width of the string, the only problem being that it’s very fragile with the veneered layer only 6/10mm.  

Once lowered into place, if it’s a boxed string I would mark the step positions  and machine a shallow housing around 10mm into the string to receive the step collets and risers.

This makes it easier to have a perfect joint as butting up the steps and risers on the  curved string  is going to be tricky.

It’s cut but I can handle the tricky part . 

The steps can be scribed against the back edge and the outer curved wall and placed with over hang so that you can just draw around the concrete to have the exact shape. Add the extra nosing and outside length to penetrate into the curve stringer.

I would, as Mark suggests and glue the strings, steps and risers to the concrete.

As Mark said rising humidity might be a problem if the stairs are not perfectly dry. 

If they are in anyway humid I would wait until they are dry .

To let the wood “breath” I would run parallel grooves under the steps and risers so that the air can circulate between the wood and cement.

Another good idea !

I would glue them to the cement with hard polyurethane laid out in ribbons, again not trying to have a tight fit so that air can circulate between wood and cement.

The outer string and step and riser cladding could be time-consuming but should be fairly straight forwards .

The joint to the curved wall is a bit trickier if you have to add a curved plinth. Although if the plinth can be painted it could be made of bendy ply.

On this side it might be better to butt the steps and riser up to the plinth, at least if they are slightly housed into the outer string they you can play a bit with the length and push them up to the wall stringer / plinth to get the best fit possible.

I will think about that one !

I am thinking about 10 days on this one . 

In this case it would be best to make and install the wall plinth before the steps and risers.

I would glue it up above the steps and then scribe it to the cement step and risers. No need to have a tight fit as the steps and riser will be covering up the gap.

Are you going to build a handrail on this stair ?

 Metal guys are handling that part , they are installing the glass also .

Cheers,

Ness

That’s pretty much how i intend to do it , the risers are the one place that i have some leeway , i think i will build them out with some 3/4″ plywood , it will give me something to anchor the risers and treads to ,  good idea about the damp proofing  , i will have to look into that !

I will build a temporary curved wall along the inside wall and laminate the stringer to that !

The stairway is a commercial job that was originally supposed to be covered with tile of some sorts , the owner decided that he wanted something different and  decided that he wanted hardwood with a glass banister , I was mainly interested in different ways to fasten the risers and treads to the concrete without making it look to obvious , we are already pushing the limit on the rise for the top and bottom steps so i really have to install the treads directly on the concrete , I have decided to build out the risers and fasten the coverings with  that .