They look solid to me - but I don't claim to be an expert.

Highly likely solid, considering it's a winding staircase. This is more custom than off the shelf of so called engineered stair treads.

No pro but looks solid to me too

Why do you ask? It's a lovely stairway.

I’m asking because our currently carpeted stairway is shaped like this, and I’m getting conflicting recommendations from different contractors on which material to use.

As soon as I get home I’ll post a pic of the surface under the carpet.

So you're looking to replace the carpet, and make the stairs look more like the ones in the photos? That would be my preference - but it isn't going to be cheap, to get it done right! I'm not sure you'd get that look with engineered wood. I'm not even sure why someone would want to put engineered wood on a staircase, when solid wood treads give such a beautiful result.

Yes, I want wood stairs, we know it won’t be cheap. I don’t have my own opinion on the material, but I had presumed solid wood was preferred. I’m trying to learn what is ideal. I was surprised that 2 contractors recommended engineered and 1 recommended solid treads (but not pieced together). So now I’m wondering about the twisting/warping with that person’s recommendation.

We already have solid wood floors downstairs.

As Uptown Floors explained, "solid" wood treads are not cut from a big tree - they are made from smaller pieces glued together. Look at the first photo you posted - you can see the stripes of different grain. These are different pieces of wood. But they are assembled and glued so well that they act as a single piece of wood - without the propensity to warp that would happen if they were sliced from a tree in one piece. Your contractor who recommended solid treads was referring to treads exactly like those shown in your photo.

Good luck with your project!

I’ve tried 3 times to post pics. I’ll try again as separate posts.

The bottom is the open, curved part, then 2 landings, then closed straight stairs to the top and a large landing at top.

I’m going to have to wait until I’m home tomorrow, and then I can load the pictures onto my computer and try to post them from there. They just aren’t posting from my phone. Thank you for all the feedback.

Since they have a bullnose edge and the wood grain continues from the top, they have to be solid. If they were engineered, you would be able to see the layers from the curved front edge.

Lars,

Good point about the grain continuing around the bullnose. I appreciate everyone weighing in.

I am the OP, but for some reason HOUZZ switches my username depending if I'm on my phone or on my PC.

Anyways, it sounds like solid wood, pieced together, is the way to go.

Here is pic of what is under my currently carpeted stairs:

Front the top down, that's a mid-landing, then riser, then a stair tread.

Have any more pictures? This will certainly be a challenge with what appears to be false treads or some kind of end cap. False treads are often short pieces aligned on both sides with carpet running in between.

I see some age as well with the plank sub flooring on the landing.

Uptown Floors,

Thanks for your reply. We are not going to DIY this. And we know it will be challenging and expensive. We haven't decided on a contractor to hire yet because we've gotten such varied recommendations.

The carpet, end caps, balustrades, newel, and railing will all be removed and replaced. What we want is new treads to run all the way across and have returns on the open side. A new railing, newel, balustrades, and trim are needed.

The house is 30 years old; we didn't build it.

I can take more pictures.

I figured no DIY. I've spent a lot of time and years installing hardwood floors. Now semi-retired. I think back to similar jobs. I wouldn't touch it myself, but learned a great deal over the years in watching professional stair guys. I'd always call them in.

Here's one recent job (Grand Cayman) before pictures. New construction, poured concrete. The first three treads and risers required templates.