There is no code disallowing risers over 4" high.

Skip the architect, please. Find a stair builder and make sure you're sitting down when he gives you a ballpark estimate.

Leave it be unless you want a 75K-100K rebuild of 2 floors of the house with structural changes.

It’s grandfathered as long as you don’t touch it. And you shouldn’t touch it. It fits the house beautifully, and the house would take a big financial hit if it were to be changed. The whole house should be preserved. It has great bones that are highly appealing to today’s buyer. Nothing worse than a remuddle that is setting your money on fire to make it worse, and make it worth far less.

I like the plexiglass idea -- preserves the light coming from the lower level (wish my bi-level stairs could accomodate something like that!), and fixes the safety issues that are the real problem. The stairs themselves are beautiful!

Thanks for the feedback. Unfortunately with young children in the family, this is an accident waiting to happen, so for safety I have to forge ahead. @Joseph Corlett, sorry I was not clear. I didn't mean that risers themselves have to be over 4 inches. In my research on Houzz and on other sites, I have read that the current codes (which I know change depending on where you are in the country) require that the space where a riser would be must be narrow, 4 inches or less, if they are to be left open. If they are closed with an actual riser, then this does not apply. Am I understanding this correctly? This house was built in the 70's, so would be grandfathered in as @Sophie Wheeler referenced. We had some other work done and the building inspector commented on the stairs, but couldn't do anything since we were not working on them at the time.

Your stair is beautiful and in keeping with the style of your house. It just needs to be made safe. The best way to do this and preserve the look of the stair is to use transparent materials, perhaps acrylic at the risers as suggested (although it scratches), and glass at the balustrade (although it won't be cheap). Talk to a stair builder and see what the options are and what costs might be. Once you've decided what to do, make sure the building inspector is on board with your solution.

Whatever you do, DON'T demolish and replace the stair. The light and openness is worth preserving, and it can be done while making it safer.

By the way, the comment re $75-100K rebuild is BS. Ignore her

Acrylic is just too soft and scratches much too easily for this application. Please make sure your changes are inconspicuously reversible.

No inspector in the last thousand years would have approved this. Treads barely two feet wide? No balusters? A stringer resting on a floor vent? Normal, safe rise/run is 7/11, but this looks like 7/7!!!

There's no fixing this mess. Tear it out and start over.

A rise/run pitch of 8/9 is permissible by current code in most jurisdictions for residential construction. It's steep, but allowable. If the pitch is steeper than that, the stair should be replaced.

Oh boy, my turn! Leave the open treads, they are cool. The 4" spacing in the current code is a joke and there is no saftey issue there. The open railing is another story. I personally climb mountains with my kids so I'm not afraid of open rails but if you had to make a change, add stainless cable rail. That will match the style of the house and get your safety. $10k all in. Good luck

some ideas that keep the homes character

Everyone has given me a lot to think about. @Beth, thanks for the photos, they give me a starting point for this project. My goal is to maintain the current character of the stairs.