IMO just close off the railing and call it a day. When closing off these open areas you often run into issue with heating and cooling the window if left wi;; need to be safety glass since it will be lower than now. Could you post to scale plan of the upper floor I think I see an office are you sure you want a play room next to an office . You will need some pro help here to do this anyway so why not get some help now as to cost for sure . Also how old are the kids ?

Thanks Patricia! I did not think about the issue with heating/cooling :(. The issue with closing off the railing is that we don't actually create a new space, it will only create privacy. I don't have a birds eye view of the floor plan but the door to the left is the office. It's basically a hallway right now so we wouldn't get any benefit if we only close it off. We might even want to just make that room even bigger to create a flex room (and create play area elsewhere). So, not married to the idea of it being a dedicated playroom but do want to create more space.

If we do close off the landing to create privacy, will it look weird next to the other railing?

This seems like a big project for not really much more space.

I agree with @bichonbabe. I think once you have a contractor price it you will have sticker shock. I am not a fan of two story foyers, but once you have one it is hard to retrofit it to be something else, especially with a window like that. What is the problem you're trying to solve? Need more space, or need space in a different location? Do you want a play area next to the home office? Can you show the whole second floor and describe the problem you're trying to solve? Or consult an architect by presenting the problem. It's their job to come up with lowest cost solutions. Sometimes when you're too close to the problem it's hard to see a solution.

If the constuction cost to create a floor and usable space here is worth it to you, adding another material such as white lap siding to the whole inset doorway area should work and then the window can be re-sized. I’d speak with an architect and then contractor to get a feel for the costs and benefits.

I have seen it done, but on the other side, where you are gaining the whole space above the family room. That small foyer space won't be worth the cost, specially when you have to replace the window and do brick work.

How is it possible for someone to see into that window ? Are the homes and walkway past the house a ton higher than your house . I find it almost impossible to see up into windows on a 2nd floor. I honestly think what you are planning really makes no sense .

If the issue is privacy, that can be addressed with translucent films. This is a bunch of work for the extra 75 sq/ft.

Ignoring the opinions of whether or not it is worth the cost, one idea is to push the railing closer to the window but still leaving a gap of several feet. Swap out the railing for something as transparent as possible, sinceas people have noted privacy isn't really an issue and you don't want to block the natural light. You will gain interior space without affecting the exterior.

And actually the cost wouldn't be that great. Framing the floor is pretty easy given the small span, then you just need to extend the flooring and finish the underside and end.

@Mary Iverson this is genius!! Thank you for sharing!!

We have simmilar layout with bathroom door in the view. privacy film fix it, and added nice decorative element.

@RappArchitecture

What would estimate that cost for that extensions for framing and drywall work?

Looks pretty narrow to be worth all of the work. A flex space/playroom will need furniture. Imagine how little floor space you have left after that. I get this for an upstairs laundry or an extra bathroom, but this isn't much sqft for a flex space.