Just build the walls. It really is not that hard to do or have done. Anything else will be a stop gap/half measure and noise will always be an issue. So just build the walls now. Let her pick the paint color and she will LOVE IT. It is so sweet of you to consider her needs. We all deserve a space of our own!

I would also build a wall. One thing to consider is if there ducts/vents in the space to supply HVAC to the room and would you be able to fit a closet in the space along with the bedroom furniture.

Before you head to home Depot? Why don't you DRAW/measure the entire bonus room, add in the windows, add in the door, all the half walls and the step. With accurate dimensions on all of it? I mean the entire space, not just a nook you may intend to create. Do that please?

Yes I would need a floor plan I am having a hard time imagining a bed in that space and at least a dresser if not a closet.

What room are these half walls in? I agree it seems much too small for bed/closet etc. If the half walls came out and you divided the space that is left in half would there be a realistic bedroom space?

Your daughter must be so excited to have her own room.

Is the entire room just for her?

The room already has walls. There are lots of things you could do in the space without build more walls. Yikes, that would turn the space into a cave!

“Bonus room” is often a builder euphemism for a room that lacks proper egress to be considered a bedroom. Check local codes before you create a firetrap.

Posts like this always make me a bit nuts. So much missing information! I wanted my own room when I was eight. The problem was my youngest sister was TWO. Therefore, a far earlier bed time......naps etc. And thus it remained and I shared with my six year old sister until they were both older. Four years at least, I believe I got my own room at 12. ....and they shared from that day forward.

We know nothing here. Not the size of the whole space, Not what the eight year old is currently sharing and with whom in that space.. We don't know if the entire bonus space could be sacrificed to the eight year old. Or if there may be a way to give her more privacy in the room she shares.

See what I mean? You don't just bang up walls. Or maybe you do! But based on a plan......