Our last house had a closet with a slanted floor. The basement stairs were behind it. It made sense to us, but we were second owner.

In small houses I recall the closet floor in the room over stairs being stepped. That way you still have level surfaces for storage. The stair ceiling is slanted beneath the steps. If the floor is finished you may want to try and match it.

It would be wise to have someone knowledgeable determine whether there is a structural beam and/or wiring or plumbing in that area before you start to tear things out.

Until you open that ceiling you will not know what you are able to do. I would investigate and see if you can hopefully drywall on the angle.

We did the stepped interior in the bedroom area above and created a closet out of it. the ceiling of the stairwell is slanted now.

We had a structural engineer come and ultimately our contractor put a beam on the attic floor to ” hold up” the space .. i wont be home again till early May so cant show pics of beam but you definitely need an engineering consult about load bearing.

We had to do ours as it was low enough in our 1910 home that my husband who is 5'11" hit his head every time he came down the stairs and if we hadn't had an old exterior stairway, since removed, we wouldn't have been able to get most of our furniture upstairs !! It's the angle/distance as you step from one step down to the next that causes the head banging .

My husband the retired engineer said it also depends on which way your joists run, but there's no way this isn't a major structural change, so consult a professional. You may need both a contractor and a structural engineer. Our first house was built in 1910 and was also like this. Honestly, unless someone in your household is 7' tall, I would just live with it. Just think of it as part of the old house charm.

As pointed out by several above, you MUST know how the framing was assembled behind the surface before a workable change to the current design can be made.

Kudos to Kudzu9 and others for bringing up the point of finding out exactly what exactly is there. If there is only a header holding up the closet wall that can probably be raised and a slanted floor created in the closet. If you do create a slanted floor I might suggest adding wood strips to the floor. That will make an excellent area to store shoes. Good luck!

Seems like a big project for little gain.

How much too low is the headspace?

In the grand scheme of things, a bit of framing carpentry and drywall work is all that it would take to either cut it to a slant or make a step in the closet. It would be simple to assess the work be removing the drywall. Snap a photo of the framing behind it and we can give you a good read on the difficulty.

stepped not slanted I grew up in an 1920's farm house and that is how it was built.