How to Widen a Staircase?

Question

Hi all, I looked at a rehab candidate yesterday, an old rowhouse in NE DC. I like the property and will make an offer but I am stumped about how to estimate widening the staircase to the basement. First to clarify: by "wide," I mean the distance hip to hip as you start to go down the stairs, not the depth of each stair tread. This staircase was the narrowest I've ever seen - I am roughly 20" across at the hips and I was having trouble wedging myself down the stairs.

Any idea what is involved in widening a staircase like that? It hugged the party wall of the rowhouse on the right, and opened onto the basement on the left, as I went down.

Thanks! Alison

Any idea what is involved in widening a staircase like that?  It hugged the party wall of the rowhouse on the right, and opened onto the basement on the left, as I went down.

Thanks!  Alison

Walt Payne · Answer

@Alison M. There are multiple factors involved.

One is that the opening through the floor will need to be enlarged. This is easy enough for someone who knows how, but is not a task to be undertaken by the inexperienced because it involves structural integrity. Joists have to be properly supported and  headers properly installed. You will need permits, and this type of project would likely need a structural engineer or architect to do the drawings.

Another consideration is where the extra space is coming from. Would widening those stairs make a hallway too narrow? Would it effect a load bearing wall?  Would it involve ducting, plumbing or electric running through the walls?

Alison M. · Answer

Kristine Marie Poe          The basement can be finished into living space but is not currently finished.  There are laundry, furnace, hwh, etc down there now.

Alison M. · Answer

All important considerations @Walt Payne .  It would be done as apart of a full gut rehab, into an unfinished basement that is just a big open room.  Structural engineer I think would be a must.

Account Closed · Answer

When you say basement, do you mean a utility basement?  Or live-able square footage for bedrooms?

If utility:  Is there ample room for a 30" door at the entrance where the current door is?  If so, that's cutting into what is probably plaster and lathe and making a new door frame.  Using a pre hung door from HD is the cheapest solution materials wise. But most of the cost will be labor to make the opening.

Depending on what you have for a stair base, it may be as simple as redoing each tread with 30" lumber, with an overhang to the left.

If you are talking stairs to downstairs bedrooms or other living area, that's a whole 'nother thing.