Rotating a staircase and making a new landing. How do I support it

Question

I am looking to rotate this staircase. Instead of descending in a southerly direction, I would like them to descend to the east. To do that my plan is to make the top step (step 5) into a landing and take move/rotate steps 1-4 to be toward the camera.

The thing I am concerned about is the fact that column A (the column supporting the handrail) is not particularly structural. It's just screwed into the floorboard.

Column A would need to be moved much farther east, and replaced with a "structural" column for the south east corner of the landing, as well as a new handrail column.

My question is about the new "structural" column. How should I make it structurally sound?

My initial thought was to cut a hole in the floor and lag bolt it to the joist, but the joists are engineered and I'm not sure if they are rated for that kind of attachment.

My second thought was to drop the column all the way to the floor of the crawl space and pour a small concrete pad in the crawlspace, have the column sit on that, but frankly that sounds awful.

Is there an option I am not thinking of? Is there a safe way to attach a vertical column to an engineered joist? Is it legit to attach a column to a joist?

I have plans to move the intake or make the stairs "floating" and move the outlet.

Answer 1

You've asked some good questions. However, your project is going to be a bit easier than you think! You won't need a column & footing just to erect a small landing to re-route your staircase. If you have any doubts, you can consult an engineer, who will accept your money and then tell you the additional dead load from the landing is no big deal.

So how do you support your new landing?

You can frame it directly on top of your plywood sub-floor. You'll be building a short L-shaped wall to enclose the new landing. This is accomplished with ordinary 16" on-center 2x4 framing. Support your relocated 5-step staircase the same way.

Blocking between the I-joists

You should install blocking between your I-joists to provide additional support for the wall(s) which will support the landing. Do that before erecting the walls, that way, you can nail the bottom plate of your new walls, through the subfloor, and into the blocking.

More resources

My guess is you may not have much experience with framing. Check your local library for a book about framing walls. I like the Black & Decker Complete Guide to Walls & Ceilings and it should be easy to find in many libraries and home improvement stores. Also, the book Building Stairs by Andy Engel is really great, with lots of illustrations, and I think it will help you a lot with your project. In particular, it may give you some extra confidence when building your new handrail posts.

I hope this helps.