I think we're going to cement them tonight.

So we had existing stairs off our kitchen and just built a mudroom to add privacy for access through the back door.

 $75 for the stairs.

I am ready to educate myself & cement prosperity for me & my family using the experience of all the wonderful people on this site locally & in general like Mark Ferguson.

standard process. 3/4" plywood 1/4" cement backer board, acrylic modified thin set and the key to a good result is the little plastic hooks and wedges that ensure all the edges are flush.

Another reason people did not like the condo was because it was a third floor condo, where you had to hike flights of stairs to get to the unit door.

When you live there, they'll take a little chunk of your income, and more importantly, a chunk of your time doing the PA taxes.WEAR AND TEAR ON THE HOUSE:My stairs froze off my PA house this winter.

I should also add that the stairs to the basement are pretty narrow and the delivery crew had a tough time getting them in there. 

Not to mention if it's a septic system, then you need to make sure the septic tank is rated for how many bedrooms you are making the thing.Structure - Depending on the style, a new stair case may be required, which may require installing a few supporting beams where the stairs go through the upper or lower floors.Fire stops - you will, depending on local codes, be required to have a fire stop between each unit, such as a 1-hr burn rated wall.  5/8" drywall between each unit. 

And the missing stair tread, you should fix that anyways, mold growing in the shower, again, should fix it anyway.