Stairs are about the most complicated piece of carpentry in a house, and when they go bad, repairing and restoring them can be a tricky business.
We started the stair-rebuilding part of our current part-time gut rehab project with a simple goal. We wanted to keep as much as possible of the old work. The house doesn't have much original detail left, so it seemed especially important to keep the stairs: the continuously curving railing from the first floor to the middle landing at the third floor (where it was victimized by a 1940s-era bathroom addition); the gracefully turned balusters notched into the treads; the gingerbread fretwork that trims the side of every step.
There's nothing simple about these stairs. From the first-floor hallway to the first landing, the carriage is an intricate design that follows a curved wall toward the bottom, then straightens out toward the top. The curved part is made in two pieces, which must have been steamed and bent into shape, connected with wooden "stays," which unfortunately are falling out.
Because the house has different levels in the front and back, there are two second-floor landings, joined by three steps. There are also two third-floor landings, one halfway up and one level with the third-floor floor.
Each level has its own problems.
The curved wall needs new stays -- or new curved carriages -- and a new niche. Water that came in when a third-floor wall collapsed and was not replaced damaged the wall and the stair carriages. The niche, in the plaster wall above the stairs, suffered the most, but the whole run of stairs to the first second-floor landing is in bad shape. And we haven't figured out exactly how we will connect the straight part of the run to the curved part.
The first landing was also in bad shape. Water had rotted out the wood lintel of the window below and the joists that supported the landing. The three steps that connected the lower second-floor landing to the upper second-floor landing also served as a bearing mechanism, transferring the weight of the upper landing through the steps to the lower landing. The failure of the lower landing left the upper landing sagging an inch or more out of level.
The next run of stairs, to the landing midway between the second and third floors, was next to the wall most heavily damaged by water, and the final run ended at the level of the third-floor floor that was compromised when the bathroom was put in.
All of the stairs looked and felt so shaky we were continually having to prop them up, nailing extra supports under them, so we could continue to travel up and down. (Fortunately, there's a steel fire escape to be used by anyone who isn't feeling particularly lucky.)
The first question was where to start.
In a gut rehab, one step always seems to dictate another. The first thing we did to the house was replace the third-floor wall, to stop the waterfall and allow the house (and the stairs) to dry out. Since we were working on the third floor already, we replaced the joists and rebuilt the part of the floor that supported the upper run of stairs. (It was nice to have some part of the stairs feel solid, though of course you had to climb a lot of shaky stairs to get to the good ones.)
Now it got complicated. We decided we needed walls at the second-floor levels to connect the carriages to, but walls couldn't be built until the floors were fixed. As it turned out, we completely replaced the floors on the second floor and the first before we framed out the walls next to the stairs. With the walls in place, the landings could be replaced, and the stairs could be supported temporarily.
Of course water had ruined the lintel over the second-floor window, just below the third-floor landing. That had to be replaced with steel so the landing joists could be pocketed back into the walls. The other end of the joists rests on a doubled 2-by-8 header.
Things were starting to feel more solid at this point, but the stairs were still not connected to the landings because the carriages -- the zig-zag pieces of wood that form the step pattern -- needed to be replaced and because the whole stair structure still wasn't level.
It might have been easier and faster at this point to replace the carriages, treads and risers with a "prefab" unit, custom-built to fit the space. But we would have lost the steps and the railing and the balusters and the trim. Instead we decided to laminate HTC new 2-by-12 carriages to the old ones at the sides and to replace the middle carriage completely.