Home Fix: Dwight Barnett answers home-improvement questions. This week's topic is on how to level the steps of an old staircase.
Q: We live in a 1948, three-level Cape Cod home. The steps leading to our finished basement appear to have been rather rustically homemade. We’ve torn the carpeting and padding off them and they all slant forward, as if they all need some type of shim/spacer underneath the front portion of each step.
I’d love to simply use some type of leverage on each step plank, lift it up a bit and insert a spacer to even it out, then nail that back down and refinish. Is there another solution that doesn’t involve replacing the entire set of steps?
A: There are two things that separate good carpenters from those who simply do a rough framing of a house. One is crown molding, which takes years of skill to develop a beautifully finished product. The other is fabrication of the stairs.
How is this done?
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First, the carpenter measures the height of the stairs from the floor above to the floor below. He then measures the maximum length allowable for the stairs to make sure there is no obstruction at the bottom of the landing.
The carpenter then divides the height of the stairs by 8 inches, the average maximum allowable height of a single riser, and, with any luck, he will get an even number. With an 8-foot-high basement wall, you will almost always end up with 14 steps, with each riser having a height of 7-9/16 inches.
You also have to maintain a 6-foot 8-inch headroom clearance from the risers to the floor or floor joists above. Sometimes that means relocating one of the home’s floor joists or reinstalling it at an angle.
In the 1990s, codes allowed for a maximum of a 2 percent slope of the treads, but that provision does not appear in the most recent issues of the International Residential Code, so your stairs may have originally been constructed with a slope.
If you really want to pry each tread loose and shim them to make them level, use a handy bar. It’s similar to a crowbar, but smaller and with a thinner profile. You are less likely to damage the wood with this.
Hammer the flat end of the handy bar in between the tread and the stair’s stringer and carefully raise the treads just enough to drive in a wood shim. The old wood tread is dry and could crack under pressure.
Since prying will be moving the nail that secures the tread, I would suggest you use wood screws to reattach the treads you shim. Drill a pilot hole first to avoid cracking or damaging the wood.
Dwight Barnett is a certified master inspector with the American Society of Home Inspectors. Write to him with home-improvement questions at d.Barnett@insightbb.com. Sorry, no personal replies. Always consult local contractors and codes.