Dad says the stairs are fine. Fine is the word for a man who has not yet caught a toe on the nosing at the bottom step. A non-slip tread is one of the cheapest fixes in the house, and it does not ask him to change how he lives. It fails in one specific way, though: the bond. Most treads that come loose were never cleaned, were set in the wrong conditions, or were walked on before the adhesive grabbed. The install is the warranty.
Local option: New Plan Care gives families in the St. Louis area in-home help so a parent can stay home: companionship, help with bathing and dressing, meals, and overnight care. Call (314) 405-0887.
Check the stair before you buy the fix
Measure the depth of each step from nosing to riser, and the width of the stair. Count the steps and write the count down, because the number you order has to match it. Look at the nosing edge. A tread that sits flush against the nosing is the one that holds. If the stairs are carpeted, the carpet has to come off the surface you are bonding to, or the tread goes on top of the carpet, which is a different product with a different risk. Ask the seller in writing whether the tread is made for bare wood, painted wood, or carpet, and whether the version you are buying is adhesive or screw-down.
Pick adhesive or screw-down
Adhesive treads are the faster job, and the only clean way to undo one is with heat, a scraper, and patience. Screw-down treads need the screws to hit solid wood and the heads set flush, and they leave holes you will see from the landing. If you rent, read the lease before you pick adhesive, because many leases say who pays to repair the finish. If you own, decide now whether this stair stays in the house for the next owner. Either way, the job has one owner, one work session, and no one else on the stairs until the adhesive has cured.
Clean, check the conditions, and lay out first
Clean each tread surface with a degreaser that leaves no film, then let it dry fully. Dust, wax, and old polish are where adhesive fails. Read the label for the working temperature range and the cure time. Do not start if the house is outside that range or if the stair is damp. Lay each tread dry first, mark the front edge with light pencil, and confirm it sits square against the riser. If the cure time is long, do one step at a time and keep one handrail side clear so the stair stays usable while the rest cures.
Press, roll, and test it
Press each tread firmly from the middle outward, then roll it with a weight or a heavy roller so the adhesive contacts the whole underside. Let the full cure time run. Test with one controlled step. Dad holds the rail, a second adult stands below, and the tester steps on the center, then the edge, then lifts the nosing by hand. Any lift, creak, or shift means the bond did not set. Pull that tread, clean it again, and reset it. Do not let anyone walk the full flight until every step has passed.
Keep the paper and name the next move
Keep the box, the label, the seller's return terms, and a note of the day you installed each tread in one folder. If a tread lifts later, that folder decides whether you are returning a product or fixing your own work. Dad will tell you it is fine right up until a loose edge catches a shoe. The next move is simple: order the treads that match the count you wrote down, clean the first step tonight, and start the cure timer before anyone else touches the stair.