# Why is the top step of a stair a different thickness than the other treads?

I'm a little confused about the finished floor (at the top of the stairs) and the thickness of the treads. The treads I'm looking at are around an inch thick. The finishing (hardwood, as seen at my local big box store) for the top of the stairs is 3/4" thick at most.

Is it assumed that the top tread nose will be different from the others?

• I'm not sure what you mean by question 1. – Chris Cudmore Apr 26 '13 at 15:48
• If you have 2 questions, you should consider asking 2 questions. Smushing two questions into a single post, makes it difficult for folks to answer. It also makes it difficult to select/vote for correct answers. – Tester101 Apr 26 '13 at 15:58

The top step is not a tread. It's flooring. You buy the stair nose as part of your flooring purchase, not the stairway build. Most manufacturers of hardwood will provide a matching stair nose, but you may have to order it.

Note that the stair nose is a groove. You can also purchase a double-tongue that will slip in that groove converting it to a tongue should you need to.

• So when calculating my rises, I should be able to safely assume that my nose thickness for the flooring part is standardized to be the same thickness as the nose thickness for the stair treads themselves? – milkboneUnderwear Apr 26 '13 at 20:19
• No. It will be the thickness of the flooring. I don't think a 1/4" difference will be noticeable, especially at the upper run out. I've raised steps 3/4" with false treads, which alters the rise at the top by -3/4 and bottom by +3/4, and haven't stumbled at all. – Chris Cudmore Apr 26 '13 at 21:00
• In your picture above, is the "grooved" (non-nose) part of that piece the same thickness (3/4" in my case) as hardwood flooring? If so, then the nose portion would obviously be thicker than 3/4" and then I should be pretty well good to go. – milkboneUnderwear Apr 26 '13 at 21:29
• A variance in riser height of 3/4" should not be an issue for able bodied people, but elderly and other people with ambulatory difficulties could have a problem. They are also the people that could be gravely injured in a minor stumble on a stairway. This is why building codes typically allow no more than 3/8" variance in riser heights. – bcworkz Apr 26 '13 at 22:07
• Yes, the groove end matches the flooring. The nose end hangs out over, and down below the edge of the subfloor, so it's approximately the same thickness of the other treads. – Chris Cudmore Apr 29 '13 at 12:39

Chris is right but not all floors will offer this. Sometimes you have to buy something close enough and stain it to match.

Also install your transition areas first including this. I have tried to retrofit almost all of my transitions to my already installed floor and it is much harder.