Basement Stair Questions

[Jimmy_B]

Hi CodeMan,

I have a stairway going to the basement from the kitchen that I would like to make more comfortable while at the same time bringing it up to code. It currently has a total of 10 steps; the run of the top step is 7" and the remaining nine are all 10". That top step has been driving me crazy for a while now.

My first question is what is the current stair code in New York state for the rise and run of the stairs? I have been told that the codes have been updated over the last few years but am not sure what the current codes are.

Also, what is the code for minimum headroom height at the bottom of the stairs? The current height when measuring from the landing to the top is 73". From the edge of the first tread to the top is 66" and from the second tread it opens up and measures to 102".

I would just like to educate myself on the codes involved with these stairs before I contact any building officials or start any work.

Thanks for your help,
Jimmy

[Jerry Peck - Codeman]

Hi Jimmy,

The minimum allowed headroom for the 2010 Residential Code of New York State is 6 feet 8 inches. The way you would measure that headroom is fairly simple: take a string and hold or tape it the the top landing (the upper floor), run the string down the front of each tread (the part your foot goes on) and hold or tape the string to the bottom floor - the string 'should' be touching the front of each tread (the front of each tread is the nosing). The string represents the plane of the nosings, now any place you measure vertically up from that string should have at least 6 feet 8 inches clearance before reaching the ceiling, a beam, or anything.

The maximum riser height (the vertical height from tread to tread is the riser height) is 8-1/4 inches (most codes have a maximum riser height 7-3/4 inches, New York State allows for a steeper stair that other codes allow for).

The minimum tread depth (the part your foot goes on is the tread) is 9 inches. The easiest way to measure the tread depth is to take a combination square and set it on one tread where it overhangs the nosing of the tread and adjust the square so it rests on the tread below, now measure from the backside of the square (the backside of the square is what is against the front of the nosing above) and measure to the front of the nosing on that lower tread (using another square on the lower tread makes it easy to measure to the front of the nosing by placing the second square tight to the nosing on the lower tread), you just measure from backside of the upper square to the backside of the lower square - i.e., from the front of one tread to the front of the adjacent tread, but you measure at the vertical planes of the nosings, thus using the square helps establish those two points.

The easy way to layout your stair is to measure from the lower floor to the upper floor (in your case that would be 9 x 10 inches plus 7 inches = 97 inches), then divide that by 8 (use 8 for an 8 inch riser so as to not push the maximum riser height) which would be 97 inches / 8 inches = 12 risers 8 inches in height with 1 inch left. The maximum variation in height between the tallest and shortest risers is 3/8 inch, so you could not leave the 1 inch at any one riser. The next step is to divided 97 inches by 12 risers to see if that will work 97 / 12 = 8.083 inches per riser.

8.083 is just over 8-1/16 inches for each riser, which is within the allowed riser height of 8-1/4 inch. 12 risers x 8.0625 (8-1/16) = 96.75 inches. That means that one riser, I would make it the bottom riser, would need to be an extra 1/4 inch higher than the other risers to make 97 inches, and that would be within the maximum allowed variation of 3/8 inch. Putting the odd riser height at the bottom means that a fall caused by the off-height riser would occur at the bottom of the stair, not at the top of the stair.

The problem, though, is probably going to be headroom as you very well may not have enough headroom to work with based on your description with 66 inches and 73 inches headroom near the top of the stairs. That 73 inches is bad enough, but 66 inches? That one would be a real head banger for sure. Use the string to establish the plane of the nosings and measure vertically from the string to double check those headroom measurements.

The above is from the 2010 New York State code residential code, however, I believe that code is not necessarily adopted and enforced state-wide, which means your local building department may be using a different code, nonetheless, though, the above gives you an quick and easy guide as to how to measure stairs.

[Jimmy_B]

Thanks, Jerry.

This is great information and is just what I needed.

Congrats on having an excellent website.

Jimmy B.

[Jimmy_B]

Hi Jerry,

I took care of the headroom issue on this staircase by removing an enclosed shelving area that I have been banging my head on for years. It opened up the stairwell nicely and I'm sure my forehead is smiling, too.

I now have a couple of other code questions that I would like to run by you. First, the staircase goes down to a landing in the basement before you reach the floor. The landing pad size is 27" from the wall straight ahead to the nose of the bottom tread, and 32" in the other direction. The height from the nose of the top landing step the the ceiling is 71". The landing is 12" high and the height of the basement floor at the bottom of the landing to the ceiling is 83". Does the 71" landing height meet code?

Also, I measured the treads a little more closely this time and came up with the following:
- there are 10 treads and 11 risers
- the lower 10 risers are "open" risers; the top riser to the kitchen floor is not
- the actual tread depth of the lower 9 treads is 12" but each step has a 2" overhang
- the top tread is 7" deep
- the lower 10 risers have a 7" rise and the top tread has an 8" rise

I'm tryng to do the math using the method that you used, but I don't think I am doing it correctly. Could you let me know if I would still be OK with the rise & run measurements that you came up with in your earlier post?

Thanks again,
Jimmy

[Jerry Peck - Codeman]

Hi Jimmy,

The stairs should be 36 inches wide minimum; the landing should be as wide as the stairs minimum; the landing should also extend in the direction of travel from the stairs at least as far as the stair is wide; i.e., the minimum landing should be at least 36 inches by 36 inches.

The riser up to the landing is also too high (12 inches is too high).

With your more accurate measurements, the height from the basement floor to the upper floor is:
- 12 inches (for the landing riser height)
- 70 inches (7 inch risers for 10 risers)
- 7 inches (for the top riser)
- 89 inches is the total height from the basement floor to the upper floor - is that what you get when you measure it?

At a height of 89 inches instead of 97 inches, we could start with the same 12 risers as follows: 89 / 7 = 7.42 inches for each riser height. If we went with only 11 risers, we would have: 89 / 11 = 8.1 inches for each riser height. I personally would opt for the 12 risers over the 11 risers as the stair would not be as steep ... but ... 12 risers means 11 tread versus 11 risers means 10, and each tread adds approximately 10 inches to the run of the stairs, which means you might not make headroom as easily as with 10 treads (that 10 inches for the extra tread sometimes makes all the difference between meeting headroom and not meeting headroom with minimum headroom being 6 feet 8 inches (80 inches).

Do away with that landing at the bottom and just land the stair on the basement floor - unless that landing is there for a reason?

The distance the stair will take up (the run of the stair) depends on the number of treads and the depth of each tread 10 treads of 10 inches each = 100 inches.

The maximum opening size in the guard rail for the sides of the stairs is 4 inches, and the maximum opening of open riser stairs is also 4 inches (just put a horizontal 2x2 in the center across the open riser from stringer to stringer, that will reduce the openings in the open risers to less than 4 inches).

[Jimmy_B]

Hi Jerry,

On the width of the stairs being a minimum of 36" wide, my stairs are 29" wide because the kitchen door is 30" wide. Am I grandfathered in since it is the original door? The house was built in 1958.

What if I only wanted to fix the top step of the staircase to make it it a little smoother and safer, could I just raise the tread and make it longer? The run is currently 7" and the rise is high at 8". The stairs were not built using what I would call a "regular" stringer layout; they were built using 2x10's on the sides with open risers and wood blocks holding up the treads. I have been wanting to fix that top step for some time now, but have not been able to get to it. At this point, I would like to weigh the options of fixing the current setup or building a new set.

Thanks,
Jimmy

[Jerry Peck - Codeman]

Jimmy,

If you only make minor repairs to the stairs there should not be any problems with the fact that the stair is non-conforming. There will be some legal issues if someone falls down the stairs, but nothing that would not already be there for the existing stairs as they are now.

Altering or replacing the stairs would mean the stairs would need to meet current code requirements. Otherwise, there will be greater legal emphasis and responsibilities placed on the person who did the non-conforming work.