Thread: step riser height code date

Anyone know when the following (or similar) was first adopted in to code?

R311.5.3.1 Riser height.
The maximum riser height shall be 7¾ inches (196 mm). The riser shall be measured vertically between leading edges of the adjacent treads. The greatest riser height within any flight of stairs shall not exceed the smallest by more than 3/8 inch (9.5 mm).

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Basically in the 2000 IRC.

Before that many codes used the two-risers-plus-one-tread-equals-between-24-and-25 rule.

The maximum riser height in many of those codes was either 8 inches or 9 inches, with a minimum tread of 9 inches plus a 1-inch nosing.

Thanks for the quick reply Jerry.

So, is there a way to imagine that risers at almost 9 inches were ever allowed?

Cape code 1945.

Originally Posted by John Dirks Jr

So, is there a way to imagine that risers at almost 9 inches were ever allowed?

Yep. Could have been allowed back then.

However ...

Like a guard rail with 12 inch spacing openings - just because it was 'allowed back then' does it make it any safer than why it is not allowed now?

Someone falling down a stairs with a 9" riser is not going to care whether the stair was constructed "to code" in 1945 or whether it was built yesterday as non-conforming and would fail an inspection ... they are still falling down the stairs.

Well, here's the report comment I came up with. I really struggled with this one. Ya think I should have just left it alone?

1. The step risers for the stairs between the first and second floor are almost 9 inches in height. Current local codes do not allow step riser heights of more than 7 3/4 inches. This rule is based on the issue of safety. At the time this house was originally built there were other formulas in use to determine limits of riser heights but I cannot find any specific reference that would allow a riser height to be higher than 8 ¼ inches. Having said all that, you should be aware of the higher risk of personal injury relative to higher step heights such as those in this house. If it concerns you, consult with a qualified contractor on what can be done about it.
Here is some background of previous calculation menthods.

Some background from older codes: Stairways for residential dwellings used to have a formula applied to their design to limit their slope from being too high, limit the height of the risers, and require a minimum depth for the tread. That formula used to be "Two risers plus one tread equals between 24 and 25", combine that with the maximum riser height (which varied by state, many states were 7-3/4", some were 8", and some - like NY - were 8-1/4") combined further with a tread depth (which also varied by state, many states allowed a minimum tread depth of 9" but required a 1" nosing for tread depths less than 10") would all calculate out to a 'reasonable' slope stairway.

Here is an example: A stair has risers which are 8" and a tread of 9", that would calculate out as 8+8+9=25. That would be the steepest allowed slope because if the riser heights were the allowed 8-1/4" the total would be 25-1/2 with the minimum tread. Likewise, the opposite would be a stair with a riser height of 6" and a tread of 12", for 6+6+12=24. The latter example *would* fall within the allowed "two risers plus one tread equals between 24 and 25", however, that formula was not really designed to control less steeply sloped stairs, it was designed to control and limit the steeper sloped stairs.

Seems to me you went a bit overboard on that one John. I'm all about stair safety and handrails. I like to inform my clients about the 'what if' because quite frankly as professionals we know what some of the 'what ifs' are better than the client. I'm not thrilled with the verbiage on that paragraph. I don't have a better one for you right now but will give it some thought.
If the stairs are original to the vintage house, I discuss options and modern standards with the client. I'll put a note in the report about good handrails, etc but that's about it.
If the stairs are new and non-compliant, I'll slam the living _rap out of them. Especially fun when it is a new house with a permit. Had another one of those not long ago.

"Existing stair risers of approx. 9" do not meet current code standards of 7 3/4" and may present a significant danger while traversing especially to those unfamiliar with the stairs." If this is a 'sale' inspection I seriously doubt the seller is going to take steps (pun intended) to resolve a potential non-issue.

Originally Posted by Markus Keller

Seems to me you went a bit overboard on that one John. I'm all about stair safety and handrails. I like to inform my clients about the 'what if' because quite frankly as professionals we know what some of the 'what ifs' are better than the client. I'm not thrilled with the verbiage on that paragraph. I don't have a better one for you right now but will give it some thought.
If the stairs are original to the vintage house, I discuss options and modern standards with the client. I'll put a note in the report about good handrails, etc but that's about it.
If the stairs are new and non-compliant, I'll slam the living _rap out of them. Especially fun when it is a new house with a permit. Had another one of those not long ago.

I'm not surprised with your thoughts. Like I said, I struggled with it and decided in this case, for me anyway, a bit over was better than a bit under.

I still have a copy of my 1991 California UBC, section 3306 reads:
The rise of every step....not less than 4 inches or greater than 7 inches....run not less than 11 inches....

Exception: private stairways serving less than 10, 8" maximum rise, 9" minimum run...

Originally Posted by John Dirks Jr

Thanks for the quick reply Jerry.

So, is there a way to imagine that risers at almost 9 inches were ever allowed?

Cape code 1945.

Yep, still are; spiral stairways for example.

John
Here are 2 diagrams of the old stair riser/ tread code and the new.

I would mention what you insert something like this within your report; "It should be noted that the stair is equipped with minimum horizontal depth treads (steps) and maximum vertical height risers, which may have been acceptable at the time of construction. However, it is suggested that due caution be used in using the stair to help prevent potential trip/ fall accidents resulting in personal injury."

The new code requires a minimum of 10 inch treads and maximum of 7-3/4 inch risers per attached diagrams.

PS: you may want to add this visual to your report for further emphasis?