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When was the maximum riser height changed to 8-1/4"?

Which code? As far as I know it did not change in the '21 IRC, not in the 1st edition nor in the errata. But, it is different in some state codes, like the NC residential code, where it is 8 1/4".
 
jar546 said:
When was this changed?
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Not sure what your exactly asking but I will take a stab at this.

The ICC IRC & IBC have never had 8-1/4" residential risers in the model code.

The first ICC IRC I can think of was the 1998 version modeled off the CABO 1&2 family code.

I don't remember if BOCA allowed 8.25 for resi as an exception, "GLENN pull the book off the shelf" Try 93? first

Anyway, many northern and mainly northeastern states because of the high use of masonry block and brick with limestone and blue stone treads modified on adoption to allow the continued use of this form of construction till this day.

NJ & PA are 2 that I know of off hand.
 
This is why I ask. I have an ulterior motive.

I am concerned that Chat GPT AI will make internet searches useless and take traffic away from websites such as this. With that in mind, I asked GPT AI a question and got the wrong answer. See below.

In Florida, the maximum riser height for stairs in a single-family residence is also 8 1/4 inches (210 mm), according to the 2020 Florida Building Code (FBC), which is based on the International Residential Code (IRC).

Like the IRC, the FBC also specifies that the maximum height of risers in a flight of stairs should not vary by more than 3/8 inch (9.5 mm) within a flight, and that the maximum height should be measured from the top of one tread to the top of the next tread. Additionally, the minimum tread depth for stairs in a single-family residence in Florida is 9 inches (229 mm), and the maximum nosing projection is 1 1/4 inches (32 mm).

It's worth noting that the Florida Building Code is updated on a three-year cycle, so it's possible that these requirements may be revised in the future. As with any building code, it's always a good idea to consult with your local building department to ensure compliance with all applicable codes and regulations.
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With the revsions and changes over the years i have been doing enforcement, there is little I am sure about in the code without verifying the edition the building was built under and the current requirements for newly constructed buildings
 
The 1992 CABO code had 8 1/4" risers. This is the earliest edition I could find on-line.
archive.org

CABO: One and Two Family Dwelling Code : Council of American Building Officials : Free Download, Borrow, and Streaming : Internet Archive

BY ORDER OF THE EXECUTIVE DIRECTOROffice of the Federal RegisterWashington, D.C.By Authority of the Code of Federal Regulations: 24 CFR 200.926b(c)Name of...
archive.org

I think the maximum was originally 8" It was increased to 8 1/4" sometime in the 1970s or 80s so that a house with precut (93") studs, single bottom plate & double top plate, 2x8 joists, and 1" of subfloor and underlayment (8'-9 3/4" total) could still have 13 risers.
 
Sorry JAR, I misunderstood. I thought you had found a code that increased it to 8 1/4" instead of looking for when it decreased from that. However, as stated some codes do allow an 8 1/4" riser. I'm not sure if your question was specific to a particular code or in general. If specific, then it would be provably wrong, if not, it could be debatable and require a more nuanced answer...something the cylons were never good at.
 
Sifu said:
Sorry JAR, I misunderstood. I thought you had found a code that increased it to 8 1/4" instead of looking for when it decreased from that. However, as stated some codes do allow an 8 1/4" riser. I'm not sure if your question was specific to a particular code or in general. If specific, then it would be provably wrong, if not, it could be debatable and require a more nuanced answer...something the cylons were never good at.
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My point is that when I asked Chat GPT, it gave 8-1/4" as the answer which is wrong.
 
= = = =

IMO, even if someone asks ChatGPT or a similar platform,
a Code related question, it would be prudent & wise to
research other reliable sources to verify the answer [ as part
of the complete due diligence of the matter ].

Remember, ...ChatGPT is only one source and NOT the
final, complete [ possibly inaccurate ] source.

= = = =
 
Your code section number?

IRC 2018 Section R311.7.5.1 Risers: 7.75
IRC 2018 Section R311.7.11.1 Treads of alterating tread devises: Rise height of 9.5

AWC 6: 7.75 max height

I've had a coulple of deck builders tell me "So and So city allows us to have an 8-inch rise but haven't heard of an 8.25.
 
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