The rules a wood floor is actually held to
The numbers a stair and a railing are actually held to here
Philadelphia adopts the 2021 International Residential Code as Subcode "R" of the Building Construction and Occupancy Code. That matters more than it sounds, because Pennsylvania amends the model code: the maximum riser height in the Pennsylvania Residential Code is 8 1/4 inches, not the 7 3/4 inches the base IRC sets. A stair built to a number copied from a national article can be wrong here.
- Code adopted in Philadelphia
- 2021 International Residential Code, as Subcode "R" (Philadelphia Code Title 4, Article R-1.0)
- Handrail height
- 34 to 38 inches above the sloped plane adjoining the tread nosings (R311.7.8.1)
- Handrail clearance from the wall
- Not less than 1 1/2 inches (R311.7.8.3)
- Guard height, open side of a stair
- Not less than 34 inches from a line connecting the nosings (R312.1.2 exception)
- Guard height elsewhere
- Not less than 36 inches above the walking surface (R312.1.2)
- Guard opening limit
- No opening that passes a 4 inch sphere (R312.1.3)
- Maximum riser height, Pennsylvania
- 8 1/4 inches, and no more than 3/8 inch variation within a flight (R311.7.5.1)
Handrail and guard are two different requirements on one assembly
The handrail is the graspable rail your hand runs along and it has a height range; the guard is the barrier that stops a fall on an open side and it has its own height and an opening limit. A railing can satisfy one and fail the other.
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A soda can is about 2 1/2 inches across, so it passes through a guard that meets the rule. The measure that matters is 4 inches: a gap that wide between balusters, anywhere along the guard, does not meet it.
Where Pennsylvania departs from the national number
The maximum riser height in the Pennsylvania Residential Code 2021 is 8 1/4 inches, and no riser in a flight may differ from the smallest by more than 3/8 inch.
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The top and bottom risers are the two that change unevenly in a retread. They are the ones worth measuring twice.
Which version governs where you live
Philadelphia adopts the 2021 IRC as Subcode "R" with its own local amendments; the surrounding Pennsylvania municipalities work from the state Uniform Construction Code, and New Jersey and Delaware adopt on their own schedules.
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Sources and references
- Philadelphia Code, Title 4, Subcode "R", Article R-1.0 (adoption of the 2021 IRC). https://codelibrary.amlegal.com/codes/philadelphia/latest/philadelphia_pa/0-0-0-272229
- Pennsylvania Residential Code 2021, Chapter 3, sections R311.7 and R312.1. https://up.codes/viewer/pennsylvania/irc-2021/chapter/3/building-planning
- International Code Council, International Residential Code. https://codes.iccsafe.org/
Related work
Send a photo and we will tell you what you are looking at
Stair and Railing Code in Philadelphia (IRC 2021) starts with someone reading the house. We quote every job ourselves, with no salesperson in between, and a photo of the floor gets you a straight answer faster than a form does.
