The requirement for residential handrails is not a max radius of 2" (which would be a diameter of 4") . The IRC limits handgrip design to two kinds: Type I and Type II. To put it simply, Type I is round (or almost round) and is limited to a max. diameter of 2" or a maximum perimeter dimension of 6 1/4" and a maximum cross-section dimension of 2 1/4". Type II is a non-round handrail that exceeds 6 1/4" in perimeter dim. and has slight finger recesses along the sides. It is also limited to a maximum overall width of 2 3/4". You will find that these dimensions match the most commonly available wood handrails. A 3" diameter antique railing would not meet the requirements of a Type I handrail but if it was no wider than 2 3/4" (or close to it) and it was possible to get your fingers around the upper part of it, the building inspector is within his authority to accept it as a Type II, if he thinks it serves the intended purpose of the IRC or is equivalent to its provisions. As for the flat 2x4/2x6 handrails, assuming the stairs are high enough to require a handrail (4 or more steps), and were built after the building code was adopted, they should have been 1x4's trimmed with radiused edges to be no more than 2 3/4" wide overall in order to meet the Type II grip requirements. It would be easy to add a standard Type II wood handrail on top of the flat boards. As for termination of handrails, the IRC requires a residential handrail to extend to the last riser but it also provides two exceptions, one of which allows a "volute, turnout, starting easing or starting newel ... over the lowest tread". This allows a building inspector to accept a major deviation for the distance of the last tread, even the absence of the handrail if he believes it serves the intended purpose of the IRC or is equivalent to its provisions. Without this exception many traditional stairs could not be built. If there is a handrail on the other side of the stair, one of the handrail is not required so the inspector can accept almost anything. There would be no reason for a building inspector to comment on things he has decided to accept so I don't understand why you mention that. The inspector also relies on the design documents to indicate how many controlled elements (like windows) meet the building/energy codes. Not everything in a house has it's specification standards written on it. I mention all of this trivia only to demonstrate that building codes are not simple or interpreted in only one way as is so commonly assumed by homeowners and even builders. The authority of the inspector to accept alternative design solutions is also not commonly understood. In the end, it is not a building official's responsibility to make sure you meet the requirements of the building code; that is your responsibility alone, even if you privately assign that responsibility by contract to design professionals and/or builders.

Hi, You understood my second option perfectly. The first option just has the short return piece meeting the newel while rotated or canted at the angle of the staircase. This is easiest as it does away with the transition, and most builder-grade new construction defaults to this simpler alternative. Just remember that your horizontal balcony or landing rail must be at 36-38", but the stair handrail must be at 32=34" above the nosing of the treads. This creates a great disparity, and it is very possible that the square part of your newel (assuming that it has a turned section in the middle) will not be capable of catching both of these rail heights. That's what goosenecks are for. The gooseneck raises the terminus of the railing to the very same height above the landing as the horizontal rail, thereby creating a visual unity to the whole assembly. It's not that a gooseneck is mandated by code, it just looks better, and lets you use a newel with a smaller square section. (newels are made with as longer and shorter square sections.) Just make sure you understand that the stair rail must be within the 32-34" range. Casey

Lyndee Lee: Center city Philadelphia is filled with old, old houses (well, old by American standards--pre-Revolution), some quite small with very small winder staircases. In some of them there is a vertical grab bar as you describe, but my favorite solution is a very thick rope. It just suits the age of the houses. And, if you look carefully, above the front door, you will sometimes see a 'mattress slot'. The floor above is removable between two beams so that mattresses could be lifted up there; they can't go around the winder staircase.

thanks for comments! Our contractor said all of the railing has to be 42” according to the code. However, found this in the CA residential building code 2019 manual: R312.1.2 Height Required guards at open-sided walking surfaces, including stairs, porches, balconies or landings, shall be not less than 42 inches (1067 mm) in height as measured vertically above the adjacent walking surface or the line connecting the nosings. Exceptions: Where the top of the guard serves as a handrail on the open sides of stairs, the top of the guard shall be not less than 34 inches (864 mm) and not more than 38 inches (965 mm) as measured vertically from a line connecting the nosings. We’ll check with the city.