Exactly, and does each state and county really need its own of each code or have to add its own amendments? There are some particular scenarios though where they do: NYC has an extra code related to flooding, California has an earthquake code. Still you'd think a couple states or even a couple countries could all use the same earthquake code.
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We have 3 different codes for wind rating just within our county alone based on the exposure zone. Given some of the peak winds we see it's very much a good thing.
Structural codes are fine by me, the newer energy codes are great too, our new house is so much cheaper to heat/cool than the 70s house we previously owned.
> There are some particular scenarios...
Building considerations are waaaaaay more involved and complicated than you can even begin to imagine.
Well, a lot of the inter-state differences, I've never understood.
For example, Massachusetts changed the stair riser height from 7-3/4" to 8-1/4" (https://up.codes/viewer/massachusetts/irc-2015/chapter/3/bui...).
Why do 49 states (I think) have one height and MA has a different one?
Not saying all the differences don't make sense just a fair amount of them. I'm also not an industry professional (despite staring at these codes all day, I'm usually not actually reading them), so honestly asking here.
I imagine a lot of differences relate to different regional building practices, stemming from both historic trends but also geographic realities. Especially in older areas (but arguably in newer areas, too) you want to permit a greater range of configurations otherwise you risk people abstaining from fixing or replacing unsafe areas, or avoiding permitting altogether. Notably, 8-1/4" is the maximum height--the change allowed more options but people are perfectly free to continue using more common dimensions.
All that really matters is 7-11: the magic ratio for building your own stairs. Perhaps not the most ideal, but the easiest to remember and also trivial to build from common dimensional lumber[1] :)
On a more serious note, what _truly_ matters is consistency of the steps. Interstep deviations are what cause most injuries. After the first or second step, w'ever the rise/run, the brain has already adapted.
[1] 2x6" boards are actually 1.5x5.5". 5.5+1.5==7 and 5.5*2==11. 7-11 is the traditional American rise/run ratio. I think it's mostly coincidental, though, that 2x6 dimensional lumber adds up the way it does.
Great points and very true that this made it more lenient which shouldn't cause problems for out-of-state architects.
Couldn't tell you what the philosophy or justification behind MA's stair riser requirement is.
Have you considered that perhaps the engineers who contributed that change to the MA residential code have done their homework, identified value worth pursuing (whether for safety, building optimization, new material availability, future planning, etc.), and decided it was worth going through what surely isn't a painless ECP process to amend what you've dismissed to be trivial minutae?
I haven't, on second thought, I should have done my homework before taking a stance on that.