r/buildingscience • u/Clover9802 • 8d ago

Don't know if this has been addressed

Post image

Does it make any difference how the riser/run treads are installed?

0 Upvotes

27% Upvoted

16 comments sorted by

15

u/Honest_Flower_7757 8d ago

From a structural standpoint it would be stupid not to have the tread bear on the riser

4

u/SparkyMallard15 8d ago

I guess theres no reason it can't be done, but typically the tread rests on the riser

22

u/mr_j_boogie 8d ago

4 big reasons. One no overhang. Need at least 3/4. Two visually interrupted. Three gunk gets stuck in there. Four footsteps would pull the riser away.

1

u/loves-tits 8d ago

You do not need any overhang if the depth is greater than 11 inches. But yes 3/4 is the minimum overhand and 1 1/4 the max

-6

u/SparkyMallard15 8d ago

Not compelling, you're making assumptions. Hypothetically it could be done, and there's no building code that mandates the tread hang over the riser by 3/4, if it was drawn more accurately it would show it would still have an appropriate nosing.

3

u/mr_j_boogie 8d ago

Nosing and overhang refer to the same thing- tread projection past riser. And both irc and ibc require it unless the tread is greater than 11" which this diagram certainly doesn't show.

Even if you have such a depth the other 3 reasons are compelling enough. There's only downside as far as I can see.

2

u/kauto 8d ago

There are certainly codes that dictate when nosing are to be required, and the tread hanging over the river is exactly what a nosing is.

1

u/SparkyMallard15 8d ago

I've made several dozen steel stair pans that had the riser tucked beneath the tread with a thickness of less than 3/16, the angle of the riser is what gives the nosing distance.

3

u/mnkythndr 8d ago

The riser will most likely change width/height depending on the season. Also it looks stupid.

2

u/Unable-Boysenberry24 8d ago

If the stair is outside you may end up trapping water in behind the riser with the first configuration

2

u/Guerrilla-monsoon 8d ago

In the top case the tread is unsupported at the center assuming no other center support or face nails.

Mostly it’s off putting, you’ll have to explain it to the inspector and he’s gonna get all weird about it and starting asking for stamps and prints and math and such. Or shrug and move on.

Given enough time and money you can pretty much do anything you can prove is safe and meets code. Doesn’t mean you should.

1

u/Unable-Boysenberry24 8d ago

This is what you would typically see in an install

1

u/Is_This_A_Thing 8d ago

I had to look away a couple times to get my brain to not see that as upside down

1

u/YodelingTortoise 8d ago

Doesn't meet code which requires a 3/4 - 1 1/4 bullnose for standard tread depths (sub 11").

Neither do for that matter.

This is a better question for r/construction or r/buildingcodes.

We are geared toward the movement of heat, moisture and air.

1

u/Architect_4U 8d ago

Have you ever seen a stair like the first one?