Thread: Post Required

We are trying to get our stair railing manufactured for our new house. One of the railing guys said we would need a center post because the run is longer than 8'. I wasn't aware of any specific post spacing requirements as long as the side force parameters were met. At a 10 foot run, that should not be a problem with a steel railing anchored at both corners. I did not see any requirement in the IRC. Are any of you aware of a post requirement for the guard rail?

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Originally Posted by Jim Robinson

We are trying to get our stair railing manufactured for our new house. One of the railing guys said we would need a center post because the run is longer than 8'. I wasn't aware of any specific post spacing requirements as long as the side force parameters were met. At a 10 foot run, that should not be a problem with a steel railing anchored at both corners. I did not see any requirement in the IRC. Are any of you aware of a post requirement for the guard rail?

Hi Jim,

Is this a handrail, guardrail or combination?

I do not know of any specific maximum unsupported length. You are correct, both the handrail and guardrail must resist a 200 lb point load (IRC Table 301.5), but I don't see any maximum allowed unsupported length or maximum amount of allowed deflection.

However, at 10', there is going to be some deflection in 1-1/4" tubing (if handrail) and the fabricator might have other guidelines or standards (ASTM or ANSI, for example) that they are using as well. If you really don't want the additional post, I would ask the fabricator where that requirement is and see if there is any way around (thicker-walled tubing, or increasing the diameter, for example).

To expand on things Gunnar addressed.

Originally Posted by Gunnar Alquist

You are correct, both the handrail and guardrail must resist a 200 lb point load (IRC Table 301.5), but I don't see any maximum allowed unsupported length or maximum amount of allowed deflection.

That 200 pound load is:

- handrail: in any direction

- top rail of guard: horizontally

- top rail of guard if also serving as a handrail: in any direction and horizontally (needs to resist both, in case someone decides that "any direction" does not include horizontally)

- guard infill (whatever is restricting the space below the top of the guard so as to not pass the sphere: 50 pounds sq foot horizontally

However, at 10', there is going to be some deflection in 1-1/4" tubing (if handrail) and the fabricator might have other guidelines or standards (ASTM or ANSI, for example) that they are using as well. If you really don't want the additional post, I would ask the fabricator where that requirement is and see if there is any way around (thicker-walled tubing, or increasing the diameter, for example).

Using a heavier schedule tube (thicker wall) would provide for a greater span end to end.

Originally Posted by Jim Robinson

One of the railing guys said we would need a center post because the run is longer than 8'.
.
At a 10 foot run, that should not be a problem with a steel railing anchored at both corners. I did not see any requirement in the IRC.

Two things come to mind:

- "steel railing anchored at both corners" ... where will the intermediate supports be for the handrail, or is it the top rail, or both?

- If handrail, then the handrail will have intermediate supports on the guard rail infill.

- If top rail, them the infill will likely provide some intermediate support for the top rail.

- If both top rail and handrail, see top rail comment above.

What is the infill of the guard?

And if they put in an intermediate newel post, they need to make sure that does not interfere with the handrail as the handrail needs to be continuous.

This is guard rail only across the top of the stairway opening. 1.50" steel tube top and bottom, with 3/8" steel balusters vertically. Okay, that was what I thought about the requirement. The guy was kind of all over the place for someone who builds railings as part of his job.

Okay, got it.

It's not stair railing, not going up the side of the stairs.

It's a guard (guardrail by some) along the open side of a walking surface with greater than 30" down to the lower surface below (like at a deck, balcony, stair opening, etc).

No handrail is required, just a top rail.