Deck handrail post

[DoubleStud]

I must admit, in the residential world, handrail newel post is often overlooked. Somehow the deck is built and engineer never specified anything. I have seen a lot of detail like this below. According to ASCE 4.5.1, a single 200 lb shall be applied in any direction on the top of the rail (or 50 lb/ft). But if this load is pulling on the hand rail instead of pushing, wouldn't you need tension tie at the bottom as well?

 

[Eng16080]

You are technically correct. I’ve never seen a detail with double hold down connections (except my own), but for an inward pulling load, something like that would be required.

I’ve done rather extensive research on this and there are many aspects of this detail that, in my opinion, are often overlooked.

Designing a truly code compliant railing post detail is really difficult. The Simpson detail you reference is called “code-compliant” but it’s really not given the ASCE 7 requirement for the load to be applied in any direction.

I also concluded that in most cases a minimum deck depth of 2x10 or 2x12 is needed for the tension/compression couple not to be excessive.

In any case, the detail above is generally acceptable and meets the standard of care, I guess. Despite the fact that an inward load is neglected, this is generally not going to be a life safety risk, as the railing falling inward normally won’t result is occupants plunging off the side.

 

[phamENG]

Two key points:

1) this is for a GUARD, not a handrail (colloquially interchangeable but defined and treated differently in the code).

2) ASCE 7 is a referenced standard, not the code. For residential decks built in jurisdictions that have adopted the 2021 IRC, the load is only required to be applied in a direction away from the walking surface. It's footnote i of the live load table in R301.

 

[jayrod12]

I tend to try and be rational in understanding that the truly important load application is outward. I fail to see someone accidentally applying a 200 lb point load directly inwards.

 

[skeletron]

NBCC 2020 just updated the wording to include 200lbs outward force, and an inward force that is 50% of the outward force.

 

[Eng16080]

I definitely agree with all the points above, particularly that the inward load is much less a life safety risk.

Where I work, we’re on the 2018 codes and they have a habit of being at least 4 years behind, so I technically can’t take advantage of this code change yet. Still, the standard of care seems to be the detail above or honestly, probably a lot less.

While I have designed and drafted a detail accounting for an inward load, I haven’t deployed it on an actual project yet. I probably will next chance I get. I’m a little curious what kind of feedback I get.

The most likely scenario resulting in this loading that I can think of would be with a hammock setup inside the deck.

 

[rb1957]

my own admittedly ignorant opinion is this looks like over-kill How much force can a simple washer and nut resist (without the tension clips) ? Agreed, if the consequences of failure (of an outward load) would be fatal then more design effort is worth it. But then you should consider (shouldn't you ?) more failure modes ... rotten wood, corroded fasteners, ... a typical Engineering thing ... once you look under a rock you reveal of whole mine shaft of problems !

"Hoffen wir mal, dass alles gut geht !"
General Paulus, Nov 1942, outside Stalingrad after the launch of Operation Uranus.