What defines a "walking surface" at a roof deck?

[nealderidder]

I'm putting a new roof deck on an existing 4 story building. I'd like to keep the guardrails to a minimum to keep the views unobstructed.

Guards are required (CBC 1015) along open sided walking surfaces within 36" horizontally to the open side.

On a roof deck would you consider the finished deck the boundary of the walking surface? One could always go rogue and step off the deck and down on to the roof. If I add a rail to the deck does that suffice to determine the boundary?

Attached are two scenarios. "A" shows the walking surface defined by a rail. It's more than 36" from the open side (four stories down).

"B" shows the walking surface defined only by the finished deck with no rail that is more than 36" from the open side.

Unfortunately my parapet is under 42" for a good portion of the roof, down to a minimum of about 24" high.

Would you buy either one of these proposals?

 

[steveray]

I would call the deck edge the walking surface....Might be an owner liability, but not mine....

 

[RLGA]

To preserve the roof warranty, I would want to keep occupants off of the roof membrane, so my opinion would be that 'A' is the best option.

 

[e hilton]

Your sketch isn’t quite to scale, but it looks like the deck surface is about 12” above the roof. Wouldn’t you need to add a step? I agree with rlga ... keep foot traffic off the roof surface.

 

[steveray]

If you add a step, now the roof is a walking surface and guards would apply.....12" is not a legal riser height and therefore the roof cannot possibly be a walking surface requiring guards...

 

[e hilton]

Your sketch isn’t quite to scale, but it looks like the deck surface is about 12” above the roof. Wouldn’t you need to add a step? I agree with rlga ... keep foot traffic off the roof surface.

Oops ... i see a dimension on the top sketch ... 16” from the deck to the roof. It’s looking more like the best place for the guard rails is up on the deck.

 

[nealderidder]

If you add a step, now the roof is a walking surface and guards would apply.....12" is not a legal riser height and therefore the roof cannot possibly be a walking surface requiring guards...

Agreed, I'm not planning to add a step to the roof.

 

[nealderidder]

To preserve the roof warranty, I would want to keep occupants off of the roof membrane, so my opinion would be that 'A' is the best option.

Ron - agreed it's a good idea to keep folks off the roof but is the rail really required?

 

[Paul Sweet]

A rail should be provided to keep people from accidentally stepping off the edge.

Although IBC & ADASAD don't directly address this, a 36" high rail with edge protection complying with ADASAD 405.9.1 or 2 should be adequate for this purpose. You don't need a guard.

 

[sergoodo]

I'm not drinkin on that deck without rails.