Figuring the water level only goes to 6" high, which is very possible, the weight on this roof is over 5,600 pounds which is only 675 gallons of water.

Imagine this pouring in on the computers. What a mess huh?

Now suppose we install a scupper no more then 4" above this roof located as close to this drain as possible, as this is the lowest point, and we run an outside copper leader pipe down to the next set back over that drain and the same for each set back. NOW what is the worst that can happen if one or even two drains fail?

The building owner looked over to the engineer who just gave me a look closed his attache case and left.

The architect was a little less subtle but he also left the room.

Now it was just me, the building manager, the building owners and the building superintendent.

I finally said "The reason this had to be brought up is, in this city the LMP is responsible for the plumbing and that is why we file the jobs and we are allowed to self inspect as the accountability, and rightfully so, falls on us not the engineer or designer BUT on the installer."

I then said "I have no problem submitting my own specifications per drains and sizing them for a controlled flow, if needed, not to over load the system BUT it was going to cost someone major bucks."

The building owner said "Hey I just saved myself the expense of the other two guys so it still has to be cheaper."

What we normally do, as professionals, we discuss options long before work progresses. BUT in this case the engineer and his fellow "professional" wouldn't even discuss options with me.

For example I contact the roofing contractor and ask "what type of roof membrane are you installing"?

Are we going with tapered insulation or auxiliary drains where ponding is a problem?

Is this a built up roof or single ply?

Is there insulation and is this an upside down roof.

Would it be better to use a double flange roof drain with double lead flashing.

Are we using gravel or river bed rock for ballast?

What type of pitch are we using as this is how I size the leader lines?

How many ply of felt membrane are there going to be laid by my gravel stop.

Are these leader lines going to connect to a combined system where we have to either GPM or sq. feet of drainage by interpolation?

What materials are connecting to Lead, Cast Iron, no hub cast Iron, galvanized, etc.?

On a promenade deck we allow for two times the effective drain opening as we know the flat type of strainer can get blocked up very quickly.

Can we use a bronze dome in lieu of Cast iron?

Can one storm trap serve the entire storm system?

Meeting prior to specifications are written is always a great idea.

Having a clause or equal is also a must in case one manufacturer cant fill the order in a timely manor.

Working right along side a professional roofing contractor is one of the best insurance policies possible.

Being flexible with design and having an open dialog is very important.