Who trains the new design engineers and architects in roof drainage?
Having just completed 37 drains on a large building with lots of setbacks. What I am curious about is who trains the new design engineers and architects in roof drainage? After my 3rd day on this job I asked for a meeting with not only the designing engineer but also the building owner and the architect.
I thought I at least owed these folks an explanation as to why I was going to hit the owner with extras on every single set back plus the majority of the other drain installations that were specified would also cause an increase in cost
At this meeting I mentioned that each set back had only one drain and not every drain was the same size outlet.
What I did find was several layers of roofing membrane had been installed over the last 50 years and each time a new layer was put on the drain was sleeved thus decreasing the internal pipe diameter.
I also stated that to leave one drain on these set backs was not only asinine but borderline criminal.
At this point the designing engineer jumped in saying that it is not even an option to install a second drain PLUS why have redundancy into the same pipe?
Not to be out done the architect then opened his mouth saying it is IMPOSSIBLE to install another drain on the 12th floor, 14th floor 16th and 18th floor set backs as the ceilings below was mirrored and some of the set back roofs were over computer rooms so access from below was impossible with all the duct work for the environmental controls.
I said OK then since these drains are "impossible" I will just have to charge double for each of these impossible drains to guarantee integrity of the roof on these set backs.
The engineer, now visibly upset, said, "Why are you so concerned about something you should not even be discussing with us and especially with the building owners present."
Having one drain on this slab that is only 2" is ludicrous as when this drain does block up, say on a weekend, during a heavy rain consider this.
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 3" 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 attaché case and left.
The architect was a little less subtle but he also left the room.
Now it was just the building manager, the building owners and the building superintendent and myself
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 riverbed rock for ballast?
How much pitch are we using, as this is how I size the leader lines? (more pitch can require larger lines)
How many ply of felt membrane are there going to be laid by my combination retaining ring / 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, XH 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.
I said "Sir, with all due respect, the Master Plumber has the final responsibility of insuring the plumbing/storm drainage system is installed, not only according to local code, but also so as not to allow a dangerous condition to exist due to faulty design."
With that the voices got extremely loud when the owner said "OK, hot shot, what is the problem as you see it?"
I went on to explain that one set back was 12 ft x 15 ft with a 4 ft parapet with a 2" existing drain that I had replaced BUT the piping below this drain was galvanized.
Even though I did take the precaution of snaking out these original pipes I know the inside is still reduced from years and years of accumulation of pitch (bitumen) and some gravel plus some internal corrosion, all these factors have to be taken into consideration for people who do take this profession seriously
Sylvan LMP (Licensed Master Plumber)
"Plumbers Protect The Health Of The World.