The last chance drain


The importance of floor drains and their proper utilization has yet to be fully realized

This commercial kitchen floor drain is pre-set through core slab before floor tiles are laid.

By Mark E. Evans

“If you want to set your tools down in a dry part of the basement put them by the floor drain.”

I learned this lesson early and still find it helpful today. However, someone should let the concrete guys know that water goes downhill.

Too often they slope the floor up to the floor drain rough-in pipe that is stubbed up and capped. This makes that area the high-point and the only place in the room without a puddle.

This is usually a residential basement problem as commercial floor drains are typically set to proper height before the floor is poured.

It’s not only the concrete guys who don’t realize that their work impacts the mechanical systems’ effectiveness, it’s also the basement finishers that put their flooring right over the drain and in many cases, right over the building clean out as well. Good luck trying to use or service those drains ever again. When I see this “kwality” of work in a finished basement, I automatically assume the worst for all the mechanical “up-grades.” When the inevitable flood occurs, insurance companies are more often denying claims because the work was sub-par and unprofessionally installed. My information is that it’s the number one insurance claim.

The requirement for good workmanship may have been taken out of our code book, but in the cut-throat world of finance, it’s alive and well.

Ceiling view of a suspended P-trap serving four gang-trapped floor drains in a commercial setting. The whole system is full of grease and does not work, making for a very unsanitary food preparation environment.

A little knowledge is dangerous

The importance of floor drains and their proper installation have yet to be fully realized by associate trades, the general public and even mechanical technicians. I believe that as the insurance stranglehold tightens on our industry, builders will be held accountable for improper installation, so understanding and correcting any problem is critical. I know those insurance companies have much deeper pockets than I do so I do my best to avoid any conflict with them. In fact, I have found a kind of business niche working with them. There’s money to be made in the restoration business and I’m finding more work as a mechanical consultant. I’m being contracted for professional advice after negative water related incidents and also before to pro-actively assess potential future problems. I rather enjoy that type of work. It gives me a chance to see just how dangerous a little knowledge can be and increases my respect for the trade and the true professionals that practice it.

We can’t stop the do-it-yourselfer from connecting pipe and fittings together and calling it “plumbing,” but we can stop using certain practices within our trade that although code approved, have proved to be troublesome.

One example is the typical method of roughing in the laundry in the basement where the kitchen sink is directly above on the main floor. The drains are tied together and connected to the wet vent for the floor drain or a branch drain.

The combination of lint from the washing machine and grease from the kitchen above wreaks havoc on the system.

Many times, these plumbing groups are served by a common branch drain that includes a bathroom group or two.

Over time, the branch drain becomes coated with lint/grease sludge which backs up the line spewing raw sewage into the basement via the floor drain. I’ve been to many service calls where the main floor is rented out as a separate unit and those tenants are unaware that they are creating a “Hazardous Materials” environment in the basement. Each flush from above pours out the easiest outlet it can find, usually the floor drain. I’ve witnessed volcano like ejections coming from kitchen sinks, bathroom sinks, bathtubs and showers, but the time I saw a geyser coming out o fa lower level toilet was most memorable. What a show!

Some commercial floor drains are also hub-drains used to drain fixtures or appliances.

Solving the problem

Even if everyone stops using the fixtures during the crisis, the condensate drains, softener discharge, reverse osmosis units and a host of other “non-participatory” systems are still actively trying to use the blocked drain.

Solving this problem entails making additions to existing requirements, including:

The minimum size of every buried drain should be two inches. Kitchen drains should be two-inches minimum and connect independently to a viable drain of at least one trade size larger diameter.

An accessible clean-out should be installed in the vent pipe of the kitchen sink and laundry. This will allow access for rodding and/or the insertion of a blow-up test plug to create a closed space downstream so positive

pressure can be applied to the drain. I have blown out grease blockages using this method but had to open the wall and modify the vent to do so.

Lint guards should be mandatory for every washing machine waste.

“Solutions” is really just a figure of speech in this context because there is no system so “foolproof ” that it could stop the most determined fool. I know it’s true because I’ve done a lot of service work in student housing. Still, we have to try.

I don’t remember this being such a big problem in the past, but grease blockages are becoming a real common thing in my service area. No doubt the advancing age of the systems contributes to the problem, but I think the dynamic of food preparation, consumption and waste removal has changed.

The answer to the question of which drain is the most important may vary depending on who and when the question is asked, but aside from personal emergencies, I think it’s the floor drain. It’s the last chance in any building to use gravity to protect against a destructive sure thing. Water will always go to the bottom and there will always be the threat of water from somewhere.

Whether from a plumbing system leak, an overflowing bathtub, spring run-off seeping through a foundation crack or a million other sources, there must be a system in place for removing flood water from the living space.

If it’s the system that’s causing the flooding, then the problem is ours and we have to change the design or pay the price.


Comments are closed.