Trained Eye

 
 
 

Drains For Basement Bathroom

Question:

I've been following your column in the Free Press and I have a question you may want to answer. I am considering installing a bathroom in the basement. How would I go about hooking up to the drain lines that are beneath the concrete floor?

Answer:

The addition of a basement bathroom is a very common renovation, but is not a simple or inexpensive endeavour. It is not the type of job I would recommend the average home handyman attempt without the help of a licensed plumber. The difficulty lies in accessing the drain pipes which are embedded beneath the concrete floor and properly installing new fittings and pipes with sufficient slope and design to allow for proper drainage. This always involves breaking up and patching sections of the concrete, which is messy and costly if done professionally.

One way to minimize the expense is for the homeowner to do the concrete removal and disposal themselves. This should be done only after consultation with the licensed plumber that will be redoing the drains. Some investigative work will have to be done beforehand to determine the location of the existing drains and determine suitability. If a bathroom is desired at the opposite end of the basement from the drains, this may not be practical or even possible. A basement bathroom should always be planned in the area closest to the existing drains. This can often easily be determined by the location of the main plumbing drain or stack.

Careful planning is the key to any renovation, but is especially important in this case. Basement ceilings have limited height as well as pipes, ducts, and wires which may be in the way of a planned finished ceiling. All these things have to be taken into consideration before any demolition is begun. Once the plans are finalized and the drain roughly located, then the fun may begin.

First the concrete floor must be removed in the general area of the drain connection as well as the location of the toilet, sink and shower or tub drain (if included). This can often be done with a lot of muscle and a sledgehammer, but a pneumatic hammer will speed thing along considerably. These can be rented at any tool rental outlet or some home centres. Once the concrete (normally 2-4” thick) is removed in the general areas desired, the excavation can begin. The clay soil or pea gravel under the floor must be excavated to expose the drain and allow enough room for the new drains. This backfill should be retained as some of it will be needed after the piping is done.

At this point the plumber will re-enter the scene and plan the actual layout. More concrete may have to be removed at this juncture. The plumber will now cut the existing drains and install the fittings for the new drains. The new drains are usually ABS plastic and can be cut and fit, before disassembly, gluing, and final assembly is done. Extreme care must be taken to ensure there are no joints that will leak now or in the future. This is a primary reason Mr. Falk or other homeowners should not attempt this themselves.

One thing to ensure when adding a basement bathroom is that adequate protection from sewer backup is provided. This is done with the addition of a sewer backup or “backwater” valve installed in the main line. This device will protect the basement fixtures from damage due to any sewer backup. The top of this device will be just above or flush with the finished basement floor and must remain accessible for further inspection or repair.

This is also an excellent time to add a sump pit and pump if one is not present. This can be connected to the floor drain and act as a safety feature. If a storm occurs that is heavy enough to cause sewer backup, the backwater valve will close and the rainwater from the weeping tile will collect in the floor drain. This water will have no where to go but into the basement. The sump pump will pump the rainwater outside, eliminating the possibility of water damage.

Once the drains and sump pit are installed, a municipal building inspector should be called to inspect the new installation. Upon his approval, the holes can be backfilled and the new concrete patching done. At this point the new bathroom walls can be constructed, and the water supply lines put in place. The bathtub or shower is then installed and the shower/tub taps put in place. Another call to the city or town inspector and it’s time to finish the walls. Finally the remaining flooring, ceiling and fixtures can be installed. A heat source as well as an exhaust fan should also be included for proper comfort and ventilation.

 

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