Trained Eye

 
 
 

Plastic Supply Piping

Question:

After having our house built approximately 1 1/2 years ago, the basement floor moved. It is my understanding that this is normal since they call it a floating concrete floor. Unfortunately, the copper pipes from the hot water tank were placed tightly against the roof and subsequently buckled. Fortunately, the house was under warranty and the builders were very prompt at replacing the copper pipes with flexible plastic pipes. My question is, are plastic water lines as long lasting and as durable as copper pipes? I plan to plumb a basement bathroom with plastic pipes due to the risk of the floor shifting again.

Answer:

Some movement of a basement concrete floor slab is to be expected in the first few years after a home is built due to disturbance and redistribution of the ground when the hole for a foundation is dug. This can be minimised by installation and compaction of various types of gravel or stone. The gravel helps with drainage of moisture as well as gives a more stable base for the floor concrete. If the concrete is pored too thin or is uneven due to plumbing pipes and other structures in the floor it may crack unevenly and be subject to increased heaving pressure. Making sure the drainage system around the house is working along with the sump pump is important. This will minimize hydrostatic pressure from the soil.

I am glad to hear that you had the situation of your buckling copper supply pipes fixed before there was serious water damage done. The plastic pipes should allow for an added degree of flexibility if they are properly installed. Most of the plastic supply piping used today is good quality, although copper is still considered to be the highest quality. There have been well-documented problems with some types of plastic piping and you should make sure you have a type installed that is suitable for your house and needs.

The majority of problems that have occurred with plastic piping have been with Polybutylene (Poly-B) piping and connections. Most of the problems have occurred at the joints and fittings or crimp rings. Older aluminum crimp rings have been problematic. Properly installed copper crimp rings have had better success.

Some problems with the actual piping have been seen. This is thought to be due to a reaction between the Chlorine in municipal water supplies and the piping. This is more of a problem in the U. S. , but there have been instances in Canada . Some plumbing codes have disallowed the use of Polybutylene for interior water distribution systems and it is not stocked at many supply stores.

The Poly-B used inside residential buildings is easily identified by its grey colour. If this is installed in a home, the piping should be monitored for leaks and replaced as soon as a problem occurs.

The supply piping installed in the newer home in question is likely PVC, CPVC or other another polymer. PVC and CPVC piping may be white or cream coloured, is rigid, and the joints are glued or solvent welded together. Much of this type of piping has been in use since the 1960’s and has a record of good performance. There are more modern types of plastic piping that are being use and may be whitish or almost clear in appearance. These are more flexible and are often joined with crimp rings similar to Poly-B. This is likely what has been installed for the repair mentioned above.

Whatever type of supply piping you decide upon, you should check with local licensed plumbing contractors and the zoning or building inspection division in your area for details on what is acceptable for use in your particular application.

 

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