Methods to repair cast iron sewer drains without digging through floors

Excavation for pipe replacement

If you found our website, you’re probably freaked out because your plumber discovered that your cast iron sewer drains have long cracks or holes in them, and they recommend digging up your entire house for a few weeks to replace your cast iron sewer drains the old-fashioned way.

Well forget about that! There are trenchless solutions that you need to know about that the plumbers will not tell you about because they wish to keep your money.

We recently got an inquiry from a gentleman in Dallas Texas who wanted to know what his options were to repair 23 feet of cast iron drain pipe under his floor as opposed to digging it up and replacing it. He already got a quote from a plumber for $10,000, and the price works out to be about $434 per linear foot to do it with this traditional old fashioned way.

So what are the best ways to repair his cast iron drains without the need for excavation through the floor?

Option 1: Trenchless Pipe Lining

Trenchless pipe lining is the most modern method as it involves no excavation or digging whatsoever. In essence, from outside the house or the building where the cleanout exists, the pipe is cleaned using a hydro jetter machine and or a pipe drain snake machine. This removes all the scale and the rust inside the old pipes (and the tree roots to of course if they have grown into the pipe in search of water).

The next step is to use a video inspection camera to measure the length of the pipe and where the incoming connections are. Then the video camera is used to measure the correct length of pipe lining material which is a long fabric polyester tube that is saturated with a self hardening epoxy resin that is exothermic and heats up by itself to 180 degrees Fahrenheit.

Next the lining is installed inside the pipe – The lining is pulled into the pipe using a cable or rope, and it contains a temporary balloon that is inflated to about 15 psi. After a 3-4 hour curing time the pipe lining balloon is pulled out and a brand new rock-hard pipe liner is permanently locked inside the old pipe. And it comes with a 50 year warranty if it is the Perma-Liner brand.

The 2 Most Commonly Used Pipe Lining Technologies Used As Of 2020

Option 2: “pipe bursting”

Old Fashioned Cast Iron Pipe Bursting Trenchless Repair

This is an older pipe renovation technique that pulls a conical head made of very tough metal through the old pipe using a winch.  On the back end of the conical head is a high density polyethylene pipe (HDPE) pipe which is pulled into the void where the old pipe used to be. The problem with this method is that incoming pipe connections are destroyed and they have to be replaced manually by excavating through the floor which has to be replaced with concrete at the end of the process. So the pipe down time is a lot more than just a few hours. The other is problem is that if the soil is extremely hard the pipe bursting head will not pass through the soil very easily and can create problems with the procedure.

So trenchless pipe lining which runs about $150 per linear foot on average is about one-third the price of piped excavation and replacement. It’s by far much more economical and efficient anddoes not displace the tenants who may stay in their homes during the process.

Option 3: replace drain pipe by digging through the floor

This is absolutely the worst possible method because it takes a number of weeks to dig up all the concrete, then dig through the soil which has to be replaced, and then to replace the concrete. Keep in mind that when concrete is we poured it is “green”. That means it needs about 14 days to cure during which time it is excretes calcium carbonate crystals and water which means you’re not able to put carpet or tile over the floor during that period. Also keep in mind that during the excavation and pipe replacement the tenants have already been put out of their residence for a few weeks. Then they have to come back clean up all the aerosol and dust and the e.coli bacteria that have been spread through their entire property.

Also, with excavation, you have to pull permits and schedule pipe inspections, which may or may not pass the first time, in which case you have to make pipe repairs and reschedule for the pipe inspections.