How to insulate underground water pipes

 Installation of non-watertight insulation

Step 1 - Installing gravel and plastic sheeting

First, place 7.5 cm of gravel at the bottom of a 75 cm trench. Then, line the trench with heavy plastic sheeting.

Step 2 - Install foam board insulation

Cut the rigid foam insulation into 30 cm wide strips. Lay several of these strips, to a depth of 10 cm, over the plastic sheeting. Next, lay the water pipes on top of the insulation. Add insulation, again to a depth of 10 cm, on both sides of the water pipes. 

Step 3 - Tape the sheet

Fold the plastic sheeting so that the sides completely cover the insulation and tape it down. Next, use another 60 cm wide piece of plastic sheeting and wrap it around the top of this package. Tape the edges along the sides of the insulated package to prevent moisture from penetrating it.

Step 4 - Filling the trench with soil

Finally, fill the trench with soil. Although this method of insulation works well, remember that if water penetrates the trench, it will seep in and make the insulation damp and ineffective.

Installing watertight insulation

Step 1 - Coating the pipes

To create water-tight insulation for water pipes, the pipes must be inside a larger pipe. Use a 22 cm concrete or plastic sewer pipe to cover the smaller water pipes.

Step 2 - Obtaining polystyrene

Many people give Styrofoam as a gift, so before you buy it, it is a good idea to find out from neighbours or online advertisements. You will need several pieces large enough to cut, so that they fit into the sewer pipe like discs, with the centres cut to hold the water pipes.

Step 3 - Installing the polystyrene

Place a polystyrene foam disc at the end of the sewer pipe and run the water pipe through it. 

By alternating small pieces and discs in this way along the entire length of the sewer pipe, you will insulate the water pipes and support them. This method is completely waterproof and effective.

Call the Emergency Plumber in Leeds. We are available around the clock.