Can You Cement Over Plastic Pipes?

Are you wondering if you can cement over plastic pipes? What is the impact of doing so? We're here to share with you our comprehensive research on these questions.

You can cover plastic pipes with cement, but there are certain limitations to doing so. The cement's weight has an impact on the pressure inside the pipes. So, you should first consider the following about the pipes:

  1. Purpose (or function)
  2. Condition
  3. Location

In this article, we'll discuss some factors to consider should you plan to cement plastic pipes. We'll provide steps on how to do it, as well as discuss related topics. So, let's keep reading!

Can You Cement Over Plastic Pipes?

Workers are water pipes with PVC joints Elbow allows the split to the left or right, which must penetrate concrete walls to make PVC pipe coming out the other side of the building.

Cement has the capacity to make any surface thicker and stronger. But when it comes to applying cement over plastic pipes, although possible, there are things you should consider. 

1. Pipe Purpose (Or Function)

You should know the purpose of the plastic pipes being covered. Most homeowners have plastic pipes for draining the wastewater, while some pipes can drain into the gutter. Also, it's possible that the pipes are for ventilation.

Toilet drainage pipes are quite complicated, as they go beneath the floor and toward the sewer. Most of these pipes are covered in soil or sand, depending on where the house is. If these are the pipes you'll want to cover with cement, then doing so is possible.

On the other hand, gutter pipes running from the roof down to a drain are used for redirecting the rainwater. These pipes are often secured against the base of the exterior wall to prevent unnecessary movements. So, cementing gutter pipes can be beneficial in terms of stability.

In case you're referring to plastic or PVC ventilation pipes, you might want to assess the structure further. The cement can block the airway when the pipes break down, for instance. However, the cement can also keep the ventilation pipes airtight, resulting in more efficient utilization of air throughout the area.

2. Pipes' Conditions

You don't want to apply cement over any pipes with cracks. The cement will just worsen the pipes' condition. Also, check if there are leaks. The cement might act as filler for leaks, but the water or air pressure could penetrate through the pipe and render the cement useless.

It's best to replace the damaged pipe before you proceed to apply cement around it.

3. Pipes' Locations

Identify where the pipes are. You might find some locations difficult to access. For instance, pipes beneath the floor joists might need proper planning before you can apply cement on them. On the other hand, pipes can run along the bathroom corner and through the ceiling. You'll want to be specific about where the pipes are.

What Are the Consequences of Cementing the Pipes?

White plastic sewerage water pipes

It's important to understand that cementing plastic pipes does have an effect. Familiarize yourself with the consequences of doing so with the list below.

Increased Pressure

The cement can increase the pressure inside the pipe because the cement becomes heavier once it gets hard. This might result in faster-flowing air or water. 

Permanent Adhesion

Cement also acts as an adhesive to bond two different surfaces. So, applying it over the pipe can permanently adhere to it.

In case you need to remove the cement, you would smash it with a strong tool like a hammer. However, removing the cement could also damage the pipes.


After some time, it's possible that the pipes will break even if you cover them with cement. When this happens, the broken cement can fall inside the pipes and result in blockages. This is difficult to resolve since it's not easy to access and clear the blocked pipe.

How to Pour Cement Over Plastic Pipes

Red plastic pipes on an insulating layer

Of course, it's good to know the proper steps on how to apply cement over plastic pipes. You'll want to consult a professional if you're uncertain of this task, yet you can see below the steps for pouring cement on ground pipes:

  1. Set up a place outside where you can mix the cement. But if you just need a small amount of cement, simply mix the cement solution into a bucket with water.
  2. Clean the pipes by removing dirt and debris from the immediate area.
  3. Pour and spread the gravel into the base trench to create a drainage layer.
  4. Using construction glue, bond a closet flange on both ends of the pipe. This is to protect the pipes from ground movements.
  5. Apply a silicon caulk along the edges where you'll pour the cement.
  6. Now, mix and stir the cement mixture to achieve good consistency.
  7. Pour the cement mixture over the pipes.
  8. While wearing gloves, get a handful amount of cement mixture and spread it beneath the pipes.
  9. Continue spreading the cement mixture until you cover all the specified pipes.
  10. Let the cement dry, then cover the area with a tarp.
  11. Add another layer of cement on top of the tarp.
  12. Spread the cement evenly, then allow to dry.

How to Use Cement as Adhesive for Ventilation Pipes

You cannot pour the cement mixture on ventilation pipes, specifically if they run along the ceiling and higher areas of the house. But you still can use the concrete mixture to serve as an adhesive for connecting the pipes together.

As part of the preparation, you'll want to use a cement solution for PVC pipes instead of actually mixing the cement yourself.

See this PVC cement on Amazon.

Refer to the steps below:

  1. Get a marker and a ruler or measuring tape.
  2. Measure the length of the existing ventilation pipes where you want to use adhesive.
  3. Mark the pipes to remember the proper alignment.
  4. Carefully detach the pipes.
  5. Now, apply a PVC cement solution around the pipe's mouth.
  6. Connect the pipes together. Make sure to twist them according to the marker to retain alignment.
  7. Put the pipes back on the ventilation system. Check the markings to align the pipes.
  8. You can remove the marker with rubbing alcohol.

To visualize the steps, you can watch a video here:

Can You Detect Water Leaks Behind Cemented Pipes?

Finding leaks behind cemented pipes can be quite difficult to do. But there are ways to identify them. This can prevent you from digging up the cement floor in the wrong location. Check below some signs.

UPVC pipe burst, Can You Cement Over Plastic Pipes?

Unusual Noise

Unusual noise that sounds like rushing water behind the cemented area is a sign of leaking. You can observe the suspected area if the noise stops after a few days. Otherwise, there is a leak.

To hear the noise clearer, you'll want to turn off appliances like a TV or the ventilation fans. You can also do this at night when the house becomes quiet, for instance.

Mold Growth

If the water continues to leak, then it's possible that mold will grow in the area. You'll notice the cemented spot getting darker and harder to clean than the rest of the floor.

Mold growth should be unusual on cemented floors unless the area is exposed to rain or daily activities that involve water. You'll want to clean first the molded area, then come back to see if the mold will grow again.

High Water Bill

If your water bill goes higher than the usual cost, then there might be leaks somewhere in the house. You'll want to check the entire piping system to find the leak. Or else, try calling a plumbing expert to help you detect water leaks behind the cemented areas.

Can You Remove Cement From Inside Drainpipes?

Newly installed pipework system

In case you accidentally poured cement in a drainpipe, there's a way to resolve it. Plumbers could offer you a declogging service to dissolve the cement with a high-pressure water hose and acid. However, you can do the suggestions below in no particular order:

  • Flush the drainpipe with running water until the cement reaches the sewer. This is possible if the cement is still wet and sticky.
  • In case the cement got a bit hard, use a high-pressure water hose to cut it into smaller pieces.
  • If you can access the cemented pipes, consider replacing them.


You can apply cement over plastic pipes. We've provided a list of things to consider before doing so. Also, we shared the steps to pour the cement mixture and discussed other relevant topics.

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