How To Work With PVC Pipes

Knowing how to use PVC pipes can come in handy for a do-it-yourself (DIY) homeowner. Polyvinyl chloride (PVC) is the standard for drain, waste, and vent piping in homes and has been since the late 1960s. Its versatility, durability, and easy usage make it a popular choice for many plumbing projects. Below, we explore the basics to know about PVC pipes, from understanding different sizes and fittings to proper cutting and assembly techniques. This Old House plumbing and heating contractor Richard Trethewey demonstrates common techniques for working with PVC pipes in the video above.

PVC Pipe Sizes 

PVC pipes come in various sizes. These are the most common sizes used in households:

• 3-inch pipes: Typically used for toilet drains
• 2-inch pipes: Commonly used for shower drains
• 1.5-inch pipes: Often used for kitchen sink and lavatory drains

In plumbing, the size refers to the pipe’s inside diameter, unlike other construction measurements that use outside dimensions.

Types of PVC Fittings

PVC fittings connect pipes and create the necessary angles and transitions in your plumbing system. Common fittings include the following:

• Couplings: Used to join two pieces of pipe with no angling
• Elbows: Available in various angles (22, 45, 60, and 90 degrees)
• Street fittings: Designed for smoother transitions and better flow

When selecting fittings, assess the flow of water and potential clog points. For example, a standard 90-degree elbow might create a sharp turn that could lead to clogs, while a street fitting with a gentler sweep can provide better drainage.

Tools and Materials for Working With PVC Pipes

To easily work with PVC pipes, you’ll need the following tools and materials:

• Deburring tool
• Felt-tip marker
• PVC cement
• PVC pipe saw or handsaw
• PVC primer
• Safety glasses
• Tape measure
• Work gloves

These items help you cut, clean, and assemble PVC pipes efficiently and safely.

Cutting and Preparing PVC Pipes

The way to a leak-free connection is precise cutting and preparation. Follow these steps to cut and prepare your pipes:

1. Measure and mark: Use a tape measure to determine the required length and mark the cutting point with a felt-tip marker.
2. Cut the pipe: Use a PVC pipe saw or handsaw to make a clean, straight cut at the marked point.
3. Deburr the pipe: Use a deburring tool to remove any roughness or sharp edges from the inside of the cut pipe.
4. Clean the pipe end: Wipe the cut end of the pipe clean to remove any debris or shavings.

Assembling PVC Pipes and Fittings

The assembly process for PVC pipes involves a two-part system of primer and cement. This method creates a strong, watertight seal between pipes and fittings. Here’s how to properly assemble the PVC components:

1. Dry-fit the assembly: Before applying any adhesives, test-fit your pipes and fittings to ensure proper alignment.
2. Mark the assembly: Use a felt-tip marker to draw alignment lines across the pipe and fitting joints.
3. Apply primer: Use PVC primer to clean and soften both the pipe end and the inside of the fitting. The primer removes any surface contaminants and prepares the surfaces for bonding.
4. Apply cement: Quickly apply PVC cement to both the pipe end and the inside of the fitting.
5. Assemble immediately: Push the pipe into the fitting, making sure to align the marks you made earlier.
6. Hold for three seconds: Maintain pressure on the joint for at least three seconds to ensure a proper bond.

Remember that PVC cement sets quickly, so work efficiently during assembly.

Tips for a Secure Assembly

Achieving a watertight seal requires attention to detail and good technique. Follow these tips to ensure successful PVC pipe assemblies:

• Always use the appropriate amount of cement. Too little can result in weak joints, while too much can cause the cement to pool inside the pipe and cause clogs.
• Secure the joint by twisting the pipe a quarter turn as you insert it into the fitting. This action helps spread the cement evenly.
• Allow the assembly to cure for at least 24 hours before subjecting it to pressure. This ensures that the bond has fully set and will hold up under use.

Transitioning Between PVC and Other Materials

In many plumbing projects, especially renovations, you may need to connect PVC pipes to existing plumbing made of different materials. The transition sections below include tips for working with various materials and ensuring strong connections.

Connecting to Threaded Pipes

For connecting PVC to threaded pipes, such as galvanized steel, use a threaded adapter fitting that has PVC on one end and threads on the other. Apply Teflon tape to the threaded portion. Screw the adapter into the threaded pipe. Connect your PVC pipe to the adapter using the standard PVC assembly method.

Connecting to Nonthreaded Pipes

For connecting PVC to nonthreaded pipes, such as copper or cast iron, use a neoprene gasket with a stainless steel clamp for a secure connection. For cast iron pipes with a hub, use a special adapter called a man-off sleeve along with oakum and lead for a professional-grade seal.

Transition Techniques for Brass and Copper Pipes

• Use brass to PVC threaded transitions: Brass can have threaded connections which can screw onto PVC adapters. Ensure to use threaded brass adapters along with Teflon tape for a tight seal.
• Use mechanical couplings: These can connect PVC to copper pipes without the need for soldering, ensuring a secure join with stainless steel clamps.
• Insert bushings when needed: In situations where pipe sizes are transitioning, using reducing bushings can help in achieving a proper size match.

Always ensure that your transitions are appropriate for the specific materials and pressure requirements of your plumbing system.

Safety Considerations When Working With PVC Pipes

When working with PVC pipes and related materials, follow these safety guidelines:

• Wear safety glasses to protect your eyes from debris and chemicals.
• Use work gloves to protect your hands from sharp edges and chemical exposure.
• Work in a well-ventilated area, as PVC primer and cement have strong odors and can be harmful if inhaled in large quantities.
• Follow manufacturer instructions for proper handling and disposal of chemicals.
• Keep PVC primer and cement away from heat sources and open flames, as they are flammable.

Expanding Your PVC Installation Skills

Mastering the basics of working with PVC opens the door to a range of home improvement and DIY projects. Beyond plumbing, PVC pipes can be used to build various practical and fun structures, such as garden trellises, outdoor play structures, and shelving units. The versatility of PVC allows you to create custom solutions for your home and garden.

Maintenance and Troubleshooting PVC Pipe Installations

Maintaining your PVC installations ensures longevity and reliability. Here are a few tips:

• Regularly inspect joints for signs of wear or damage.
• Use a plunger or plumber’s snake to clear minor clogs in PVC drains without using harsh chemicals that could damage the pipes.
• Replace cracked or compromised sections promptly to prevent leaks and water damage.

By staying proactive with maintenance, you can avoid larger plumbing issues down the line.