What are channel drains? Everything you need to know, plus how to install a channel drain

Also known as a trench drain or a linear drainage channel, a channel drain is an essential product for preventing drainage and rainwater issues on non-porous surfaces. Typically found on driveways, patios and other paved surfaces which cannot absorb rainwater, a concrete or plastic drainage channel helps prevent flooding and ‘ponding’ of water, making it a great solution for water management around your home or property. 

If you’re new to channel drains and aren’t sure how to choose or install  them, we’ve put together this guide to help you get to grips with it all.

Read on for the full article, or click on the section you need to get started:

  1. What are channel drains?
  2. Types of channel drains and channel grates
  3. Checking the weight load of your linear drainage channel
  4. How to install a drainage channel

What are channel drains?

A channel drain aims to manage and direct surface water that falls on non-porous surfaces, ensuring the water is directed to an appropriate main drainage site (like a drainage pipe). Most linear drainage channel products, as the name suggests, are designed as straight, narrow, U-shaped channels, and they are usually installed just below ground level with a flat drainage channel grate covering them. 

Channel drains are usually found in high traffic areas, anywhere where rainwater cannot be absorbed naturally into the ground. The most popular locations include driveways, garage thresholds, pathways, patios and large, flat expanses of solid paving. Without a channel drainage system, you may find that rainwater tends to pool or ‘pond’ in large quantities on your patio or drive, which can become problematic in very heavy downpours and can even cause water damage to your paving. A linear drainage channel allows the water to drain safely away from flat surfaces, keeping your property free from unsightly, damaging and potentially dangerous standing water.

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Types of channel drains and channel grates

Linear drainage channels come in various materials and types, but the two most common types used around domestic properties are concrete and plastic drainage channel designs. Each material type carries benefits and purposes, so here’s a quick overview of these two main types of channel drain:

Plastic channel drain

By far the most commonly used type of linear channel drainage for domestic homes, a plastic channel drain is made of lightweight polypropylene, making it durable and easy to install. In fact, this material type is so popular that all of the linear channel drains we currently sell here at Build & Plumb are manufactured from plastic. Because they’re so lightweight, a plastic channel drain is really easy to lift and transport, which adds to the ease of installation. 

Polypropylene is also nice and strong, making it sturdy enough for weight-bearing in high traffic areas, and It’s also chemical resistant, so you don’t need to worry about the channel breaking down if you’re using garden chemicals like fertilisers or weed killers. All in all, a plastic channel drain makes the perfect choice for installing at home on any driveway, garden or patio.

Concrete channel drain

A channel drain made from high-strength concrete materials is designed to be extra sturdy for coping with chemicals and higher weight loads. These are less commonly used for domestic landscaping, as most home properties don’t require channel drains to cope with excessive chemicals or weight loads any heavier than foot traffic and occasional car traffic. However, you can use a concrete channel drain at home if you wish.  

Types of drainage channel grate

The channel grate is the flat, slotted section that sits level with the ground over the top of your channel drain and allows water from your driveway or patio to drain into the channel. It  also prevents the channel from becoming clogged with debris like sticks and leaves. 

You can find drainage channel grate designs in various materials, with the most common types including plastic, aluminium and stainless steel. Channel gratings can also be manufactured from cast iron, ductile iron, and galvanised steel. If you’re installing a linear drainage channel at home, a plastic or aluminium grating is usually perfectly fine. Often your choice of material or colour will come down to aesthetic preference unless you need your channel to bear particularly heavy weight loads. You can read more about weight loads in the next section if you’re unsure. 

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Checking the weight load of your linear drainage channel

All channel drains come with an associated ‘weight load class’, which identifies the level of weight they can bear. They range from very low pedestrian-only weight levels for gardens up to 90-tonnes for runways, docks and heavy machinery. When choosing your linear channel drain, you will always find the weight load class written in the product description, so you will always know precisely what that particular drain is suitable for. 

Here’s a quick rundown of the basic weight load classes you might need to know about for installing a concrete or plastic channel drain at home:

Class A15: 1.5 tonnes

This is the most commonly-bought weight class of linear drainage channels, able to support up to a maximum of 1.5 tonnes in weight. They’re designed strictly for pedestrian-only traffic, ideal for installing in home gardens, paths and smaller patios.

Class B125: 12.5 tonnes

If you’re installing or upgrading a driveway, you’ll need to buy channel drains that carry the B125 weight load class. These are designed to support weights of up to 12.5 tonnes, making them suitable for domestic driveways, garage thresholds and larger patios that may need to support a higher level of footfall. 

Class C250: 25 tonnes

It is unlikely you will need channel drains carrying the C250 weight load class for a normal family household, but for slightly larger properties, this could be necessary. C250 linear drainage channels are designed to support loads of up to 25 tonnes and are typically used for small private car parks. 

Channel drains of D400, E600 and F900 weight load classes also exist, but these are designed for busy highways, industrial areas and airports, so you won’t need to buy anything this robust for your home landscaping projects!

Now you know everything there is to know about channel drains, we’ll move on to how to install them.

Tools needed for installation

How to install a plastic drainage channel at home

Whether you’re working on a brand new landscaping project from scratch or you’re simply trying to upgrade your groundwork to remove drainage issues, we’ll walk you through the basics of installing a linear drainage channel system at home. 

As the humble plastic drainage channel is the most popular type, we’ll use this as our example for the guide.

What you’ll need:

  • A draining shovel for digging your trench
  • Concrete or compact sand fill
  • Measuring tape
  • Saw or cutting tools for cutting drainage sections to a desired length
  • Mallet
  • Heavy-duty exterior masking tape (if using concrete)

Step 1: Prepare the area and plan the route 

First, you’ll need to decide where you want to lay your drainage, and where it will discharge its water. Most plastic channel drains discharge into the  main drainage area, such as your home’s drainpipe, via an endcap outlet. Still, some also discharge downwards into a sewer connection via a pre-cut pop-out outlet at the channel’s base. 

Your drainage channel should ideally start at the highest point on the ground, sloping downwards towards the discharge site. Spend some time planning the route and clearing the surrounding area to ensure the water will drain in the right direction. 

TIP: Make sure you’re not directing water to run into neighbouring properties, as this can cause damage and unwanted disputes. 

Step 2: Dig a trench to house the drainage channel

You will need to create a trench in the ground to house your linear drainage channel. You can use any shovel to do this, but a specially designed draining or trenching shovel will make short work of the task. Your trench should be wide enough and deep enough to house your plastic drainage channel, so the drainage channel grate sits 2 mm below the surrounding ground. 

You will also need to dig an extra 100 mm of depth to allow room for compacted sand or concrete as a base. And you’ll need to dig an extra 200 mm in width to allow 100 mm on either side of the channel for more sand or concrete backfill. 

Step 3: Pour sand or concrete base

Now you’ve got your neatly-dug trench, it’s time to add your base. If you’re installing a simple garden or patio drainage channel that will only bear pedestrian weight, it’s fine to use compacted sand. However, if you’re installing a driveway or threshold channel, it’s best to use concrete. Your layer of concrete or sand should be 100 mm thick.

Step 4: Insert your linear drainage channel

Now it’s time to lay the channel. Starting at your lowest point, begin lowering your sections of channel drainage into the trench, making sure all required end caps are already attached and your outlet is connected and sealed to the main drain pipe or sewer connection. 

You should start by installing your complete drainage sections first, then use your saw or cutting tools to cut any final sections to size at the end if you need to. 

Once your sections have been lowered into place, use your mallet to gently tap and press them into the concrete or sand base. You should do this with the drainage channel grate already attached, as this will help you make sure your drains are sitting at the right height (2 mm below the surrounding ground level) after pressing them into the trench.

Step 5. Backfill with more concrete or sand

Now you have your linear drainage channel sections laid in place, you should backfill the 1 mm gaps on  either side with more concrete or compacted sand. If using concrete, make sure you protect your channel grates with heavy-duty exterior masking tape before you start pouring to prevent any sticking and clogging. 

 Step 6. Leave for 72 hours

If you’re using concrete to backfill your channel drains, you’ll now need to leave them to cure completely undisturbed for at least 72 hours before exerting any pressure on them. 

That’s it! Now your property should be free from any unwanted water pooling or drainage issues. Please note, however, that the above steps are intended for use as a general guide only. You should always refer to the manufacturer’s instructions for the specific type of linear channel drainage you have chosen, as there may be more specific instructions and requirements to follow to make sure your warranties remain valid.

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