Why do I need to use Weed Mat?

Cladco Heavy Duty Weed Mat should be an essential addition to any Cladco Decking substructure that’s installed outside over grass, flower beds, or on loose soil. The Heavy Duty Weed Mat material should be installed before laying any Cladco Decking Boards and also before any supporting Joists or Posts.

Weed Mat is designed to block any natural light reaching the soil, which in turn will slow down and eventually stop unwanted plants or weeds from growing underneath your Decking.

Without Weed Mat, you’ll likely be pulling up weeds or other plants through the gaps in your Decking Boards without removing the roots, which will not prevent them from continual growth throughout the year.

Weed Mat will help prevent this from happening and keep your Decking area looking great for many years down the line.

Garden with shed and flowers

How do I prevent weeds growing under my Decking?

After spending time and money on your brand-new Cladco Decking, the last thing you want to see is a tall, unsightly weed growing up through the gaps in your Decking Boards.

Some weeds can grow back if a small part of their roots still remains in the ground, so making the right preparations is vital.

Before installing Cladco Weed Mat, we recommended spraying the weeds with weed killer a couple of hours before removing them entirely. Using weed killer will make sure the plants absorb the weed killer solution and goes into the roots (always refer to manufacturer’s instructions first).

Start by removing existing weeds and clear away any obstructions and turf to create a level ground. Once the Weed Mat has been installed, laying gravel or chippings down over the Weed Mat is also recommended to help block out light and increase the temperature underneath the Weed Mat.

Weed Mat installation with chippings

How does Weed Mat work?

Heavy Duty Weed Mat works by the blocking out an essential component of plant growth – sunlight. By removing sunlight completely, weeds are unable to grow and spread. So long as the Weed Mat isn’t split or torn in any places, plants are effectively blocked from growing through your Decking Boards.

Weed Mat is made up of a heavy duty, woven material with a cross fibre polypropylene pattern. The solid material is tough yet porous, allowing water to drain through to prevent water pooling.

What’s more, correctly installed Weed Mat will generate enough heat that will help to kill off weeds and any seeds in the soil. This can be helped by placing mulch or other gravel on top of the Weed Mat.

The best way to prevent weeds from growing up from underneath your Decking is to lay down Weed Mat and secure using Ground Pins. Overlapping Heavy Duty Weed Mat as you go will help to prevent any weeds from growing up through the joins in the Mat.

Finished garden area covered with gravel

Will Heavy Duty Weed Mat kill grass?

Weed Mat is a semi-permeable fabric that blocks out light but allows for water and nutrients to soak through into the soil underneath. This keeps the soil fed but any plant growth is hindered by the heat and lack of light.

We recommend removing any large weeds before laying down the weed mat to start with a level ground. A lot of people will remove the grass completely before laying Weed Mat, however this will increase labour and time.

Where does Weed Mat go?

Installing Weed Mat will need to be the first thing to lay down when starting your Decking project in your garden. Cut the Weed Mat to fit around any obstacles or trees, and fold the Weed Mat where required around the edges to create an extra thick edging.

Weed Mat goes under the Decking Boards and underneath the decking frame, Joists or Posts that you are planning to install.

Weed Mat installation around tree
FInished deck with Weed Mat installed underneath

Weed Mat vs black plastic

Black plastic is commonly used to kill weeds as a replacement to using Heavy Duty Weed Mat. This is effective up to a point, because black plastic will cut out natural daylight that helps reduce plant growth.

A major problem with black plastic is that it is not porous and so will not allow water to pass through its surface and into the soil beneath.

This can cause water pooling on top of the plastic surface in heavy rainfall. Puncturing holes into the plastic surface is a workaround to this, however this could encourage plant growth through the holes over time so it’s not recommended.

What can also happen is water condensation can form on the underside of the plastic surface when it gets hot and will soak the ground underneath.

For more information on how to install Cladco Heavy Duty Weed Mat, follow our Installation Guide online.