If you’re planning on installing a decking in your garden, it’s absolutely imperative that you prepare the ground carefully and considerately.
Otherwise, you run the risk of your investment not reaching its full predicted lifespan.
But, with a well-prepared base, you can minimise the likelihood of many of the most common issues to affect decking, including weeds, drainage complications and instability.
So, to ensure you’re ticking all the boxes for decking preparation, keep reading.
Below, Barnard Fencing’s expert team have shared their guidance for understanding when a membrane is needed, the benefits it offers, and other top tips for preparing the base for your decking.
How to prepare the ground before installing decking
Before you start to install your decking boards or joists, you’ll need to carefully prepare the ground that will sit underneath the structure.
These preparation methods are all designed to give the decking a stable base for the long-term, while also preventing excessive moisture build-up, or weeds growing under and through the structure.
Generally speaking, the recommended steps for ground preparation are as follows:
- Clean up the area – Once you’ve marked out the area where your decking will sit, clear the area of debris, grass, weeds and other plants. Not only do you want to make sure any debris is removed, but that all organic matter is removed, too.
- Remove the soil’s top layer – Then, remove the top layer from the soil (usually, we recommend removing around 5-15 cm from this top layer). This will ensure the surface is level, and that there’s enough room to layer the decking’s base.
- Compact the soil – Once level, compact the soil with a tamp.
- Lay the drainage materials – We would recommend adding a drainage layer (e.g. gravel or crushed stone) to improve drainage in the area underneath the decking. You may also want to add a slight gradient to the ground under the decking, but this is optional.
- Install your membrane under the decking’s subframe – More details on this step below.
Do you need a membrane under your decking?
Adding a weed membrane isn’t a mandatory part of installing a decking. But, it is highly recommended.
It’s especially key if your decking is going to be installed on top of soil or grass.
This is because a weed membrane is, by far, the most effective way to inhibit weed growth.
A weed membrane is a thin fabric that is positioned inbetween the soil and the decking. The membrane blocks sunlight from reaching the soil, thereby preventing almost all weeds from being able to grow in this area. At the same time, the fabric is designed so that it still allows air and water to pass through it, meaning the membrane doesn’t compromise the health of the soil underneath.
Weed membranes are specifically engineered to prevent the growth of weeds and plants (which would otherwise grow up and through the gaps inbetween your decking boards). As a result, they significantly reduce the maintenance requirements of your decking (as you don’t need to spend time regularly tackling these pesky weeds).
Beyond being aesthetically unappealing, weeds can cause real problems for decking.
This is because, if the weeds are allowed to grow, they can block your decking’s drainage channels. This can quickly lead to moisture building up. If unaddressed, high moisture levels can result in staining, pooling water and damage to the boards.
When is a weed membrane most important?
While weed membranes are recommended for msot decking installations, they are particularly important if your decking is being installed on top of soil, grass, or garden beds.
But, even if your decking is being installed over concrete or paving slabs (for example), you will still need to assess the area.
For example, if your decking is being installed in an area that is surrounded by flower beds or vegetation, then the membrane may still be a valuable addition.
If you’re not sure whether a membrane would be necessary for your decking, speak to your decking supplier. They’ll be able to advise you of the best practice approach.
How to install a weed membrane
Installing a weed membrane is a fast and straightforward process.
The typical steps recommended for installation are:
- Prepare the ground (following the steps outlined above)
- If there were existing weeds in the area (before clearing), spray the area with weed killer
- Lay the membrane across the entire area where the decking will be installed
- Ensure the membrane sheets overlap each other by around 150mm (this will prevent any gaps, which would compromise the membrane’s performance)
- Secure the membrane in place (using ground pins or staples)
At Barnard Fencing, we are a professional decking supply and installation specialist, trusted by homeowners across the UK.
So, to find out more about best practice decking installation, or to explore our product range, don’t hesitate to get in touch.
