Garden Decking - How to Build a Decking Sub-Frame

Before laying decking boards, it is important to get the decking sub-frame exactly right to ensure that you will have a firm and easy-to-maintain deck.

Here are a few simple steps to take, in order to make sure that your garden decking is structurally sound and will last for years.

Things to Consider When Building a Sub-Frame

The Easy Deck Bearer (70 x 70 x 2400mm) insitu with decking boards, sat on gravel.


The first step is to create the frame upon which the decking boards will be laid.

The main decking joists of the frame need to run in the opposite direction to the way the deck boards are laid, approximately 40cm apart.

The level of the decking needs to be worked out prior to construction; it will need to be slightly sloped one way (a slope of about 1cm) for drainage purposes.

If you are building a frame on top of a patio, the timber frame should be around 5cm by 10cm.

Using Bricks

Decking can either be built straight onto a patio or placed on top of brick pillars in order to increase the height.

Bricks will need to be placed at frequent intervals of around 1.25 metres, along every second joist, so that the decking is not too springy once placed on top. 

A table and yellow flowerpot sat on top of the 3.6 x 3.6m Deck Kit with Railings - Square Spindles

Thinking Ahead

It is a good idea to put some weed control fabric in the decking base to stop unsightly weeds growing up between the deck boards.

For added effectiveness, we would recommend also laying pea-gravel on top of the weed control fabric.

The best way to hold all of the timber together is with galvanized screws, to minimise the level of upkeep required.

You will need to drill pilot holes for galvanized screws. However, if you use decking screws this will not be necessary.

Once the frame is completed it should be strengthened using cross members.

We hope this article has proved helpful to you. Here at Buy Fencing Direct, we specialise in decking boards and other decking products. Click here to browse our fantastic range of garden decking today.