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Main installing decking joists

How to Lay Decking on Uneven Ground

Timber decking is a lovely addition to any garden but there’s one big problem - it needs a fairly even base to work on. So does this mean if you have uneven ground that you can’t have decking?


No, it doesn’t, it just means you need to take a few extra steps to make sure your decking is as level as possible and solid. Let’s take a look at how to lay decking on uneven ground.


How to use a cemented support post system
This system is ideal to add decking to a sloping garden where the slope moves away from the house. It works for any type of decking including composite decking boards but it is a little trickier than some approaches because you need to create a decking base with cemented posts to support it.
To create the area on which to add the decking, you need to:


Step 1: clear all grass, weeds and other debris from the area to ensure it is smooth and level


Step 2: dig post holes that are 1 foot deep


Step 3: use post mix to set the posts so that the top of the post is at or slightly above the height you want to lay the decking on


Step 4: fix decking joists to the posts at the decking level with 100mm wood screws. Use a hand saw to remove any of the post that is over the top of this point


Once this is done, you can add the decking frame and begin to lay the boards of the decking on top of it. This means you have a level frame from the ground to the end of the decking where the posts and joists are found.


You can use this approach on lumpy or uneven ground if you want to. But there is another way to handle this type of problem.
How to use a level supporting base


The other approach is ideal for low-level decking on even ground that isn’t sloping. So overall, the garden is at one single level but there’s a lot of lumps and bumps in the ground that make laying the decking tricky.


There’s a lot of digging and manually shifting material with this method but it is the best way to handle uneven ground in an otherwise level garden.


You will need Type 1 MOT hardcore as well as some old or cheap paving slabs. You will also want some wood suitable to make legs and a frame, so treated to withstand being outdoors is advisable.


First, work out what height you want the decking to be at. So if this is leading out from patio doors, you will want the decking just below the door frame. Then you are ready to start work.


Step 1: mark out the area for the decking and excavate 200mm below the level you want the decking to be at when finished


Step 2: add and compact a layer of Type 1 MOT hardcore to around 50mm in depth


Step 3: build the decking frame so it looks like a ladder. You may want to make more than one section, depending on how big an area you are decking


Step 4: lay the paving slabs along the edges of the area and in a line down the centre. This creates a solid base for the decking frame to sit on


Step 5: add the decking frame to the slabs. If the decking is still not level, you can use cut-offs screwed in to add extra support and to get the frame to be as level as possible


You are now ready to lay the decking on top of the frame. You may also want to secure the frame into the paving slabs as well.


Building a solid decking
Having uneven or sloping ground doesn't mean you can’t have decking, you just need to take a few extra steps to prepare the ground for it. By using the right method of preparation, you can have a sturdy and level decking area in almost any garden.

Chosing the Decking

There is a massive choice of decking available nowdays. Timber Decking is generally the most price competitive, and this is available is multiple widths, thicknesses and lengths. Composite Decking Boards are increasingly popular as they come in a variety of on trend colours including silver grey and charcoal and they are extremely long lasting and very low maintenance. As you'd expect Armstrong Supplies only supply quality composite decking from leading brands such as Trex.

To help work our how much how much decking you'll need our Decking Calculator is very easy to use

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