To build a decking base on sloped uneven ground:
- Clear the area of all grass, weeds, and debris using a good quality spade
- Dig 1ft deep post holes
- Set the posts using post-mix so that the top is at or slightly above the desired height
- Fix joists to posts at the correct level using an electric screwdriver and 100mm wood screws. Cut off any excess post with a hand saw.
You are now ready to install the decking frame and decking boards on a level support structure
This method can also be used on generally lumpy and uneven ground to elevate the decking above the uneven surface. Of Course, you need to make sure that any edges are made safe using steps or barriers.
Method 2: Level supporting base
Best for Low-level decking
Downsides: Can require a lot of digging and shifting materials
- Type 1 MOT hardcore
- Old/cheap paving slabs
- Wood for frame and legs
If you want to lay decking at ground level or slightly above but have lumpy/uneven ground this is the best method we have found to do so.
The decking is going in front of the french doors on our example but the ground is uneven. The first thing to do is to work out what height you want the decking to be at. We will opt for the surface of the decking to be just below the lip of the doors.
- Mark out the area then excavate to 200mm below where you want the surface of the decking to be.
- Add and compact a 50 mm layer of type 1 MOT hardcore
- Build the decking frame
Pro tip: For quick, clean cuts use a chop saw.
- Lay out the paving slabs down the centre and along the edges of the area. These will act as solid supports to spread the weight of the decking.
- Set the decking on the slabs
Pro tip: There is a good chance that the slabs will not be even and that some parts of the decking will be too high or too low. Screw off-cuts in to add extra support and elevate the decking anywhere it is needed.