Ground Spike Installation

How to install ground spikes for your Hyperion® composite decking


The ground spike is a cost-effective and time-saving alternative to concrete foundations for small to medium sized structures such as decks, sheds or garden rooms.
Ground spikes create a surface onto which you can place pedestals as though it was a concrete base. While some ground spikes have joining components directly attached to the head, our MESA ground spikes feature a flat head for versatility. This flat-head approach means the type of pedestal you are using can be easily swapped out depending on the application.
Some examples of utilisation would include adjustable height pedestals for steps, or using slope correcting pedestals on sloping ground.
Ground spikes are used in soft-ground areas to provide a solid foundation on which to build a structure (such as deck foundations or shed foundations). They serve as an alternative to the traditional concrete base and the associated drawbacks which include long drying times, wasted aggregates and airborne dust.

How many ground spikes do you need?

The answer is.. it depends. The number of ground spikes will be subject to the kind of joists you are using and whether the project is residential or commercial - among other factors.
Building Regulations dictate that raised domestic decks, above 600mm from the ground, should be constructed to hold a distributed load of 3.0kN/sqm which is ~300kg per square metre.
Low level decks, under 600mm raised, can be constructed to 1.5kN/sqm (~150kg/sqm), and
Commercial decks should be constructed to 4kN/sqm (~400kg/sqm).
Therefore depending upon the type of ground you will probably require at least 2 spikes per square metre to support decking for a residential project. The limiting factor will normally be the spacing between the joists
Another consideration to the spacing is the size and strength of the joists that you are using. For Manticore joists please check the installation manual, if you're using timber then please comply with the
Timber Decking and Cladding Association guidelines

Ground Types

The figures below show the weight bearing capacity of each MESA ground spike. For each of the three ground conditions, the weights listed are estimates.

Poor Ground Conditions - 150kg

Loose Fine Sand; Alluvium; Soft-Firm Clays; Varied Clays; Fill

Medium Ground Conditions - 200kg

Loose to Medium Dense Fine to Coarse Sand; Firm to Stiff Clays & Silts

Good Ground Conditions - 300kg

Medium Dense Coarse Sand & Sandy Gravel; Stiff to Very Stiff Silts & Clays

Ground Spike Installation

Without the requirement for messy dirt removal and digging, the components of the system can be self-installed at an incredible speed with a trench rammer, or at very low cost with a sledge hammer - reducing labour times and the need for adequate site access associated with traditional concrete bases.
The first thing to do is always mark out the area that you are looking to install the decking over. The best way to do this is by positioning your pre-made substructure over the area where you will be installing your deck and then marking the ground spike positions.
Due to the size of the flat head of the ground spike you have some margin for error when originally being placed into the ground.
Remove the pre-made substructure and you are ready to install your ground spikes. From here there are two options for installing:

The sledgehammer method

You will need - a sledgehammer
  1. Wet the area where you are looking to hammer the spike into.
  2. Place a large block of wood (or Manticore plastic lumber) on top of the spike and hit repeatedly with a sledgehammer.
  3. The ground spike can be damaged if the head is struck by a sledgehammer - ensure the block of wood is large (and strong) enough.
  4. Every few strikes look to see whether the spike is still going straight into the ground and adjust.
Please note: If a rock is encountered under the spike it might need to be moved slightly.

The trench rammer method:

You will need - a trench rammer
Trench rammers can be hired out at a reasonable daily rate and provide a much faster mechanism for installation.
If you choose to go this route please follow all safety guidelines, use PPE and ensure you are installing the ground spikes as straight as possible.