Of course (as always, check with your local building authority). Some TuffBlock users will use TuffBlocks in combination with concrete-in-ground footings (e.g. in each corner) or use earth anchors to ‘tie-down’ their project.

TuffBlock uses a floating foundation system designed to let your structure move slightly with natural ground movement. This prevents the stress and cracking you often see in fixed, concrete-in-ground foundations.

The system was originally created for regions with extreme freeze–thaw cycles, where:The ground becomes too hard to dig, and Traditional fixed footings fail because they can’t flex with seasonal expansion and contraction.

By “floating” instead of being locked into the ground, TuffBlock keeps your deck or structure safer, more stable, and longer-lasting.

Short answer: No — TuffBlocks will not sink when installed correctly.

TuffBlocks spread weight like a concrete footing and won’t sink if placed on firm, compact soil. Just scrape away loose topsoil—no heavy compaction needed.

The system has been used for decades worldwide. All footings can move if soil is unstable, but TuffBlocks handle ground movement better and you can easily add more blocks for extra support if needed.

Yes. Simply level the ground under each TuffBlock and then level the structure above using extension posts supported in the pocket of the TuffBlock below (refer to the installation guide for more detail).

Alternatively, if the impenetrable surface is sloping at a severe angle it may be worth considering using an alternative support/footing/foundation.

Yes. Use them on concrete, soil, gravel and everything in between so long as it meets the “stable ground” criteria.

What is stable ground you might ask? Basically put them on any substrate which would be an acceptable base for concrete-in-ground footings, if the ground is not compact just clear away a few layers until you find compact earth.

UV stabilisers have been included in the manufacturing process which means TuffBlock is manufactured to the highest standard of any plastic product for use outdoors.

However, like any plastic product we recommend TuffBlock is not installed where it is exposed to direct sunlight as this will reduce its service life below 25 years.

This is exactly where the Floating Foundation System was developed for areas in the north (USA) where freeze and thaw ground movement is a major issue for traditional "dig a hole and pour concrete" structures. So TuffBlock is a perfect solution for their application.

You can find our Master FAQ here, with our full list of TuffBlock questions answered.