On this page you find a list of Technical Queries.
If you cannot find the answer to your query, then please use the contact page to email Terraforce directly.

On this page you find a list of Technical Queries.
If you cannot find the answer to your query, then please use the contact page to email Terraforce directly.

When can I use TERRAFORCE blocks?

TERRAFORCE retaining walls are suitable for a range of projects from the home garden to major civil construction projects. If you have any queries about the suitability of TERRAFORCE for your project, or require a construction drawing, please contact us.

What type of foundation do I need?

For low walls a well compacted sand and gravel foundation is usually adequate. Higher walls will likely require a concrete foundation. Whatever the height of your wall we can provide you with a construction sketch, free of charge, indicating the type of foundation you require.

What backfill is required for wall strength?

Blocks should be filled with material as specified by an engineer, such as garden soil, clean sand, gravel or concrete (reinforced if needed). However, low garden walls that are meant to be plant supportive need only be filled with the best garden soil available.
On the horizontal plane, the blocks interlock via the convex and concave shape of the blocks that interact with one another. On the vertical plane, interlocking strength is gained by the block infill which functions like a interlocking core. Infill materials such as coarse gravel or concrete obviously have a higher core strength than sand or garden soil. No pins or interlocking lips are involved consequently there is no interference with versatility in alignment and inclination.(near vertical to 55 deg.)

Must I stack blocks like brickwork?

It’s advisable to build the TERRAFORCE wall by staggering the blocks. It will also enhance the look of your wall.

What are the curve restrictions?

Although very tight curves can be packed, it is recommended that curves smaller than 500mm (18") should be avoided. Right angle corners can be created by cutting interacting blocks with an angle grinder to suit.

Round Face or Straight face?

It doesn’t matter, stability is not affected. The TERRAFORCE block is double faced with one face rounded and the opposite side having the “rock face” finish. This reduces the cost of having to purchase individual round or rock face blocks.

How do I install a Wall?

On our website and in our brochures you can find illustrated installation details. Click here for a step by step illustration of a TERRAFORCE installation.

What about drainage and backfill?

The wall itself and the foundation are important but the drainage layer is just as important. A layer of coarse, well draining material of not less 300mm (1ft) behind the blocks which is well compacted is suggested. Click here to see a typical cross section. The engineer may also specify a permeable drainage pipe above foundation level. Surface water should at the top of the wall should be sloped away to appropriate drainage.
Inadequate compaction of the backfill and of the drainage layer are the cause of some spectacular failures that have been seen in segmental block walls. Backfill for relatively high walls must be approved by the engineer and compacted to his specification, and care must be taken to prevent surface water ingress from above the wall. Closed face Terraforce blocks will ensure the long term integrity of the compacted backfill.

Can the wall be terraced?

TERRAFORCE blocks are ideally suited to creating terraces. There are many examples of terraced gardens in our gallery section. TERRAFORCE walls can be merged seamlessly from near vertical to a low 55 degree inclination by simply offsetting each row of blocks.

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