Retaining Wall Blocks: Types, Prices and How They Work

Retaining wall blocks are heavy concrete units stacked dry, each course set back from the one below, to hold back a slope or bank. You see them on steep gardens, beside driveways and on terraced estates. Open plantable blocks are filled with soil and planted so the wall turns green; solid rock face blocks give a stone look. They need no mortar, but they do need a proper base, drainage and backfill. This page covers the types, design, building and prices. Send one free, no-obligation request and suppliers near you quote you directly.

Retaining wall blocks types

Plantable (open) blocks: hollow, wide units with a pocket for soil and plants, popular for garden banks and embankments.
Rock face or split face blocks: solid blocks with a stone-look face, often with a lip that sets each course back.
Interlocking segmental blocks: keyed or pinned together for a neater, steeper wall.
Large engineered systems: heavy units with soil reinforcement grids, for tall walls and roads.

For a free-standing boundary wall, use concrete blocks instead; retaining blocks are made to lean into soil.

Choosing blocks for your slope

Start with the height of soil to hold back and what sits above it. A low garden terrace under knee height is very different from a bank that holds up a driveway, a house or a road. Steeper set-backs and heavier blocks hold more; a gentle lean is more stable. Plantable blocks soften the look and let water through; rock face blocks look tidy beside modern houses. For anything tall, near a building or carrying traffic, have a structural engineer design the wall. A paving or landscaping team that has built retaining walls before is a good place to start.

Building a retaining wall that stays up

Most retaining walls that fail do so because of water and a poor base, not weak blocks. The basics:

dig out and compact a level, firm foundation, with the first course partly buried;
set each course back as the block design intends, never vertical;
put a drain pipe and free-draining stone behind the wall so water can escape;
backfill in layers and compact each one, not all at once;

Summer storms load a bank with water fast. Order sand and stone with the blocks.

Retaining wall blocks price and what to ask

There is no reliable published price list across the country. Small decorative rock face retaining blocks sell from about R60 a block at retail, and larger engineered systems are priced per project. The total depends on wall height and length, block type, digging, drainage, backfill and access for delivery. Ask the supplier or contractor:

how many blocks per m² of wall face, and the weight of each;
whether the price includes digging, drainage and backfill;
the tallest wall the block suits without an engineer's design;
how delivery and offloading work on a slope.

What to include in your request

Give the wall length and height
Say what sits above the bank
Choose plantable or rock face blocks
Say supply only or supplied and built
Mention truck access on the slope

Retaining Wall Blocks for different clients

Homeowners: terracing a sloping garden or holding back the bank beside a driveway
Builders and bricklaying contractors: retaining walls on sloping plots before the house platform is built
Housing developers and complexes: terraced retaining walls on hillside estates and along internal roads
Brickyards and block yards: block yards adding plantable and rock face retaining blocks to their range
New brick-making businesses: a small yard making plantable retaining blocks in steel moulds for landscapers
Farms and smallholdings: retaining walls for dam spillways, farm road cuttings and sloping yards
Municipalities, schools and public works: stormwater channel banks, road cuttings and school grounds on slopes
Landscapers and paving teams: planted retaining walls and terraces that turn a steep bank into beds

Frequently asked questions

What is the price of retaining wall blocks?

There is no reliable national price list. Small rock face retaining blocks sell from about R60 a block at retail, while plantable and engineered blocks are usually quoted per job. Digging, drainage stone, backfill and labour often cost more than the blocks, so ask for a price per m² of finished wall.

What types of retaining wall blocks are there?

The main types are open plantable blocks, solid rock face or split face blocks, interlocking segmental blocks that key together, and large engineered systems with soil reinforcement grids for tall walls. Plantable blocks suit garden banks, rock face blocks suit neat terraces, and engineered systems suit roads and big cuttings.

Can I build a retaining wall myself?

A low garden terrace of plantable or rock face blocks is a fair DIY job if you build a firm base, set each course back and put drainage behind it. Walls that are tall, hold up a driveway or a building, or sit on a boundary should be designed by an engineer and built by an experienced team.

Who will quote me for retaining wall blocks?

Send one request with the wall length and height, the block type and your address. We pass it to independent block yards, landscapers and paving contractors in your area, and they quote you directly. We do not make, sell or build anything ourselves, so you compare the offers and choose freely.

Stepped blocks that hold a bank of soil in place