Knowing how to install cabro properly is the difference between a driveway that stays flat for decades and one that ruts after the first long rains. Most failures have nothing to do with the blocks. They come from levels, bases and edges done in a hurry. This guide walks through each stage the way a good crew builds it, with a “check before you pay” box at every step, so you can supervise a contractor or a fundi with confidence.
How to install cabro: the layers you are building
A cabro pavement is a stack of layers, each with a job:
- Ground (subgrade): the natural soil, trimmed and compacted.
- Base (subbase): a layer of well-compacted granular material, such as murram or crushed stone, that carries the load.
- Bedding layer: a thin, even layer of sand or quarry dust that the blocks sit in.
- Blocks: the cabro itself, laid in a pattern.
- Joints: filled with fine sand, which locks the blocks together.
- Edges: kerbs that stop the whole surface from spreading.
Preco lays its own cabro in exactly this way: on a compacted base over a sand bed, with an edge restraint such as a road kerb, and drainage channels where surface water needs carrying away.
Tools and materials you will need
- string lines, pegs, a spirit level or a dumpy level, and a measuring tape;
- shovels, a wheelbarrow and a rake;
- a plate compactor (a vibrating plate), not just a hand rammer;
- screeding rails and a straight edge for the sand bed;
- a block splitter or a cutting machine with a masonry disc;
- base material, bedding sand or quarry dust, and fine joint sand;
- kerbs, concrete for the kerb bed, and the cabro blocks.
Step 1: Set out the levels and the falls
Every good paving job starts with water. Decide where rain will run before anything is dug. The finished surface needs a deliberate fall, typically around 2%, towards a drainage channel, a lawn or an approved outfall, and always away from the house. Mark the finished levels on pegs and fix string lines to them.
Check before you pay: Ask the crew to show you which way water will run and where it will end up. If nobody can answer, stop.
Step 2: Excavate to the right depth
Excavation depth is the total of the block, the sand bed and the base, measured down from the finished level. For a typical home driveway on firm ground, that often means digging out roughly 250 to 300 mm. Remove topsoil, roots and soft pockets completely, because organic material rots and sinks.
Check before you pay: Measure the depth at several points against the string line. The bottom should follow the same fall as the finished surface.
Step 3: Compact the ground and build the base
Compact the exposed ground with the plate compactor. Then lay the base material in layers, typically no more than about 100 mm at a time, watering lightly and compacting each layer thoroughly before the next. On a home driveway the base is commonly around 150 to 200 mm after compaction. Heavier traffic or weak ground needs more, and that is a job for an engineer’s design. International guidance such as the Concrete Masonry & Hardscapes Association’s structural design note sizes the base from the expected traffic and the soil, not from the block.
The base is where cheap quotes save money and where pavements fail. In particular, black cotton soil needs special treatment. See our guide to cabro on black cotton soil.
Check before you pay: Walk on the compacted base. It should feel hard and firm, with no footprints and no spongy areas. It should also follow the fall.
Step 4: Set the kerbs before the blocks
Kerbs, or another firm edge restraint, go in before anyone lays the cabro, not after. Set them to a string line on a concrete bed, then haunch concrete behind them so that nothing can push them outwards. Let the concrete cure before any vehicle comes near.
Without a firm edge, blocks creep outwards under traffic, the joints open, and the whole surface loosens. Preco’s road kerbs are 915 mm long, so you need about 1.1 kerbs per metre of edge. Our article on kerb installation covers the details.
Check before you pay: Push hard on a kerb with your foot. It should not move at all.
Step 5: Spread and screed the sand bed
Spread bedding sand or quarry dust evenly over the compacted base. Then screed it flat with a straight edge running on rails, so that it ends up no more than about 25 mm thick once the compactor beds the blocks into it. The same CMHA guidance asks for a bed of consistent thickness, no more than 25 mm after compaction. Do not walk on screeded sand, and never use the bedding layer to fill dips in the base. Fix the base instead, because a thick patch of sand will settle unevenly.
Check before you pay: The bed should look smooth and uniform, with no footprints, ridges or puddles.
Step 6: Lay the cabro in the chosen pattern
Lay the blocks hand-tight onto the sand, starting from a straight edge or a kerb and working forwards on the blocks already laid, never on the sand. Keep the pattern square with string lines every few metres. Where vehicles drive, a herringbone pattern resists the push of braking and turning wheels best. Our guide to cabro designs explains the patterns.
Mix blocks from several pallets as you lay, so any slight colour variation spreads across the surface rather than showing as patches.
Check before you pay: Joints should be narrow and even, typically 2 to 5 mm, and the pattern lines straight.
Step 7: Cut and fit the edges
Fill the gaps at kerbs, drains and walls with blocks cut on a splitter or a saw. Avoid tiny slivers at the edges: a good layer adjusts the pattern so that edge pieces are at least about a third of a block. Small pieces break and work loose.
Check before you pay: Look along the edges. There should be no gaps filled with mortar or loose sand, and no thin slivers.
Step 8: Compact, fill the joints and compact again
Run the plate compactor over the laid blocks to bed them into the sand. Then brush dry, fine sand into the joints and compact again, repeating until the joints are full. Full joints are what lock the blocks together and stop water from washing the bedding out.
Check before you pay: Brush your hand across the surface. The joints should be full to the top, and no block should rock underfoot.
How long does cabro installation take?
Once you know how to install cabro, the timing makes sense. A typical 100 m² home driveway on firm ground usually takes a crew several working days. That covers setting out and excavation, the base, kerbs, then laying and compaction. Kerb concrete needs time to cure before vehicles use the driveway. Rain, difficult access and soft ground all add time. Your contractor should give you a written programme with these stages.
Common mistakes that shorten a driveway’s life
- digging too shallow, or leaving topsoil under the base;
- compacting the base in one thick layer instead of several thin ones;
- laying the blocks before the kerbs, or with no kerbs at all;
- correcting a bumpy base with extra sand;
- leaving joints half-empty;
- paving with no falls, so water sits on the surface or runs towards the house.
Each of these leads to the problems in our cabro maintenance guide: sinking, rocking blocks and weeds.
When to hire professionals
Learning how to install cabro on a garden path yourself is realistic. A driveway, a car park or an estate road is a different job, because it needs a plate compactor, accurate levels and experience with bases. Mistakes are also expensive to undo.
Preco’s own team lays the blocks we make, together with the kerbs and drainage, so you are not coordinating a supplier and a separate fundi. We price laying per square metre on top of the supply rate: KSh 300 per m² for Quad and Zigzag and KSh 350 per m² for the other designs. Base preparation depends on the ground, so we quote it for each site. Read more on our services page.
Book a site visit
Now that you know how to install cabro properly, let us quote yours. Send us the area in m², the site location, the design and thickness you prefer (or the traffic the surface will carry), whether you need kerbs and drainage, and what is on the ground now: an existing slab, murram or soil.
- Request a paving quote, or WhatsApp +254 718 429 063.
- See the cabro range and choose a thickness with our 60mm vs 80mm cabro guide.