Almost all cabro failure is caused by what is underneath it. Here is what a properly built compound needs.
The block is almost never the problem
When a compound sinks, rocks underfoot or grows puddles, clients usually assume they were sold poor blocks. Occasionally that is true. Far more often the blocks are fine and what was built underneath them was not.
Cabro is a flexible pavement. It distributes load through the interlock between blocks into a compacted sub-base, and that sub-base carries the weight. If it is thin, poorly compacted or laid on unsuitable ground, the surface will deform no matter how good the blocks are.
What a proper build-up involves
A paving job done properly involves work you will never see once it is finished:
- Excavation to formation level, deep enough for the full build-up rather than just the blocks.
- Removal of unsuitable material. Where there is black cotton soil, it has to come out. Paving over it guarantees movement.
- A compacted sub-base, laid in layers and compacted in layers, to a depth matched to the loading the surface will carry.
- Falls set out deliberately, so water runs somewhere you have chosen rather than pooling or running into a building.
- Edge restraint along every free edge. Without it the blocks migrate outward, the interlock loosens, and the pavement unravels from its edges.
- A laying course of sharp sand, screeded to a consistent depth.
- Jointing sand vibrated in, which is what actually creates the interlock. Skipping this leaves a surface that never locks up.
Choosing block thickness
Thickness should follow what will drive on the surface, and it is not a place to save money. Thinner blocks suit pedestrian areas, walkways and light-duty patios. A domestic driveway carrying cars needs more. A compound taking delivery lorries, school buses or heavy plant needs more again, on a correspondingly deeper sub-base.
This is why the specification for a school compound and a residential driveway are genuinely different jobs. A quotation that offers the same build-up for both has not been thought about.
What actually drives the cost
Beyond area and block thickness, the variables that move a paving price are: how much excavation and cart-away is needed, whether unsuitable ground has to be dug out and replaced, the sub-base depth the loading requires, how much drainage the site needs, the length of edging relative to area, and access for delivering material.
A quotation given per square metre with none of these established is a placeholder, not a price.
Drainage is part of the job, not an extra
Paving a compound removes ground that used to absorb rainfall. That water still arrives, and it now has to go somewhere. Where it goes should be a design decision — channels, gullies, a soak pit, or a connection where one genuinely exists — rather than whichever way the ground happens to slope.
Getting this wrong is how a new driveway ends up directing storm water into a house or onto a neighbour’s plot.