Why is compaction the step that decides everything?
Compaction turns loose material into a load-bearing layer. If any layer under the paving still has air voids when the blocks go down, traffic and rain will finish the compaction for you, unevenly, and the surface will settle in patches. Good compaction is therefore not a finishing touch but the core of the structural work.
We compact the formation, then each lift of zahorra, then the blocks themselves once laid and jointed. Every stage uses a vibrating plate or roller suited to the area and the layer. Narrow strips beside walls and around manholes get extra attention, because a large machine cannot reach them and they are where settlement most often begins.
How is a sub-base compacted properly?
The short answer is in thin layers, at the right moisture, with enough passes. Spreading the full depth of aggregate and running a plate over the top only densifies the upper part; the bottom stays loose and moves later. Thin lifts are also easier to level accurately, so the final shape of the base follows the planned falls.
- Excavate to a firm formation and compact it before adding any material.
- Spread the first lift of zahorra evenly and to the planned falls.
- Dampen dry material so the fines bind; avoid saturating it.
- Compact with overlapping passes until the surface no longer moves underfoot.
- Repeat lift by lift until the design level is reached.
- Check levels against string lines or a laser before bedding.
On a hot, dry day aggregate can lose moisture quickly, so it is managed as the work progresses. After heavy rain, the formation may need time to drain before it can be worked. These are judgement calls made on site rather than fixed rules, and we would rather wait than compact material that is too wet.
What does compacting the finished paving achieve?
Once the blocks are laid and the joints filled with dry sand, the whole surface is vibrated. This beds every block into the grit, brings them to a common level and drives sand down into the joints so that the units lock together. A second sanding is usually needed because the joints take in more material than expected.
A rubber mat or protective sole on the plate prevents the faces of the blocks from being scuffed, which matters most with smooth or coloured finishes. Natural stone and some clay pavers need gentler treatment or different methods, which is one reason the material choice should be fixed before the work is planned.
What are falls and why does paving need them?
A fall is the gentle slope given to a surface so that rainwater runs off rather than standing on it. Block paving is not watertight: some water runs over the surface and some passes through the joints, so both the paving and the layers below need to be shaped to shed water in a controlled direction.
The fall always leads away from buildings and towards a point that can take the water: a channel drain, a gully, a soakaway area or a planted border. Water should never be directed towards a front door, a garage threshold or a neighbour's property. On a villa plot, where a driveway, a terrace and a pool surround may meet, the falls of each area must be designed together.
We do not quote specific gradients here because the right figure depends on the material, the size of the area, the surface texture and any architect's specification. What we do is mark the high and low points on site with you before the base is built, so the water route is agreed rather than discovered at the first storm.
Can block paving be laid on a slope?
Yes, block paving can be laid on sloping ground, and where a plot is on a hillside it is often a sensible choice because the textured surface and the joints give grip underfoot and under tyres. The steeper the slope, however, the more the design has to resist blocks creeping downhill and water running down the joints.
- Firm restraint at the bottom of the slope, usually a kerb in concrete, so the paving cannot slide.
- Intermediate restraints across long drives to break the run of paving.
- A pattern that resists movement, typically herringbone, rather than straight stretcher rows running downhill.
- Cross channels or gullies at intervals so water does not gather speed down the drive.
- A stiffer base, often soil-cement or concrete, where vehicles brake and turn on the gradient.
Very steep access ramps need a different discussion, including whether block paving is the right surface at all. Our sister site covers sloping driveways in depth, including garage ramps and access from the road. Steepness is not the only factor: the length of the ramp, how vehicles approach it and where its water ends up all count.
Where should the water go at the bottom?
Every fall needs a destination, and that destination must be able to cope. A channel drain across a garage entrance, a gully at the low corner of a patio or a gravel strip feeding a garden are all common solutions. Connecting to a public drain or altering the kerb on the street involves the town hall and is not something a paving contractor can authorise; requirements for any public-side work are set by each ayuntamiento and confirmed with it beforehand.
Where the volume of water is large, or the plot naturally sheds water onto the paved area from higher ground, a permeable surface can help. Our page on permeable paving and grass grids explains how water can be allowed through the surface rather than only across it.
If you already have standing water on existing paving, the cause may be a lost fall, a blocked outlet or a local dip from a weak base. Diagnosis and repair of that problem sits with our sister site for drainage and standing water.
How do pool surrounds change the rules?
Pool areas need falls that take splash water away from the pool edge and not back into the water or towards the house. Spain's Building Code, CTE DB SUA section SUA 6, asks for a pool surround of at least 1.20 m width, slip-resistance class 3 and construction that avoids puddling, within its scope of application. Whether a particular private villa falls inside that scope is something your architect or the town hall can confirm. In practice the pool surround is designed with the coping, the falls and the outlet in mind from the start. Terraces and pool areas are covered in depth by our sister site for pool surrounds.
How do we check compaction and falls on your job?
Before the blocks go down, we walk the prepared base with you or send you photos and a short video if you are abroad, showing string lines, high and low points and the outlet. After laying, a hose test on the finished surface confirms that water runs where it should. This simple check is worth more than any verbal assurance.
Compaction and drainage work are both part of a correctly built base, and are explained further in our guide to layers and base under block paving. For new paving or the replacement of an old surface, see our concrete block paving and paving replacement services. Send us a photo and the approximate m² – free, no-obligation quote.
Frequently asked questions
Can block paving be laid on a slope?
Yes. Sloping drives and paths are commonly block paved. The design needs strong restraint at the bottom, intermediate kerbs on long runs, a herringbone pattern, water outlets across the slope and often a stiffer base where vehicles brake or turn.
What gradient should my patio have?
There is no single figure that suits every patio. The fall depends on the paving material, its texture, the size of the area and any project specification. We agree high and low points on site before building the base so the water route is clear.
Why compact the sub-base in layers?
A compactor only densifies a limited depth. If the whole sub-base is placed at once, the lower part stays loose and settles later under traffic. Compacting in thin lifts gives a uniform, load-bearing layer from bottom to top.
Why do you vibrate the paving after laying?
Vibrating the finished surface beds the blocks into the grit, brings them to a common level and pushes sand down into the joints. That locks the blocks together so they share loads, which is what makes block paving strong.
Where should rainwater from my driveway go?
Away from the house and towards something that can take it: a channel drain, a gully, a soakaway or a planted strip. It should not be sent onto a neighbour's land or uncontrolled into the street. Public-side connections need town hall approval.
Does water pass through block paving?
Some does. Standard block paving sheds most water across the surface but a share passes through the joints, so the layers beneath also need falls and an escape route. Permeable systems are designed to let much more water through deliberately.
What makes paving creep down a slope?
Braking and turning vehicles, plus water running through the joints, push blocks downhill if nothing stops them. A concrete-bedded kerb at the bottom, intermediate restraints and an interlocking pattern such as herringbone resist that movement.
Is a pool surround subject to special rules?
Spain's Building Code, CTE DB SUA section SUA 6, requires a pool surround at least 1.20 m wide, slip-resistance class 3 and construction that avoids puddling, within its scope. Whether a private villa falls within that scope is a question for your architect or the town hall.
Can you show me the falls before the paving is laid?
Yes. We mark string lines, high and low points and the outlet on the prepared base and walk it with you, or send photos and a short video if you are away. A hose test after laying confirms the result.
What if my existing paving already holds water?
Standing water usually points to a lost fall, a blocked outlet or a local dip from a weak base. The fix depends on the cause, from clearing an outlet to lifting and relaying the area. Our sister site for sunken paving deals with that diagnosis.