Outdoor paving installation methods: traditional, gravel, sand, grass, pedestals and facade
How you lay an outdoor slab shapes the result more than the slab itself. It determines what the job costs, how many days it takes, whether it can be lifted tomorrow without breaking anything, and whether water drains away by itself or sits in puddles.
There are six systems. Each has its place, and choosing wrong is expensive: a terrace laid on sand with vehicle traffic ends up sunken, and a garden laid in mortar loses all the ground's permeability for no reason.
This guide covers all six, with their real advantages and —what almost nobody tells you— when not to use them.
1. Traditional installation (mortar or cement-based adhesive)
A bonded system using mortar or cement-based adhesives. It is the most suitable option for surfaces subject to heavy traffic.
Advantages
- High resistance to loads and stresses.
- Non-porous surface that prevents stains from being absorbed.
- Easy maintenance and cleaning, even with a pressure washer.
- Great long-term stability and durability.
When to choose it: vehicle access, commercial areas, ramps, steps, and any surface that will carry loads. Also when you want to be able to pressure-wash without shifting anything.
When not to: if you need access to buried services, if you want to keep the ground permeable, or if the paving is temporary. Lifting a traditional installation means breaking it.
You'll need mortar and cement-based adhesives suited to the format and the substrate.
2. Installation on gravel
A dry-laid system, directly on a compacted gravel base. Particularly suited to outdoor spaces such as gardens, terraces and perimeter areas.
Advantages
- No mortar or adhesive required.
- Allows excellent water drainage.
- Quick and simple to install.
- Makes it easy to replace individual slabs.
When to choose it: garden paths, house perimeters, pedestrian areas. It's the system with the best balance of cost, speed and drainage.
When not to: with vehicle traffic, or on steep slopes where gravel migrates.
The base is made with fine-graded, well-compacted gravel. If the ground is soft or sloping, it's worth using a flexible gravel stabiliser or, for heavier loads, a rigid geocell stabiliser: they stop the gravel shifting and the slabs working loose over time.
3. Installation on sand
A practical, economical solution for outdoor areas with moderate pedestrian traffic. The slabs rest on a levelled, compacted sand bed.
Advantages
- Flexible, removable system.
- Good drainage capacity.
- Adapts to uneven ground.
- Simple maintenance.
When to choose it: it's the cheapest and the one that best adapts to ground that isn't perfectly flat. Widely used around pools and for paths.
When not to: anywhere vehicles will pass, or in areas with heavy run-off —water washes the sand away and the slabs sink on one side—.
Decomposed granite (jabre or sauló) also works very well as a base: it compacts better than river sand and holds up longer.
4. Installation on grass
A dry-laid method that blends the paving into its natural setting, ideal for gardens and green areas. The slabs are laid directly on the grass or on a prepared base.
Advantages
- Excellent visual integration with natural spaces.
- No fixing materials needed.
- Can be taken up and repositioned.
- Keeps the ground permeable.
When to choose it: when you want a path that reads as part of the garden rather than as building work. It's the stepping-stone system: Japanese stepping stones.
When not to: if the slab is going to sit above the level of the grass, because you trip on it and the mower hits it. The slab has to sit flush or slightly below.
If what you want is for grass to grow through the paving and for a car to be able to drive over it, that's a different system: grass-concrete paving (grid pavers).
5. Installation on pedestals (raised flooring)
Pedestal installation is a dry-laid system widely used on terraces, roof terraces and technical areas. The slabs rest on supports, allowing perfectly level surfaces to be created.
Advantages
- Easy access to services hidden beneath the paving.
- Excellent drainage and ventilation.
- Clean, quick installation.
- Lets you compensate for unevenness in the substrate.
When to choose it: this is the star system for renovating terraces and roof terraces, for one specific reason: you don't touch the waterproofing. The paving simply rests on top with nothing drilled, and if one day a leak needs investigating, you lift four slabs and put them back.
It also solves the slope problem. A roof terrace has a fall to drain water away; with pedestals the fall stays down there doing its job, while the walking surface stays horizontal.
How many pedestals you need
Pedestals go at the corners of the slabs, and each one supports the four slabs that meet over it. The exact calculation is simple:
pedestals = (number of rows + 1) × (number of columns + 1)
A real example. A 3 × 3 m terrace (9 m²) with 60×60 slabs:
- 5 slabs per side → 25 slabs
- Pedestals: (5+1) × (5+1) = 36 pedestals
- Our pedestals come in packs of 4 → 9 packs
As a quick rule of thumb: in 60×60 format you need between 3 and 4 pedestals per m², and in 60×120 between 1.5 and 2.5. The smaller the terrace, the more the perimeter weighs and the higher the ratio.
Two things to know before buying
Slab thickness is not negotiable. Raised flooring is designed for 20 mm porcelain. An 8 or 10 mm tile supported only at its four corners will break under a person's weight. If your slab is thin, this system is not an option.
Our pedestals are fixed height, at 10 and 15 cm, and are levelled by stacking pieces to compensate for unevenness in the substrate. They are not the millimetre-adjustable screw type you see on large contracts. For a domestic terrace they work perfectly; for a technical roof terrace with complex falls, ask us first.
And a safety warning: on high, exposed roof terraces, loose paving on pedestals can lift in strong wind. In those cases ballasting or perimeter fixing needs to be assessed with the installer. It is not a minor detail.
6. Ventilated facade
Porcelain is an ideal facade material thanks to its low water absorption and high resistance to the weather. There are different fixing systems depending on the design and the technical requirements of the project: visible or concealed clips, and encapsulated or chemical anchors.
Advantages
- Improved acoustic, thermal and energy insulation.
- High weathertightness and protection for the building.
- Long service life with minimal maintenance.
When to choose it: energy retrofits of buildings. It's the air cavity between the wall and the cladding that does the thermal work.
When not to: this is not a DIY job. It's a system with a design, anchor calculations and a specialist installer.
Comparison table
| System | Traffic | Drainage | Removable? | Relative cost |
|---|---|---|---|---|
| Traditional | Heavy, including vehicles | None (surface only) | No | High |
| Gravel | Pedestrian | Very good | Yes | Low |
| Sand | Moderate pedestrian | Good | Yes | The lowest |
| Grass | Light pedestrian | Total | Yes | Low |
| Pedestals | Pedestrian | Excellent | Yes | Medium |
| Facade | — | — | Yes (technical) | High |
Trim pieces: where the paving meets something else
Outdoor paving hardly ever ends in a clean straight edge. There are steps, pool edges, drainage channels. Solving those junctions with pieces cut on site shows, and it shows badly.
The pieces that exist for this:
- Mitred step tread — for steps, with a mitred edge so the cut doesn't show.
- Mitred coping — edge trim for a pool or terrace.
- Internal corner and external corner — for corners, in sets of 2 pieces.
- Drainage channel and corner channel — waterjet cut, for pool perimeter drainage.
It's worth counting them when you place the order, not once the job has started: they are usually made to order and have a lead time.
Laying patterns
Before starting you need to decide the orientation and the layout. The most common patterns:
- Stack bond — joints aligned on both axes.
- Diagonal — turned 45°. Visually widens the space and disguises a room that isn't square.
- Third bond — each row offset by a third. This is the required pattern for long formats, see below.
- Random offset — joints staggered irregularly, natural look.
- Vertical — to stretch the space and gain visual height.
- Single and double herringbone — the wood-flooring classic, increasingly used in porcelain.
- Chequerboard — alternating two finishes or two colours.
About half bond: on long rectangular formats —60×120, 30×120— you should not offset by 50%. Large pieces have a minimal but real manufacturing warp, and offsetting by half a tile puts the centre of one against the end of its neighbour, creating a lip you can feel underfoot. That is why the correct offset is one third at most.
Levelling is not optional
This is worth reading twice, because it affects the warranty:
No claims for warp will be accepted on installed material if a levelling system has not been used.
It's the condition porcelain manufacturers set, and it is reasonable: large-format material has tolerances, and levelling clips are precisely what compensates for them. Laying a 60×120 by eye and claiming afterwards gets you nowhere.
The minimum tools for a traditional installation: a notched trowel suited to the format, levelling clips, a spirit level, a square, a rubber mallet, tile spacers, a cutter and a sponge.
Frequently asked questions
Can I lay a 20 mm slab straight onto soil?
On unprepared soil, no. You need a compacted base —gravel, sand or decomposed granite— that has been levelled. Without a base, the slab sinks unevenly in the first rainy season.
What joint should I leave between slabs when dry-laying?
Dry-laid on gravel or sand, the joint is open: you leave the gap and fill it with the same aggregate, or let the water through. On pedestals, the pedestal's own spacer tabs set the joint. A closed joint with grouting material belongs to traditional installation.
Can you drive a car over paving laid on gravel?
Not with loose-laid slabs. For vehicle traffic on a permeable base the system is different: geocells filled with gravel, which spread the load, or traditional installation on a concrete slab.
And after laying?
Post-installation cleaning, which is what decides how the paving looks for years afterwards. We explain it in detail in our cleaning and maintenance guide: which product for which type of dirt, and why hydrochloric acid destroys the grout.
In short
- Cars and loads → traditional.
- Garden and perimeters → gravel.
- Cheapest and uneven ground → sand.
- Blending into the green → grass, or grid pavers if a car goes over it.
- Terrace or roof terrace without touching the waterproofing → pedestals, with 20 mm slabs.
- Facade → ventilated system, with a proper design.
You can see all the options in garden paving and porcelain paving. Tell us the square metres, the use and what's underneath, and we'll tell you which system suits you and work out the materials —pedestals included—.
