A modular surface is only as good as the base it sits on. An uneven, poorly drained, or unstable base is the most common cause of court problems - from tile warping to player injuries. Before you start planning a backyard or multi-sport court, it is worth knowing what base is required and where to begin.

What you can lay a modular court on

Modular surfacing requires a hard, level, and stable base. We do not lay it directly on soil or gravel - gravel is part of the sub-base under the hard surface, not the base for the modules.

Acceptable bases include:

• Existing hard surface - paving blocks, asphalt, an old acrylic court, or a concrete slab. If you have something like this in good technical condition, you can lay modular tiles directly on it. That saves significant time and cost.
• Paving blocks - a good base for a modular court, provided they are stable, do not sink, and are sufficiently level. There is no point laying new blocks solely to cover them with modules - if you are starting from scratch, it is more cost-effective to build a gravel sub-base under concrete or asphalt.
• Asphalt - mainly used on school courts and where use intensity is higher. Very level and durable surface, more expensive than concrete to install but proven outdoors.
• Concrete slab - the most stable and durable base. Standard for backyard courts and professional sport facilities. Most expensive to build, but gives the best foundation for years.

What about soil? Direct installation of modules on the ground is only possible temporarily - for a few days during an outdoor event. It is not suitable for permanent use: soil settles, ruts and water pools form after rain, the surface loses levelness, and court life shortens dramatically.

Step 1 - layout and excavation

Start with precise layout of the backyard court area including run-off zones - minimum 1-1.5 m beyond each line. Then excavate to a depth matching the planned layers, typically 30-40 cm from the finished surface level.

At this stage, check underground utilities - power cables, water pipes, and sewer lines must be mapped before any digging. If you plan court lighting, lay cables now - before the pour. Doing it afterward means chiseling.

Step 2 - gravel sub-base

Gravel is the foundation of the whole structure - not the base for modules, but the base under the hard surface. A proper sub-base consists of:

• Geotextile fabric - laid at the bottom of the excavation. Separates native soil from gravel and prevents root growth.
• Coarse gravel (crushed stone or gravel) - 15-20 cm layer, mechanically compacted. Provides drainage and stability.
• Fine gravel (aggregate or sand) - 5-10 cm leveling layer, compacted.

On this prepared sub-base, concrete is poured or asphalt is laid - only then do modular tiles go on top.

Step 3 - concrete slab

For backyard courts, a concrete slab is most commonly used. Standard parameters:

• concrete class minimum C16/20, reinforced with mesh or distributed reinforcement,
• slab thickness 10-15 cm,
• expansion joints every 3-4 m - concrete moves with temperature changes,
• curing time before laying surfacing: minimum 28 days.

If you plan a fixed hoop, the post foundation (typically 60 × 60 × 100 cm) is built together with the slab pour - not after it has hardened. That is one of the most common mistakes when building backyard courts.

Step 4 - drainage slope

The concrete slab must have a slope of 0.5-0.6% in one direction. On a 10 m court that is a 5-6 cm level difference between the high and low end - players do not feel it, but water drains efficiently after every rain. Without slope, even the best modular surface will not protect the court from puddles.

Slope direction: toward lawn, rainwater tank, or drain manhole - never toward the house or garage foundation.

Step 5 - level check before installation

Before laying tiles, check base levelness with a 2-metre straightedge. Allowable deviation is 2 mm over 2 m. Modular surfacing transfers base unevenness 1:1 - it does not level it, it mirrors it. Larger deviations must be corrected before installation.

Summary - what to choose

For a backyard court, the best compromise between cost, durability, and ease of construction is a well-compacted gravel sub-base under a concrete slab. If you already have level, stable paving blocks, asphalt, or concrete - you can lay modules directly on them. Direct installation on soil or gravel is not an option for permanent use.

Questions about the base for your court? Hoop And Court advises at every stage of the project - contact us before work begins.