Permeability matters for several practical reasons: planning regulations require front driveways to drain properly, sustainable drainage reduces the strain on local drainage systems and helps prevent flooding, and a permeable surface manages surface water better on sloped or waterlogged ground. Resin bound driveways are widely marketed as permeable, but the full picture is slightly more nuanced than it initially appears.

This guide explains what permeability means in the context of driveways, whether and when resin driveways are genuinely permeable, and what the planning implications are.

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The Planning Permission Background

In England, permitted development rights were changed in 2008 to address the growing problem of front gardens being paved over with impermeable surfaces. Surface water that previously soaked into gardens was instead running off into roads and drains, increasing the risk of localised flooding.

Under the current rules, you can pave over a front garden without planning permission only if the surface is permeable, or if water from it is directed to a permeable area such as a lawn. If you want to install an impermeable surface on a front garden of more than five square metres, you need planning permission. The rules apply to the front of the property; rear and side driveways are generally not affected by these specific drainage requirements.

This is one of the main reasons resin bound driveways have grown in popularity. Provided they are installed correctly, they count as permeable surfaces and avoid the need for a planning application.

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Is Resin Bound Actually Permeable?

Resin bound surfacing, in which aggregate is fully encapsulated in resin and laid as a smooth surface, is inherently porous. The gaps between the aggregate particles, which are not filled by the resin, allow water to pass through the surface layer and into the layers below. This is the fundamental characteristic that makes resin bound a permeable surface material.

However, the permeability of the finished driveway depends on more than just the top surface. For water to drain away effectively, the entire construction, including the base layers beneath the resin surface, must support drainage.

The sub-base matters

Resin bound is typically installed over one of two types of sub-base: a solid, impermeable base such as existing tarmac or concrete, or a permeable open-textured base such as Type 3 crushed stone or SuDS-compliant aggregate. When laid over an impermeable base, water passes through the resin surface but then cannot go further down. It instead spreads within the base layer and must drain off to the sides. This may still provide adequate drainage in practice, but it does not constitute a fully permeable system from surface to ground.

A fully permeable installation uses a permeable sub-base, typically at least 150 millimetres of open-graded aggregate, so that water can pass from the surface through the base and into the subsoil. This is the construction method required for the driveway to comply with Sustainable Drainage System requirements and to satisfy the planning permission rules definitively.

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Resin Bonded: Not Permeable

Resin bonded surfacing, the lower-cost alternative in which aggregate is scattered over a resin-coated base, is not permeable. The resin coating seals the base surface, and the aggregate sits on top rather than being embedded in a way that allows water through. Resin bonded driveways require planning permission if they cover more than five square metres at the front of a property, just as any other impermeable surface would.

It is important to be clear about which type of resin product is being quoted and installed. The price and visual similarity between resin bound and resin bonded mean that misunderstandings occur. A resin bonded surface will be cheaper initially but requires planning permission and sheds stones over time.

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How Long Does Permeability Last?

One concern with permeable surfaces is that they may become clogged with fine particles over time, reducing their drainage capacity. Resin bound surfaces can gradually accumulate fine silt, leaf debris, and other material in the voids between aggregate particles. In practice, the drainage capacity of a well-installed resin bound driveway takes many years to reduce significantly, and regular cleaning with a pressure washer or leaf blower helps maintain the voids.

If permeability is lost over time, the surface still functions as a driveway but no longer meets the planning requirement for a permeable surface. In practice this is rarely a significant issue within the normal lifespan of a resin driveway, but it is worth being aware of as a long-term consideration.

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Permeability in Practice: Water Management

Beyond the planning question, permeability has practical advantages for water management on a residential driveway. A permeable surface avoids puddles forming after rain, reduces the amount of water running across the driveway and onto the road or into the garden, and helps manage surface water on sloped or imperfectly drained ground.

In areas prone to localised surface water flooding, a permeable front driveway can make a small but meaningful contribution to managing rainfall where it falls rather than allowing it to add to the peak flow in street drains.

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Summary

Resin bound driveways are permeable by nature of their construction, but the full drainage performance of the system depends on the sub-base as well as the surface layer. For planning purposes and for genuine sustainable drainage, the sub-base should be an open-graded permeable material rather than solid tarmac or concrete. Resin bonded driveways are not permeable and require planning permission for front driveway installations above five square metres.

When specifying a resin bound driveway installation where permeability is important, confirm with the contractor that the full construction, from surface to sub-base, meets permeable drainage requirements.