The thickness of a resin bound driveway surface is a technical specification that affects the durability and load-bearing performance of the installation. Understanding the recommended depth helps homeowners assess whether a contractor is proposing an adequate specification, and provides a basis for comparing quotes on a like-for-like basis.

The Resin Surface Layer

The resin bound surface itself, the decorative layer of aggregate mixed with UV-stable polyurethane resin, is typically applied at a depth of 15 to 18mm for driveways subject to vehicle traffic. Some contractors apply at 15mm as the minimum, while others specify 18mm as standard for residential driveways. The depth is measured from the finished surface to the substrate beneath. The aggregate size used in the mix affects the practical minimum depth; coarser aggregates require a slightly deeper application to ensure all particles are fully encapsulated in the resin.

Why Depth Matters

A surface that is too thin is more susceptible to cracking and delamination under vehicle loading, UV exposure, and freeze-thaw cycles. The resin layer must be deep enough to fully encapsulate the aggregate particles and provide adequate structural integrity. Contractors who apply resin at less than 15mm are applying below the recommended minimum for vehicle use, which compromises the longevity of the surface.

The Sub-Base Beneath

The resin surface sits on a prepared base, which may be an existing sound tarmac or concrete surface, or a purpose-built sub-base of compacted hardcore. For a new installation from scratch, the total construction build-up is typically 150 to 200mm from finished surface to formation, comprising approximately 100mm of compacted MOT Type 1 hardcore, 50mm of tarmac base course as a binding layer, and 15 to 18mm of resin bound paving on top. This three-layer system provides a stable, well-drained base that maximises the life of the resin surface above.

Application on Existing Surfaces

Where resin is being applied directly over an existing sound tarmac or concrete surface, only the resin layer itself is added. The combined depth of the new surface over the existing substrate is the 15 to 18mm of the resin layer. The existing surface must be structurally sound and free of significant cracks, as any movement or cracking in the sub-base will eventually reflect through the resin overlay.

Summary

The resin bound surface layer on a driveway is typically 15 to 18mm thick. Applied over an existing sound base, only this layer is added. For a new installation from scratch, the total construction depth is 150 to 200mm including sub-base, base course, and resin surface. Application below 15mm compromises durability. Always confirm the specified application depth when comparing contractor quotes.