Resin Bonded vs Resin Bound: Key Differences, SUDS Compliance, Appearance and Longevity

Quick Answer: Resin bound is permeable (water drains through), 15–18mm thick, mixed wet, trowelled, SuDS-compliant for front drives over 5m², lasts 15–20 years. Resin bonded is impermeable (water runs off), 3–6mm thick, scattered onto fresh resin, fails the SuDS test, lasts 8–12 years and looks similar at a glance but performs very differently.

Summary

The two products live in adjacent shelves of the same builders' merchant and are routinely mixed up by homeowners — and not infrequently by contractors who should know better. The mistake is expensive: a homeowner who specifies "resin" expecting bound and gets bonded ends up with a non-SuDS-compliant front drive, and either a planning enforcement letter or a hard conversation about who pays to lift it.

Resin bound and resin bonded use the same family of polyurethane resins and the same range of decorative aggregates, but the construction is fundamentally different. Bound is a homogeneous matrix of resin-coated aggregate, trowelled at significant depth, that allows water through the spaces between coated particles. Bonded is a thin layer of dry aggregate scattered onto wet resin, where the gaps are filled by the resin film itself.

This article puts both products on the same page and walks through the regulatory, technical, aesthetic, and lifecycle differences. Most domestic projects today should specify bound — bonded has narrow legitimate use cases (path overlays, anti-slip pedestrian areas, ramps with high grip needs) where its impermeability isn't a problem.

Key Facts

• Bound is permeable — water drains through the matrix into a porous base
• Bonded is impermeable — surface tension carries water off to drainage
• SuDS compliance — bound passes GPDO Class F; bonded fails unless drained to soakaway in curtilage
• Bound depth — 15–18mm domestic, 22mm+ heavier use
• Bonded depth — 3–6mm typically, can be as thin as 2mm
• Bound mix — 80kg aggregate to 6.5–7.5kg two-pack polyurethane resin, mixed before application
• Bonded application — primer + resin + aggregate scatter (broadcast) within minutes
• Bound base — porous asphalt or open-graded concrete
• Bonded base — any sound base; standard tarmac, concrete, or paving
• Bound longevity — 15–20 years quality system
• Bonded longevity — 8–12 years before re-coat needed
• Bound appearance — open matrix texture, can look slightly granular
• Bonded appearance — closer to a smooth coloured concrete topping, more uniform colour
• Bound cost (2026) — £85–£120/m²
• Bonded cost (2026) — £50–£75/m²
• Bound repair — patching possible; visible patch
• Bonded repair — re-broadcast aggregate over fresh resin
• Bound slip resistance — naturally textured, R11–R12
• Bonded slip resistance — depends on aggregate scatter density; can be low if surface fills with resin

Quick Reference Table

Detailed Guidance

How resin bound is constructed

The aggregate is dried (kiln-dried, moisture <0.2%) and mixed in a forced-action paddle mixer with a two-pack polyurethane resin (Part A polyol + Part B isocyanate). The resin coats every particle of aggregate, leaving the inter-particle voids open. The mixed material is poured onto a primed permeable base (porous asphalt or open-graded concrete) and trowelled to depth.

Because the aggregate is fully coated and the matrix has continuous void space, water passes through the surface into the base layer below — the surface is genuinely permeable, with infiltration rates typically 200–500 mm/hour, well above any UK design storm.

The construction is slow because of the wet-mix step. A two-person team typically lays 50–80m² per day depending on access and conditions.

How resin bonded is constructed

The base is primed (often with a tack coat of the same resin, thinned), then a film of two-pack polyurethane resin is brush- or roller-applied at 0.7–1.5 kg/m². Before the resin sets (typically within 5–15 minutes depending on temperature), dry aggregate is broadcast (scattered) by hand or via a hopper across the wet film. The aggregate sticks where it lands; excess is swept off and recovered after the resin sets.

The result is a mosaic of single-stone-deep aggregate held by a continuous resin film. The resin layer is typically 1–3mm thick and the aggregate sits proud. Water cannot pass through the resin film — the surface is impermeable.

Bonded works on any sound base because it doesn't rely on the base for drainage. Tarmac, concrete, even existing paving slab can be coated.

Why the SuDS difference matters

The 2008 GPDO amendment that introduced the 5m² rule on front drives explicitly defines compliant surfaces as those that allow water to "drain freely". Bound qualifies because runoff infiltrates the surface and reaches the porous base. Bonded does not qualify because it rejects all runoff to the surface.

Bonded can be made compliant by directing surface runoff to a permeable area within the property (lawn, gravel border) or to a soakaway inside the curtilage — same options as standard tarmac or concrete. But the surface itself is not permeable.

For the homeowner this matters because bonded specified for a front drive over 5m² without a runoff route means planning permission is required. Many homeowners discover this only after the drive is installed and a planning enforcement officer or a worried neighbour raises it.

Aesthetic differences

Both products use the same aggregates so colour palette is similar, but the look in service is different:

• Bound — matt, slightly textured, the aggregate visibly sits in a matrix; the surface darkens noticeably when wet (typical of porous surfaces). Some people describe it as looking "like wet sand" when fresh.
• Bonded — closer to a coloured concrete or stipple-finish topcoat. The aggregate sits more uniformly and the resin between particles gives a slight gloss. Wet-look effect is less pronounced because there's no matrix to darken.

For a contemporary smooth aesthetic, bonded can look more refined. For a natural gravel look, bound looks more authentic.

Longevity and failure modes

Bound systems typically last 15–20 years before the surface starts to lose stones at edges or near gates where wear is concentrated. Failure modes:

• Edge unravelling — most common, where stones detach from the matrix at points of high wear
• Yellowing — only if cheap aromatic resin was used
• De-bonding from base — usually a base failure (porous asphalt cracking)

Bonded systems typically last 8–12 years. Failure modes:

• Aggregate loss — the single-stone layer wears off, exposing bare resin film
• Resin embrittlement — UV degradation makes the resin film stiff and crack-prone
• Edge failure — bonded edges chip more easily than bound

Bonded "renewal" is often a re-broadcast — clean the existing surface, apply a new resin film, scatter fresh aggregate. This is straightforward and at 6–8 years is a sensible refresh.

When to specify which

Choose resin bound when:

• Front driveway over 5m² (SuDS compliance)
• Path or patio where you want a permeable surface
• Replacing an existing failed permeable system
• Anywhere drainage to a soakaway is constrained
• Premium aesthetic budget

Choose resin bonded when:

• Overlaying an existing sound impermeable surface (tarmac, concrete)
• Anti-slip ramp or gradient where high grip is the priority
• Pedestrian path where SuDS rule doesn't apply
• Budget-constrained where bonded saves £30+/m²
• Repair/refresh of an old bonded surface

Hybrid approaches

Some installers offer a hybrid: bonded surface course on a permeable base with breaks (drainage gaps) at intervals. This isn't recognised SuDS-compliant — the surface itself is impermeable, regardless of what's underneath. Marketing claims of "permeable bonded" are usually inaccurate; ask to see the manufacturer's data sheet and confirm hydraulic conductivity figures.

Frequently Asked Questions

Can I tell the difference by looking?

Sometimes. Bound has a matrix you can see — gaps between coated stones. Bonded has stones sat in a smooth resin background. Run a wet finger across the surface: bound will absorb the water; bonded will let it bead. A clear-cut test: pour a small jug of water on the surface and time the disappearance — bound drains in seconds; bonded just spreads.

Can I convert bonded to bound?

Not directly. The base layer is wrong (impermeable for bonded, permeable for bound). Conversion means stripping back to base, replacing the base with porous asphalt, then applying bound. In practice it's a full re-do, not a conversion.

Why is bound so much more expensive?

Three reasons: (1) the wet-mix process is slower and labour-intensive; (2) more resin is used per m² (6kg/m² vs 1kg/m²); (3) the base requires porous asphalt rather than standard tarmac. Material cost and labour drive the £30–£40/m² difference.

Is bonded suitable for vehicular use?

Yes for occasional vehicle use, but the edges fail first under tyre scrubbing and stones loosen at the wheel-overrun zone. For a vehicular drive, bound is more durable. For a pedestrian path with occasional service vehicle access, bonded is fine.

Can I install either in winter?

Both need temperatures above 5°C and rising for the resin to cure. The realistic UK installation window is April–October. Some "winter formula" resins cure to 0°C but they're more expensive and the standard advice is to wait for spring.

Regulations & Standards

• GPDO Schedule 2 Part 1 Class F — front-driveway SuDS rule (5m² impermeable threshold)

• BS 7533-13:2009 — Code of practice for the design of permeable concrete block pavements (relevant for bound base layers)

• BS EN 13242 — aggregates for civil engineering and road construction

• EN 13501-1 — fire classification (resin systems typically Cfl-s1)

• Approved Document H Section 3 — surface water drainage

• British Association of Landscape Industries (BALI) — installer accreditation

• SureSet technical comparison — manufacturer side-by-side guidance

• Addagrip product selector — second major UK system supplier

• BALI design guides — installer best practice

• Defra permeable surfacing guidance — official SuDS compliance reference

• resin bound paving guide — full installation method for bound

• SuDS regulations for driveways — front-drive 5m² rule

• resin bound gravel surfacing — overview of the surface family

• tarmac driveway installation — alternative impermeable surface

• driveway drainage channels — managing runoff if using bonded