A contractor bidding a 400-meter track in the Gulf has to commit to a system before the first container is booked. Spray coat, sandwich, or full pour. Each has a different material stack, a different per-square-meter mass, a different labor profile, and a different total tonnage that will eventually be loaded into a 20-foot container at the port. Choosing by familiarity rather than by engineering is one of the most expensive mistakes in international track installation.
The Three Systems in Plain Language
Spray coat, sandwich, and full pour are not marketing labels. They describe physically different layered constructions with different resin-to-rubber ratios, different thicknesses, and different performance envelopes.
Spray coat, often called the breathable system, is built around a base of large-particle SBR rubber bound with single-component polyurethane, finished with a thin sprayed coat of PU resin into which fine EPDM granules are air-atomized. Total thickness sits near 13 millimeters. The open pore structure lets the slab breathe; it is the most forgiving system on humid sites and the lightest of the three on a per-square-meter basis.
Sandwich, the workhorse of international school and municipal projects, places a thicker SBR base under a closed-cell PU self-leveling layer, with EPDM granules broadcast onto the surface and partially reclaimed. Thickness runs 13 to 14 millimeters. The structure is non-permeable, so a sound asphalt base and proper drainage become non-negotiable.
Full pour, sometimes called solid PU, replaces most of the SBR with stacked layers of two-component polyurethane elastomer and embedded rubber, then caps with a dense broadcast of virgin EPDM. Thickness lands between 13 and 15 millimeters, and the resin-to-rubber ratio is the highest of the three. Full pour is what world-class competition venues typically specify.
Comparing the Three Systems Across the Variables That Matter
The table below summarizes the engineering and commercial variables that drive real procurement decisions on international projects.
| Variable | Spray coat (breathable) | Sandwich | Full pour (solid PU) |
|---|---|---|---|
| Total thickness | Around 13 mm | 13 to 14 mm | 13 to 15 mm |
| Permeability | Permeable | Non-permeable | Non-permeable |
| Net mass per square meter | Around 10.75 to 11.40 kg | Around 15.45 to 16.05 kg | Around 13.65 to 16.15 kg |
| EPDM surface dosage (retained) | About 1.20 kg | About 2.80 kg | Around 3.00 kg |
| PU resin intensity | Lowest | Moderate | Highest |
| Best climate fit | Humid, monsoon | Mixed, temperate | Hot, dry, high-spec |
| Container profile (per 7,500 m²) | Lowest tonnage, most pallets | Heaviest, pallet-bound | Liquid-heavy, fewer pallets |
| Tolerance for marginal base | Highest | Lower | Lowest |
The numbers are approximate because real recipes vary by manufacturer, but the rank order is stable: spray coat is the lightest and most forgiving, full pour is the heaviest in liquid resin and the most demanding on substrate quality, sandwich sits between them on both axes.
Matching the System to the Project
Three questions usually decide the system before any spreadsheet is opened.
What climate will the track live in? Permeable spray coat tolerates the most moisture; full pour on a poor base in a humid region invites osmotic blistering and edge shrinkage. On a hot, dry site with a well-engineered asphalt base, full pour delivers the highest spike resistance and the longest service life.
What certification level is required? International federation-class venues increasingly default to full pour. School and municipal installations with a strong durability requirement commonly accept sandwich. Community and recreational tracks often run spray coat to keep budgets in range without sacrificing surface comfort.
What is the substrate doing for us? Concrete bases, particularly new ones, carry internal moisture. Spray coat breathes; sandwich and full pour demand a moisture-mitigation plan including calcium chloride or relative humidity testing and a properly specified epoxy moisture barrier where needed.
How Container Math Changes the Decision
International track projects live or die by containerized logistics. Spray coat is dense in SBR and light in resin; sandwich is heavy across the stack; full pour skews heavily into liquid drums. Spray coat typically loads into a moderate number of 20-foot containers, sandwich approaches the 20.4-ton payload limit per TEU with the maximum double-stack of pallets, and full pour requires careful drum-count planning because every extra kilogram of liquid PU pushes the container closer to the road-weight ceiling.
Estimators who treat container packing as an afterthought routinely discover that the cheapest system on paper is the most expensive one once port-of-destination handling and inland trucking are added. The procurement conversation should include logistics from day one, not after the purchase order is signed.
FAQ
Q1: Is full pour always the better system?
Not always. Full pour is the highest-spec option, but its performance depends on substrate quality, climate, and installation discipline. On a marginal base in a humid climate, a properly executed sandwich system outperforms a poorly installed full pour every time. The right system is the one matched to site conditions and project requirements, not the one with the most resin in the recipe.
Q2: Can a system be upgraded from spray coat to sandwich later?
Resurfacing a spray coat with a sandwich overlay is technically possible when the existing base is sound, but it requires profiling the old surface, re-priming, and rebuilding thickness tolerances. In practice, owners usually decide the system at design and live with it for the life of the surface; switching systems mid-life is rare.
Q3: Can EpdmSports supply material for all three systems?
Yes. EpdmSports supplies EPDM granules, SBR base rubber, and a full PU resin range (primer, adhesive, pore sealer, self-leveling elastomer, and aliphatic line paint) for spray coat, sandwich, and full pour installations. Send the project specifications and the technical team will propose the matched material configuration with BOQ support.
Choosing between running track systems for a new project? Share your drawings, climate profile, and certification target, and the EpdmSports team will return a side-by-side material and container comparison, no obligation.