Engineered Threshold Systems
A purpose-engineered GFRP block, stainless leveling hardware, and project-specific shop drawings — so a zero-threshold sliding door lands within ±1 mm of a floor finish that doesn't exist yet.
The problem
On a 16-foot four-panel door, the aluminum track must sit within a millimeter of true across 192 inches — set months before the hardwood, porcelain, or terrazzo arrives. Wood shims, site-mixed grout, and wet-set plates all fix that height permanently on install day.
The installer sets elevation from an as-built slab that varies 3–5 mm, a specified floor thickness, and an adhesive bed nobody has mixed. Every upstream trade has to have executed exactly to spec.
Shims, grout, and wet-set plates are final the moment the door is set. Changing height means removing a door that often cost $40,000–150,000 — and the error surfaces only after flooring.
Shims swell, contract, rot, or crush. Grout cracks and settles under load. Galvanized plates lose their coating in curing concrete, and rust expansion moves the threshold millimeters.
Concrete conducts ~100× rigid foam. An uninterrupted slab from exterior grade to interior floor can cut envelope resistance up to 40% — cold floors, condensation, and mold at the threshold.
The system
Stainless steel and GFRP carry the load. EPS and injected polyurethane carry the thermal break. Threaded rod carries the precision. Nothing does two jobs — which is why nothing fails at the other's expense.
A closed-section vinyl-ester / ECR-glass composite, purpose-designed for permanent embedment in alkaline concrete: corrosion-immune, non-conductive, and dimensionally stable across every temperature the building will ever see. After final leveling, the cavity is injected with polyurethane foam — no voids, no moisture traps, and lateral support for the walls.
Workflow
The threshold is set to calculated elevation on install day and left adjustable. It's dialed to the actual finished floor on a second visit, then sealed monolithic — the door never leaves the opening.
The flooring installer works to the actual substrate. Variance from specified elevation is documented, not corrected. The cavity stays open, the block stays hollow, and the shop drawings keep every trade working to one reference.
Shop drawings
Not a generic reference detail. A coordination document for the exact door being installed, issued with every engagement.
Compatibility
The block is system-agnostic; the shop drawings are not. Each set is coordinated to the specific threshold profile, panel weight, and interlock configuration of the door being installed.