Custom Rainscreen Joint Gaskets, Metal-Roof Closures & Cladding Seals for Roofing & Cladding

No, and no honest supplier claims otherwise: AAMA 501 (curtain-wall field and lab checks) and ASTM E330 (structural load by uniform static air pressure) evaluate the installed assembly, so the rating belongs to the tested assembly. What the part carries is its own documentation: an ASTM C864 or C509 class for the joint gasket, ASTM D1056 compression and density classes for the closure, durometer and compression data per the TDS, and lot-code traceability.

The part supports an assembly evaluated to those standards; H-O supplies the converted part and the paperwork, and the envelope designer owns the evaluation. [5]

EPDM is the economical outdoor default: ozone-, UV-, and weather-stable, covering the ordinary exterior temperature range, with cellular gaskets per ASTM C509 and dense gaskets per C864. Move to cellular silicone where a wider temperature window, a UL 94 flame class, or coastal salt governs the joint; silicone holds its compression recovery widest across temperature and is the step-up for the joints that see the widest swing.

For profiled roof closures the duty decides instead of the chemistry debate: closed-cell PE or PVC foam where a weathertight block is wanted, open-cell PU where the detail must vent. [2]

PVC closed-cell foam is the economical choice for joint seals behind the cladding line and for profiled lap and eave closures where the duty is a straightforward compression seal; compression and density classes are stated per ASTM D1056 on the TDS. Stay with EPDM foam or solid where continuous UV, ozone, and thermal movement drive the joint — dense EPDM per ASTM C864, cellular per C509 — and step up to cellular silicone only when temperature or a flame class governs.

Density still matters in either chemistry: a low-density foam shrinks and takes a set, opening a leak path. [6]

A steel anchor clip or cladding bracket bolted straight to structure becomes a metal-to-metal bridge that conducts heat and concentrates clamp load. A dense EPDM or elastomer pad in the clamp path carries the clamp load without becoming that bridge, and a closed-cell expanded-polyethylene strip takes up the tolerance where a cladding rail or bracket lands on structure; closed-cell PE classes are stated per ASTM D1056 on the TDS.

The framing’s own structural thermal break comes with the member — these pads and strips support it and never substitute for it. [6]

They sit on opposite sides of the panel, so the fit depends on the detail. Outside closures are installed at the lower edge (eave), on top of the eave trim but under the metal panel, and stop wind-driven rain from wicking back up under the panel. Inside closures are installed at the peak (ridge), on top of the metal panel but under the ridge cap. Both are to the exact panel rib profile. Getting the two swapped leaves a gap, so name the location on the detail and send the panel profile. [6]

Closed-cell foam (PE or PVC) blocks water and is the weathertight default where you want a tight seal at a lap or eave. Open-cell or reticulated foam is chosen deliberately where the detail must breathe: outside open-cell closures at the ridge let hot, moisture-laden air escape, and open-cell eave closures close the gap to pests and wind-driven rain while admitting fresh intake air as part of a natural ventilation path. Whichever you pick, density matters: a low-density foam shrinks and takes a set, so specify a density that resists shrink. [6]

With non-drying butyl seal tape in the seam and at every lap and penetration, plus profiled foam closures at the eave and ridge. Butyl (Poly-Seal® seal tape) stays ductile and conforms to the seam and lap geometry as the panels move with temperature, and its low water-vapor transmission is what keeps a standing seam weathertight over years. Die-cut and slit the butyl to the seam width and to the fastener and conduit penetrations; send the seam detail and the penetration list.

On any bonded seal, validate against the substrate, surface energy, temperature, exposure, dwell, pressure, prep, geometry, and assembly method.

A rainscreen manages water in a drained, back-ventilated cavity behind the cladding: the outer joint sheds most water, the cavity drains and equalizes pressure, and an inner gasket is the air-seal. So many rainscreen joints are meant to drain, not face-seal, and the gasket is a baffle or compression seal that lets water out while stopping wind-driven rain and blocking air at the inner line.

Treating a drained joint as a face seal, or leaving out the baffle, is a common leak path. Use ozone- and UV-stable EPDM or closed-cell sponge, to the joint, and name the drainage path on the detail. [1]

Usually compression set combined with a gap-based spec. A gasket sized to the nominal gap over-compresses at the tight end and loses contact at the loose end of framing tolerance, and over years of daily thermal cycling a gasket that takes a permanent set drops below its seal threshold with no visible failure. Specify the compression class against the real closure force and the tolerance band, not the average gap, pick a low-compression-set chemistry (silicone holds recovery widest across temperature), and leave recovery mid-range.

Compression set is tested per ASTM D395 for solids and ASTM D1056 methods for cellular grades. [6]

Only where the design or a code calls it. Many exterior cladding and roofing gaskets carry no flame requirement, and EPDM foam suffices. Where a standard, a fire-rated assembly, or the facade design does require a flame class on the gasket, specify a UL 94 V-0 silicone sponge (a V-0 flame-resistant silicone sponge, a BISCO® RS-series FR grade, or an equivalent V-0 grade) and state the class per the grade TDS.

The class belongs to the material grade, not to the assembly rating; write both correctly on the drawing. Fire-rated wall and perimeter-barrier assemblies are a separate scope, covered on the fire-life-safety sibling page.

H-O slits and converts sheet, roll, and profiled-foam stock to drawing: die-cut and kiss-cut joint and baffle gaskets, isolator pads, and profile-matched roof closures, with butyl slit to width. Extrusion is not one of our in-house processes; extruded gasket profiles are coordinated through a partner network with their own tooling lead times. Conversion runs in Winsted, Connecticut under an ISO 9001:2015 certified quality management system with material traceability and lot-code TDS records.