SJS: Seismic Joint System

EMSEAL SJS SeismicJointSystem

The Emseal SJS Seismic Joint System is a Watertight, Sound-Dampened Seismic and Large-Gap Joint System For Parking Decks, Car Parks, Stadiums and Floors.

The SJS System is comprised of silicone-and-impregnated-foam hybrid components that ensure watertightness, absorb sound, dampen vibration and offer uncomplicated installation.

Created from the latest evolution in the field-proven technology used by EMSEAL for over 30 years of sealing horizontal plane joints with impregnated foam sealants, the SJS is constructed from two horizontal joints pre-assembled in parallel adjacent to a heavy-duty extruded aluminum spline.

The spline acts as a receptor for attaching the surface-mounted traffic plates that bear vehicle and other loads.

The result is a system that offers features and benefits not found in alternative products intended for large, horizontal structural joint gaps.

Watertight – The tensionless silicone bellows are installed flush to the mounting height of the system and just below the cover plate ensuring watertightness at the traffic surface.  This eliminates the need for ineffective moisture barriers and secondary gutter systems. (SJS is also available specifically for watertight integration with split-slab buried waterproofing systems - see SJS-FP).

Sound Dampened – The flanking impregnated foam and silicone hybrid, dampens sound and shock effectively. When installed over EMCRETE, the result is arguably the quietest watertight cover plate system available.

Installs Rapidly – Using non-invasive anchoring, SJS eliminates drilling associated with hard metal-to-concrete connections as well as intrusive pins, anchors, screws, bolts or tracks, trays or rails. The system is locked to the joint faces by the backpressure of the foam and an epoxy adhesive, and by the weight of the assembly.

Self-Locating Cover Plate Screws – The center spline is a continuous receptor for the cover plate screws that are self-tapped into the anchor channel. This dramatically reduces the installation-related problems of locating self-centering, sliding ball devices and pantographs. The probability of screws being left out is eliminated ensuring proper anchoring.

Self-Locking, Vibration-Dampened Screws – Vibration in systems that rely on metal-to-metal connections and contact points is the main cause of screw loosening. SJS by EMSEAL minimizes vibration through the dampening action of the massive and continuous springs of impregnated foam along the entire length of the joint. In addition, 30 pounds of force is required to loosen the screws offering excellent screw tightness without the need for thread-lock compounds.

Field-Adjustable Plate Support – Concrete in new and retrofit applications is inevitably uneven across and along the joint. SJS is installed over a leveling-bed of EMCRETE material providing the ability to fine-tune the support of cover plate sections. This eliminates plate rocking and noise caused by unleveled plates. Systems that attach or utilize intrusive extruded rails to receive sliding ball and socket devices cannot be adjusted to eliminate unevenness across and down the length of the joint.

Continuity of Seal – All EMSEAL expansion joint systems feature continuity of seal through changes in plane and direction – an essential performance differentiator. Interlocking or continuous fabricated transitions for curbs, sidewalks, treads and risers and parapets for example, are available with SJS.

Fire Rating – SJS-FR1 & SJS-FR2 are designed for use in fire-rated applications. They have all the performance advantages of SJS with the addition of built in, UL-Certified, 1 or 2 hour fire rating respectively. 


  • For new construction and retrofit of old or failed joint systems.
  • For restoring watertightness to chronic leaking over occupied spaces.
  • Uniquely suited to joint openings designed for seismic separation of structural building elements.

Areas of application

  • parking decks
  • airport roadways
  • shopping centre bridge connectors
  • stadium concourses
  • stadium treads and risers

Note: for split-slab, plaza and podium decks see SJS-FP.

Performance & Selection:

Joint Sizes: For mean-temperature, structural-slab, joint sizes from 100mm up to 450mm (for special conditions or other sizes consult Allco). 
Movement Capability: 100% (+/-50%) of nominal material size.
Coverplates: Standard coverplate is 10mm (3/8-inch) shot-blasted aluminum or stainless steel. Other custom metals are available. Coverplate thicknesses can be customized to suit load and traffic expectations. Coverplate edge-chamfer available in standard or optional lowslope configurations (for customised options please consult Allco).
Fire Rating: SJS-FR1 & SJS-FR2 are designed for use in fire-rated applications. They have all the performance advantages of SJS with the addition of built in, UL-Certified, 1 or 2 hour fire rating respectively. 

Novotel Hotel, Christchurch

A weather tight, thermally and acoustically insulated, joint system capable of cycling through the engineered movement requirement and colour matched to the finished facade on three joints with a fire rating requirement on one. The movement requirements were both laterally and in shear.

Forte Apartments

The extension of a new parking deck onto an existing podium deck, with livable space below. The joint was designed to allow for significant movement (i.e. +/- 60mm), be suitable for vehicular traffic, safe for pedestrian traffic (no trip hazards), be watertight and offer thermal and acoustic insulation.


SJS: Seismic Joint System - Product Brochure


SJS: Seismic Joint System - Tech Data


SJS: Seismic Joint System - Install Data


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