Expansion Joints and Pre-Compressed Sealants

Watertight Joint System for Decks and Below-Grade Walls

Tech Data

Install Data


Guide Spec





Installations: Concrete.Metal

en español


DSM SYSTEM from EMSEAL. Parking, Stadium, etc. Expansion Joint.  Watertight, Traffice-Durable, Acrylic-Impregnated, Precompressed Sealant.
DSM SYSTEM in stadium treads and risers retrofit of structural expansion joints.  DSM from EMSEAL used instead of caulk-and-backerrod in precast building component connections.

• Watertight
• Tensionless silicone bellows
• Traffic durable
• Rapid installation--new or retrofit
Non-invasive anchoring
• Staged installation preserves traffic flow
• Joint-face adhered

parking decks/car parks

• sidewalks
• decks
• airport aprons
• mall bridge connectors

positive-side, below-grade foundation/tunnel wall joints.
• stair towers
• runways
• arenas
• perimeter joints
• roadways
• For concrete substrates
• For metal substrates where demolition and removal of existing embedded metal angles is not feasible or affordable.
• Lasting replacement of tee-to-tee caulk joints in precast-concrete parking decks and stadiums.

Standard Sizes
1/2" to 4" (12 - 100mm)

Note: Sizes under 1 1/2" (40mm) are manufactured with a single bellows. Larger sizes incorporate multiple bellows. (Above 4" (100mm), see SJS SYSTEM or contact EMSEAL)

Movement Capability
Up to 100% Total (+50% and -50% of nominal supplied size)
(For joint openings 4-inches (100mm) and larger, where an integral coverplate is preferred, consider SJS SYSTEM)

Standard color is gray (for other colors contact EMSEAL)

Product Description

The DSM SYSTEM builds on a track record of over 30 years of sealing horizontal plane and below-grade expansion joints with impregnated foam sealants.

The system is comprised of:
1) Pre-compressed, silicone-and-impregnated-foam hybrid installed into...
2) field-applied epoxy adhesive on the joint faces; with the silicone bellows locked to the joint faces with...
3) a silicone sealant band (see Figure 1).

The DSM SYSTEM features an innovation in sealant technology in the form of a innovative, microsphere-modified acrylic adhesive infused into the cellular foam base material.

DSM features sealing performance significantly greater than any impregnated pre-compressed predecessor. In addition, it is odorless, clean handling, UV stable, non-staining, and features low temperature flexibility not previously available in asphalt, wax, or isobutylene-based predecessors.

The result is extension of the usability of the product to applications where asphalt or wax-based predecessors did not work well under conditions of thermal shock (rapid opening and closing of joints during large temperature swings). These applications include joint-face adhered installations on top decks as well as intermediate decks.

The DSM SYSTEM has an extensive track record of service throughout the world. It has been widely adopted as the replacement for virtually all applications where older, inflated-type systems were once favored.  In contrast to the inflated seals, the DSM SYSTEM remains in compression over its life.  As a result it is not subject to failure due to excessive tension on the bond line.

Features Explained

Watertight—the tensionless silicone bellows is installed just below the deck surface. This ensures watertightness is achieved at the deck surface.

Non-Invasive Anchoring—there are no hard metal-to-concrete connections in the system. This includes embedded pins, anchors, screws, bolts or tracks, trays or rails. The system is locked to the joint faces by means of the 1) backpressure of the foam; 2) the epoxy adhesive, and 3) the injected silicone sealant band at the joint face to foam and silicone bellows interface.

Continuity of Seal—as in all EMSEAL expansion joint systems, continuity of seal through changes in plane and direction is an essential performance differentiator. Details for watertight, field-fabricated transitions from deck to wall, at curbs, sidewalks, parapets, tees, and crosses are available with the DSM SYSTEM.

Aesthetics & Versatility—Standard color is gray (other colors available), uniform bellows appearance, double sealing, fuel resistance, and an enhanced ability to handle variations in joint size are among other system features.


DSM SYSTEM in Typical Concrete Substrates:

DSM SYSTEM in Existing metal angle substrates:

Performance Limitations

• Substrates must be parallel, plumb and capable of resisting approx. 2.5 psi backpressure from the foam.

• Fuel Resistance: Silicone sealant is not degraded by contact with fuel. Some swelling of the material will normally occur, but it will return to its original shape upon evaporation of the fuel.


• DSM is produced by infusing a cellular foam base material with EMSEAL’s microsphere-modified acrylic impregnation and is coated with a highway-grade silicone. DSM-DS is also available which is built with the silicone coating on the top and bottom surface.

• The silicone external facing is factory applied to the foam at a width greater than maximum joint extension and is cured before final compression.

• Silicone application and curing takes place in a factory-controlled environment. In contrast to field applied liquid sealant and backer rod installations, no movement takes place during curing that can cause deformation or stresses in the material.

• When compressed, a bellows is created in the coating. As joint movement occurs the bellows simply folds and unfolds free of tension on the bond line, and virtually free of tensile stresses in the silicone material.

• The foam provides a resilient backing to the silicone coating, making the system capable of resisting reasonable transient point loads.

• DSM SYSTEM is supplied in 6.56 LF (2m) shrink-wrapped lengths (sticks). It is pre-compressed to less than the joint size for easy insertion. After removal from the shrink-wrap and hard board restraining packaging, it expands gradually.

Click here to see who's using DSM?

Transitions and Terminations:

Universal 90's

(US Patent 9,200,437
Patent Pending)

Custom 90's 
Patent Pending)

U-90's are factory-made transition pieces that ensure continuity-of-seal where expansion joints change plane or direction.

DSM is manufactured in straight-run sticks which can be joined in the field to EMSEAL’s patented and patent-pending "Universal-90" transitions.

These factory-fabricated single-piece 90-degree units have a 12-inch long leg and a 6-inch vertical piece on each side of the elbow. Universal-90 transition are symmetrically coated on both faces allowing them to be installed as an inside corner or as an outside corner.

In addition to guaranteeing watertightness, EMSEAL’s "Universal-90's" allow for much faster and secure installation by eliminating field cutting or notching and bending, at angles.

Custom-90's (patent pending), coated on just the weather-facing faces, are also available when field conditions and measurements are known up front.

Consult EMSEAL.

(More on Universal-90's


Universal-90 Upturn Transition

Universal-90 Flipped-Over as Downturn Transition


EMSEAL JOINT SYSTEMS LTD. 25 Bridle Lane, Westborough, MA 01581
EMSEAL LLC. 120 Carrier Drive, Toronto, ON M9W 5R1



1-800-526-8365 -- 508-836-0280 --  techinfo@emseal.com -- Fax: 508-836-0281

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