Watertight Expansion Joints
A watertight expansion joint keeps water out of the space below while the structure moves — essential on plaza decks, split-slab and podium decks, parking structures and any joint over occupied space.
Where watertightness is critical
Anywhere a leak lands somewhere it shouldn’t: over lobbies, retail, car decks, basements and landscaped podiums. The joint must resist water under traffic and movement, resist fuel and UV, and prove its seal by test.
Key specifications
| Parameter | Best-in-class |
|---|---|
| Movement | 100% total (±50%), trafficable; up to ±250 mm on membrane systems |
| Watertightness | Verified by test (fire-hose / pressure); test certificate issued |
| Traffic / load | Direct traffic to ~300 kN class (DIN 1072) on armoured systems |
| Resistance | Fuel, oil and UV resistant elastomer |
How they work
A traffic-grade silicone or EPDM bellows/gland, mechanically retained in an aluminium frame and integrated with the deck waterproofing membrane, forms a continuous watertight seal that flexes with movement. Note that no manufacturer publishes a single hydrostatic head figure — performance is proven by watertightness test certificates, which Dseal supplies.
Frequently asked questions
What is a watertight expansion joint?
An expansion joint that keeps water from passing through it while the structure moves — used over occupied space, on decks, plazas and parking structures — with the seal verified by a watertightness test.
How is watertightness proven?
By test rather than a single pressure figure: manufacturers issue watertightness test certificates (e.g. fire-hose or pressure tests). Dseal provides a test certificate for its watertight systems.
© Dseal — building expansion joint systems, EPDM seals & membranes.