Norsound NOR820 Retro Fit Door Bottom Auto Drop Seal

Norsound NOR820 Retro Fit Door Bottom Auto Drop Seal | Aluminium | Various Lengths | 13.5 × 44mm

The NOR820 is a single-actuation automatic drop seal designed for retrofit installation to the bottom edge of acoustic timber or metal doorsets. When the door closes, the actuator contacts the door stop or frame and drives the seal carrier downward, closing the gap between the door bottom and the floor. When the door opens, the carrier retracts, allowing the door to swing freely without the seal dragging across the floor surface. This automatic action ensures the gap is sealed consistently on every close without requiring manual adjustment. The seal is screw-fixed to the bottom face of the door leaf and does not require routing or removal of door core material.

The NOR820 is manufactured from aluminium with a PVC gasket and supplied in a satin silver finish with a grey gasket. The housing profile is 13.5 × 44mm. Maximum gap coverage is 12mm. Standard lengths run from 400mm to 1200mm in 100mm increments, with a cutback of 125mm (130mm on the 400mm length) to clear door furniture. The seal meets smoke requirements to BS 8214 and is acoustically tested in accordance with BS EN ISO 10140-2. It is recommended by door manufacturers including Falcon Strebord, Halspan, and Flamebreak for use with acoustic and fire-rated doorsets.

Applications

• Acoustic timber doorsets — retrofit to the bottom face of the door leaf where the gap between the door bottom and floor finish requires sealing for acoustic performance. The automatic drop mechanism ensures the seal engages on every close without manual intervention, making it appropriate for high-traffic doors where consistent sealing is required. Select the length closest to the door leaf width, accounting for the cutback dimension at each end to clear hinges or other door furniture.
• Fire-rated and smoke-control doorsets — the NOR820 meets smoke requirements to BS 8214, making it suitable for use on fire-rated doorsets where smoke sealing at the door bottom is required. The screw-fixed installation does not compromise the door core, preserving the fire resistance of the doorset. Verify compatibility with the specific doorset certification before installation.
• Metal doorsets — the screw-fixed aluminium housing is compatible with both timber and metal door leaves. For metal doors, use appropriate fixings for the door material and thickness.

Product Benefits

• Single-actuation automatic drop mechanism — consistent sealing on every close. The actuator engages the door stop on closing, driving the seal carrier down to close the floor gap automatically. The mechanism retracts on opening, preventing the seal from dragging across the floor. This eliminates the inconsistency of manual or wipe seals on high-traffic doors and ensures the acoustic and smoke seal is engaged every time the door is closed.
• Screw-fixed to door face — no routing required. The NOR820 is surface-mounted to the bottom face of the door leaf using screw fixings, without requiring any material to be removed from the door core. This preserves the structural and fire integrity of the door and makes installation straightforward on existing doorsets without specialist tooling.
• Smoke tested to BS 8214 — acoustic tested to BS EN ISO 10140-2. The NOR820 meets smoke requirements under BS 8214 and has been acoustically tested in accordance with BS EN ISO 10140-2, making it suitable for use on doorsets where both smoke control and acoustic performance are required.
• Nine standard lengths — 400mm to 1200mm. Available in 100mm increments from 400mm to 1200mm, covering the full range of standard door leaf widths. The 125mm cutback (130mm on the 400mm length) accommodates standard door furniture positions without modification.
• Aluminium housing, satin silver finish. The 13.5 × 44mm aluminium profile is supplied in satin silver with a grey PVC gasket, providing a low-profile, durable finish compatible with standard commercial and residential doorset aesthetics.

Installation

Measure the door leaf width and select the appropriate seal length, ensuring the cutback dimension clears all door furniture (hinges, latches, and closers) at both ends. The seal should not extend beyond the door leaf width.

Position the NOR820 centrally on the bottom face of the door leaf with the actuator pin aligned to contact the door stop or frame strike point on closing. Mark and drill fixing holes. Screw-fix the housing to the door face using appropriate fixings for the door material.

Close the door and check that the actuator engages the door stop cleanly and the seal carrier drops to make full contact with the floor across the width of the seal. Adjust the actuator position if required to achieve consistent engagement. Check that the carrier retracts fully on opening and does not drag across the floor surface.

Seal the perimeter of the door frame — head, jamb, and threshold — with compatible Norsound seals to complete the acoustic and smoke barrier around the full doorset.

The Technical Details