Norsound NOR820 Retrofit Automatic Drop Seal – 44 × 13.5mm is a surface-mounted automatic door-bottom seal designed to improve acoustic and cold-smoke sealing without routing a groove into the door leaf.
The slim aluminium housing is screw-fixed to the face of an existing timber or metal door. A clip-on satin-silver cover plate conceals the fixings and provides a neat finished appearance.
As the door closes, a single mechanical actuator activates the internal mechanism and lowers the grey PVC gasket onto the finished floor, sill or threshold plate.
When the door opens, the gasket retracts into the aluminium housing, helping prevent it from dragging continuously across the floor.
The NOR820 is intended to close the otherwise open gap beneath an acoustic timber or metal doorset.
It can help:
The NOR820 treats only the bottom of the door. Suitable seals are normally also required around the door head and jambs.
The NOR820 is surface-mounted rather than rebated into the door.
This means that installation does not normally require:
This makes the NOR820 particularly useful for:
The seal contains a mechanically operated drop mechanism.
When the door closes, the actuator contacts its corresponding frame-mounted contact point and activates the seal.
The grey PVC gasket lowers until it contacts the finished floor or threshold.
When the door begins to open, the pressure on the actuator is released and the gasket retracts into the housing.
The NOR820 requires:
The NOR820 uses one actuator to operate the drop mechanism.
Norseal describes the actuator as a clip-in component that can be adjusted by hand, allowing the amount of gasket travel to be set after installation.
The drop should be adjusted so that the gasket makes light and continuous contact with the threshold when the door closes.
Excessive adjustment can:
The internal mechanism is designed to lower the gasket across the width of the door and accommodate limited variation in the threshold level.
This can help maintain contact where the floor is slightly sloped from one side of the opening to the other.
The seal cannot compensate for:
Where the floor is unsuitable, a smooth threshold plate may be required.
The NOR820 provides maximum gap coverage of 12mm.
The actual threshold gap permitted on a particular door may be lower because of:
The finished gap should be measured at several positions across the door opening before selecting and installing the seal.
The NOR820 has been acoustically tested in accordance with BS EN ISO 10140-2.
The individual product does not have a universal standalone decibel rating.
Any numerical sound-reduction result depends on the complete tested door assembly, including:
A drop seal should therefore be treated as one component within a complete acoustic doorset.
Norseal states that the NOR820 meets the smoke requirements of BS 8214.
Associated smoke-seal documentation also refers to testing of automatic threshold seals in accordance with BS 476-31.1.
For effective smoke control, the PVC gasket must make continuous contact with a firm threshold surface when the door closes.
The complete doorset may also require:
The NOR820 is face-fixed and does not normally require removal of door-core material.
Norseal states that fitting the NOR820 is not detrimental to the door’s fire-resistance performance where the seal is surface-mounted without removing core material.
This does not mean that the NOR820 independently provides a fire-resistance rating.
Before installation on a fire door, confirm:
The current Norseal product page links to CF629 documentation. The linked certificate revision states a validity date ending on 13 January 2024, so current certification status should be confirmed before relying on that certificate for a new specification.
The NOR820 is designed for surface fixing to:
The door face must provide a stable surface capable of accepting the supplied screw fixings.
The NOR820 can be fitted to either the inward or outward face of a suitable door.
The measurement and actuator contact arrangement differ depending on which face is selected.
The manufacturer’s fitting guide specifies:
The correct measurement method must be selected before the seal or cover plate is cut.
The NOR820 includes a satin-silver aluminium cover plate.
The cover plate:
Both the seal body and cover plate must be shortened to the same finished length.
The retractable sealing element is manufactured from grey PVC.
The gasket provides:
Keep the gasket free from:
The NOR820 can close against a suitable:
A threshold plate may improve sealing where the existing floor is:
Complete the final actuator adjustment only after the finished floor or threshold plate has been installed.
The NOR820 is available in the following standard lengths:
Select the closest suitable length that can be shortened to the required measurement without exceeding its cut-back allowance.
The NOR820 can be shortened from its non-actuator end.
The manufacturer states:
Always check the individual product label before cutting.
Cutting beyond the permitted limit can damage the internal mechanism and prevent the seal from operating.
The NOR820 is a surface-mounted retrofit seal.
The NOR810 is a concealed rebated seal installed within a 14 × 35mm groove along the bottom edge of the door.
Choose the NOR820 where:
Choose a rebated seal only where the door construction and doorset evidence permit the necessary machining.
The NOR820 can be used within suitable doorsets in:
Before ordering, confirm:
Norsound NOR820 Retrofit Automatic Drop Seal is a screw-fixed, surface-mounted automatic threshold seal with a satin-silver aluminium housing, grey PVC gasket and single mechanical actuator.
| Product Name | Norsound NOR820 Retrofit Automatic Drop Seal – 44 × 13.5mm |
| Brand | Norsound by Norseal |
| Product Reference | NOR820 |
| Product Type | Surface-mounted retrofit automatic acoustic and smoke door-bottom seal |
| Application | Bottom edge of acoustic timber or metal doorsets |
| Installation Method | Face-fixed using screws; no routed mortise required |
| Installation Faces | Suitable inward- or outward-face installation, subject to the appropriate measuring and actuator arrangement |
| Profile Height | 44mm |
| Profile Projection | 13.5mm |
| Maximum Gap Coverage | 12mm |
| Actuation | Single mechanical actuator |
| Actuator Type | Clip-in adjustable actuator |
| Adjustment | Actuator can be adjusted by hand to control gasket travel |
| Self-Levelling Mechanism | Yes, for limited variation in the threshold level |
| Power Requirement | None — mechanically operated |
| Housing Material | Aluminium |
| Cover Plate | Clip-on aluminium cover plate concealing the screw fixings |
| Housing Finish | Satin Silver |
| Gasket Material | PVC |
| Gasket Colour | Grey |
| Smoke Performance | Meets the smoke requirements of BS 8214 |
| Associated Smoke-Test Standard | BS 476-31.1 is referenced by the linked smoke-seal certification documentation |
| Acoustic Test Standard | BS EN ISO 10140-2 |
| Fire-Door Application | Surface installation is stated not to be detrimental to fire resistance where no door-core material is removed, subject to the doorset evidence |
| Certification Documentation | The manufacturer currently links CF629 documentation; the linked revision states validity to 13 January 2024, so current validity should be confirmed |
| Durability Documentation | Manufacturer cycle-test documentation is available; current specification directories report testing to 200,000 cycles |
| Standard Lengths | 400, 500, 600, 700, 800, 900, 1000, 1100 and 1200mm |
| Maximum Standard Length | 1200mm |
| General Cut-Back | 125mm |
| 400mm Cut-Back | Maximum 130mm |
| Fixings | Screw fixings supplied |
| Standalone Acoustic Rating? | No — performance depends on the complete tested door assembly |
| Standalone Fire Rating? | No — the NOR820 does not independently provide a fire-resistance period |
| Length | Profile Size | Finish | Maximum Cut-Back | Product Code |
|---|---|---|---|---|
| 400mm | 44 × 13.5mm | Satin Silver / Grey gasket | 130mm | NOR820/0400/S |
| 500mm | 44 × 13.5mm | Satin Silver / Grey gasket | 125mm | NOR820/0500/S |
| 600mm | 44 × 13.5mm | Satin Silver / Grey gasket | 125mm | NOR820/0600/S |
| 700mm | 44 × 13.5mm | Satin Silver / Grey gasket | 125mm | NOR820/0700/S |
| 800mm | 44 × 13.5mm | Satin Silver / Grey gasket | 125mm | NOR820/0800/S |
| 900mm | 44 × 13.5mm | Satin Silver / Grey gasket | 125mm | NOR820/0900/S |
| 1000mm | 44 × 13.5mm | Satin Silver / Grey gasket | 125mm | NOR820/1000/S |
| 1100mm | 44 × 13.5mm | Satin Silver / Grey gasket | 125mm | NOR820/1100/S |
| 1200mm | 44 × 13.5mm | Satin Silver / Grey gasket | 125mm | NOR820/1200/S |
| Supplied Length | Maximum Cut-Back | Approximate Minimum Finished Length |
|---|---|---|
| 400mm | 130mm | 270mm |
| 500mm | 125mm | 375mm |
| 600mm | 125mm | 475mm |
| 700mm | 125mm | 575mm |
| 800mm | 125mm | 675mm |
| 900mm | 125mm | 775mm |
| 1000mm | 125mm | 875mm |
| 1100mm | 125mm | 975mm |
| 1200mm | 125mm | 1075mm |
The approximate minimum finished lengths are calculated from the published maximum cut-back allowances. Always check the individual product label before cutting.
Where the NOR820 is fitted to the inside face of the door:
Where the NOR820 is fitted to the outside face of the door:
The NOR820 has been acoustically tested in accordance with BS EN ISO 10140-2.
No universal standalone decibel rating should be assigned to the individual seal.
Final sound reduction depends on:
The NOR820 meets the smoke requirements of BS 8214 within suitable complete doorset arrangements.
The gasket must make continuous threshold contact when the door is closed.
Compatible smoke seals will normally also be required around the door head and jambs.
The NOR820 does not contain intumescent material and does not provide an independent fire-resistance period.
Its principal fire-door advantage is that it can be face-fixed without removing core material.
Before installation on a fire door:
Store the NOR820:
Do not allow debris to enter the internal drop mechanism.
Norsound NOR820 Retrofit Automatic Drop Seal is face-fixed to the bottom of a timber or metal door using screws.
The seal may be installed on the inward or outward face of a suitable door. The measuring method differs according to the selected face.
No routed mortise is required.
The fitting kit includes:
Check all components before starting installation.
Inspect the door, frame and threshold.
Confirm that:
Do not drill into concealed wiring, glazing, reinforcement or other door components.
Decide whether the NOR820 will be fitted to the:
The chosen position determines the required finished seal length.
Measure the clear distance between the two door stops.
Record this dimension as X.
Calculate the required seal length using:
L = X − 7mm
For example:
Record measurement L for cutting.
Identify the final position of the actuator contact screw or plate.
Measure between that contact position and the hanging-side edge of the door.
Record this dimension as X.
Calculate the required seal length using:
L = X − 2mm
For example:
Record measurement L for cutting.
Compare the required finished length with the supplied product.
The permitted maximum cut-back is:
Check the individual product label before cutting.
Do not shorten the seal beyond the marked limit.
Identify the end containing the actuator mechanism.
All measurements should be taken from the actuator end.
The excess material is removed from the opposite end.
Before cutting, reconfirm:
Do not cut through the actuator mechanism.
Measure dimension L from the actuator end.
Mark the finished length on both:
Both components must finish at the same length.
Check the marks before cutting.
Unclip or slide the aluminium cover plate away from the main seal body.
Set it aside carefully to protect the satin-silver finish.
Do not bend or twist the cover profile.
Withdraw or move the flexible PVC gasket away from the cutting line.
Move enough gasket clear so that it cannot be damaged by the saw.
Do not:
Support the seal body and cover plate securely.
Cut both aluminium sections squarely at the marked position using a fine-tooth saw.
After cutting:
Rough edges may cause the cover plate or gasket to catch during operation.
Return the PVC gasket to its normal position within the inner carrier.
Trim the excess gasket cleanly using a sharp knife.
Do not stretch the gasket while trimming, as it may retract and finish too short.
Confirm that it remains:
Hold the seal against the selected door face near the bottom edge.
Position it so that:
Do not position the body so low that the gasket drags while the door is open.
With the seal held level in its final position, mark the screw-fixing holes onto the door face.
Check that each fixing enters suitable door material.
For metal doors, use fixing methods appropriate to the door construction.
Do not place screws where they could damage:
Remove the seal and drill suitable pilot holes at the marked positions.
Select the drill size according to:
Remove all drilling debris before fixing the seal.
Return the NOR820 to its marked position and secure it using the supplied screws.
Tighten the screws evenly.
Do not overtighten them, as this can:
Check that the body remains level.
Fit the supplied actuator plate, contact screw or corresponding frame component in the position shown by the manufacturer’s guide.
The contact component must align with the seal actuator as the door closes.
For an outside-face installation, its position forms part of the original measurement used to calculate the finished seal length.
Check that:
Fit the actuator stick and any required distance pieces in accordance with the manufacturer’s instructions.
The distance pieces allow the actuator contact position to be adjusted for the door and frame arrangement.
Make sure the actuator is securely clipped into position before testing the door.
Clip the satin-silver aluminium cover plate over the fixed seal body.
Check that:
Close the door slowly while observing the gasket.
The NOR820 should:
Adjust the clip-in actuator progressively by hand.
Open and close the door after each small adjustment.
Continue until the gasket makes light and continuous threshold contact when the door is fully closed.
Do not over-adjust the actuator.
Close the door and inspect the gasket across the complete opening.
Confirm that:
Where the floor is too uneven or compressible, install a suitable threshold plate rather than forcing excessive drop from the mechanism.
Operate the door several times.
Confirm that:
Where a threshold plate is required, install it before completing the final actuator adjustment.
The threshold plate should:
Readjust the NOR820 after completing the final flooring and threshold installation.
The NOR820 treats only the threshold gap.
Suitable seals will normally also be required around the:
Use the complete acoustic or smoke-sealing arrangement specified for the doorset.
Inspect and operate the NOR820 regularly as part of the door-maintenance programme.
Check for:
Clean the gasket and threshold using a soft cloth and a suitable mild cleaning product.
Do not apply unapproved oil, grease or lubricant to the internal mechanism.
Correct measuring, cutting, positioning, fixing and actuator adjustment are essential to the operation of the NOR820.
The product does not independently create an acoustically rated, smoke-control or fire-resisting door.
Final performance depends on:
For fire-resisting or certified doorsets, install the NOR820 only in accordance with the applicable test evidence, assessment and door-manufacturer instructions.
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