Norsound NOR755 Acoustic Perimeter Seal – 26.5 × 5mm is a surface-mounted, screw-fixed acoustic door seal designed for installation around the head and jambs of suitable doorsets.
The profile combines a rigid satin-silver aluminium carrier with an ultra-soft grey silicone bubble gasket.
When the door closes, the silicone gasket compresses gently against the opposing door surface to help close the operating gap between the door leaf and frame.
This helps restrict:
The NOR755 is available in two standard lengths:
Both options have a satin-silver aluminium carrier and grey silicone gasket.
The NOR755 is designed for installation around:
It is particularly useful where an existing door requires an acoustic upgrade without routing a groove into the door leaf or frame.
The surface-mounted design can be used within suitable:
The product treats the head and jambs only. A compatible automatic drop seal or threshold seal is normally required beneath the door.
The aluminium carrier is fixed to the surface of the door stop using screws.
The soft silicone bubble projects towards the door leaf.
As the door reaches its closed position, the silicone gasket compresses between the door and stop.
Correct compression helps form a continuous flexible seal around the three-sided door perimeter.
The gasket should:
A recommended gap tolerance of approximately 3mm to 4mm is commonly specified for the NOR755 installation arrangement.
The precise permitted gap may also be controlled by:
The NOR755 should not be used to compensate for a severely warped door, loose hinges or large and inconsistent perimeter gaps.
The NOR755 has been acoustically tested in accordance with:
BS EN ISO 10140-2
The soft silicone gasket helps reduce sound transmission by closing the direct air path between the door leaf and frame.
The individual seal does not have a universal standalone decibel rating.
Final acoustic performance depends on the complete doorset, including:
Any numerical sound-reduction rating must be attributed to the complete tested door assembly rather than the NOR755 profile alone.
The flexible sealing element is manufactured from silicone.
Its soft bubble profile allows the gasket to compress against the door while minimising the effect on opening and closing forces.
The silicone gasket provides:
The gasket should not be completely flattened when the door closes.
Excessive compression can:
The NOR755 uses a rigid aluminium carrier with a satin-silver appearance.
The carrier provides:
A decorative cover strip conceals the screw fixings after installation.
This provides a cleaner appearance and helps prevent casual access to the fixings.
The NOR755 is fixed directly to the surface of the door stop.
Unlike a kerf-fit or rebated seal, it does not normally require:
This makes it suitable for upgrading existing doors where surface-mounted hardware is acceptable.
The door stop must be:
The NOR755 can provide a practical acoustic upgrade to an existing door because the aluminium carrier is surface mounted.
This can reduce installation work where:
The existing door must still provide suitable mass, alignment and construction for the required acoustic performance.
A perimeter seal cannot compensate for a lightweight or poorly fitted door leaf.
By restricting airflow through the perimeter gaps, the silicone gasket can also act as a draught seal.
This may help:
The NOR755 is not a substitute for a complete building-air-tightness or thermal-insulation system.
A flexible perimeter gasket may help restrict airflow around a closed door.
However, the current Norseal NOR755 product page publishes acoustic testing but does not state a specific NOR755 smoke-test standard.
Do not describe the NOR755 as a certified smoke seal unless the current project evidence confirms:
Where certified smoke control is required, use only the complete tested or assessed doorset specification.
The NOR755 is an acoustic perimeter seal and does not contain an intumescent fire-sealing element.
It does not independently provide an FD30, FD60 or other fire-resistance classification.
Where installation is proposed on a fire-resisting doorset:
Surface mounting reduces the need to remove door-core material, but approval for the complete arrangement must still be confirmed.
The NOR755 treats the door head and jambs but does not seal beneath the door.
It can be combined with a suitable door-bottom product such as:
A threshold plate may also be required where the finished floor is uneven, carpeted or unsuitable for direct gasket contact.
The available lengths are:
Both lengths can be shortened to suit the installation.
The number of profiles required depends on:
A standard single-leaf door normally requires sealing along:
A common arrangement may use:
This is only a general example.
Measure the actual frame before ordering, as tall or wide doors may require a different combination.
The NOR755 is supplied with:
No alternative carrier or gasket colours are included within this product range.
The NOR755 and NOR710 are both acoustic perimeter seals, but they use different fixing and gasket systems.
| Feature | NOR755 | NOR710 |
|---|---|---|
| Fixing | Screw-fixed | Self-adhesive |
| Carrier | Aluminium | Rigid PVC |
| Sealing element | Soft silicone bubble | Flexible PVC blades |
| Profile size | 26.5 × 5mm | 10 × 10.2mm |
| Installation | Surface mounted to the stop | Surface mounted using adhesive |
The correct product should be selected according to the door design, required fixing method and supporting doorset evidence.
Before ordering, confirm:
Norsound NOR755 Acoustic Perimeter Seal is a surface-mounted, screw-fixed aluminium profile incorporating a soft grey silicone compression gasket.
| Product Name | Norsound NOR755 Acoustic Perimeter Seal – 26.5 × 5mm |
| Brand | Norsound by Norseal |
| Product Reference | NOR755 |
| Product Type | Surface-mounted acoustic perimeter compression seal |
| Application | Around the head and jambs of suitable acoustic doorsets |
| Primary Function | Reduction of airborne sound and uncontrolled airflow through door-perimeter gaps |
| Fixing Method | Screw fixed to the surface of the door stop |
| Installation Type | Surface mounted; no routed groove normally required |
| Nominal Profile Height | 26.5mm |
| Nominal Profile Projection | 5mm |
| Profile Size | 26.5 × 5mm |
| Recommended Gap Tolerance | Approximately 3mm to 4mm, subject to the doorset specification |
| Carrier Material | Aluminium |
| Carrier Finish | Satin Silver / satin anodised aluminium appearance |
| Gasket Material | Silicone |
| Gasket Profile | Ultra-soft compression bubble |
| Gasket Colour | Grey |
| Fixing Cover | Decorative cover strip concealing the screw fixings |
| Available Lengths | 1000mm and 2100mm |
| Acoustic Test Standard | BS EN ISO 10140-2 |
| Smoke-Test Standard | No specific smoke-test standard is stated on the current official NOR755 product page |
| Intumescent Material | No — the NOR755 does not replace a required intumescent fire-door seal |
| Electrical Requirement | None |
| Standalone Acoustic Rating? | No — acoustic performance depends on the complete tested doorset |
| Standalone Smoke Classification? | No classification should be stated without current supporting evidence |
| Standalone Fire Rating? | No — the profile does not independently provide a fire-resistance period |
| Length | Profile Size | Finish | Gasket | Product Code |
|---|---|---|---|---|
| 1000mm | 26.5 × 5mm | Satin Silver | Grey silicone | NOR755/1000 |
| 2100mm | 26.5 × 5mm | Satin Silver | Grey silicone | NOR755/2100 |
The stocked codes use the following format:
NOR755 / Supplied Length
For example:
The finish and gasket colour are fixed and therefore do not appear as separate colour suffixes within the current product codes.
Choose the supplied lengths according to the measured door-frame sections.
The 1000mm option is generally suited to:
The 2100mm option is generally suited to:
The profile may be cut shorter but cannot be extended without creating a joint.
A typical single-leaf door may require:
| Frame Section | Typical Supplied Length |
|---|---|
| Hinge-side jamb | One 2100mm length |
| Closing-side jamb | One 2100mm length |
| Frame head | One 1000mm length |
This is a general purchasing guide only.
Measure the actual door frame before ordering, particularly where the door is taller or wider than a standard internal doorset.
The soft silicone gasket should make continuous contact with the closed door.
Correct adjustment is achieved through accurate carrier positioning rather than through a mechanical actuator.
The gasket should:
The carrier position should be altered where the compression is excessive or insufficient.
The NOR755 is acoustically tested in accordance with BS EN ISO 10140-2.
The seal must not be assigned a universal standalone decibel value.
Final performance depends on:
The current official NOR755 technical listing does not state a dedicated smoke-test standard.
Do not advertise a certified smoke classification unless the appropriate current evidence is available.
Where smoke control is required, confirm:
The NOR755 does not contain intumescent material and does not independently provide fire resistance.
Where the product is installed on a fire door:
Store the NOR755:
Inspect the installed seals regularly.
Check for:
Replace damaged sections using the same specified NOR755 profile.
Norsound NOR755 Acoustic Perimeter Seal is surface mounted to the door stop around the head and jambs of a suitable acoustic doorset.
The aluminium carrier is secured using screws, after which the decorative cover strip is fitted over the fixings.
The silicone gasket must be positioned to make light and continuous contact with the door when it closes.
Inspect the door and frame.
Confirm that:
Correct substantial door-alignment or frame defects before installation.
The NOR755 is normally fitted to the surface of the door stop.
The grey silicone bubble should project towards the face of the door leaf.
Close the door and establish the carrier position at which the gasket will make light, continuous contact.
The gasket must not be:
Measure the door-to-stop gap at several points around:
A gap tolerance of approximately 3mm to 4mm is commonly recommended for the NOR755 arrangement.
Check that the gap is reasonably consistent.
Do not rely on the soft gasket to compensate for large variations caused by a warped door or misaligned hinges.
Hold a short section of NOR755 against the proposed stop position.
Close the door slowly.
Check that the silicone bubble:
Mark the successful position on the stop.
Measure the first vertical jamb from the frame head to the required lower finishing point.
Transfer the measurement to a 2100mm NOR755 profile.
Account for the selected head-to-jamb joint arrangement.
Do not assume that both jambs are identical in length.
Remove or unclip the decorative cover strip from the aluminium carrier before cutting and fixing.
Set it aside carefully.
Protect the visible satin-silver surface from:
Mark the required finished length on:
Both components should finish at the same length.
Check the measurement before cutting.
Where the gasket can be withdrawn from the carrier, move it clear of the aluminium cutting line.
Where it cannot be removed easily, protect it carefully and cut the aluminium without damaging the silicone.
Do not:
Support the aluminium carrier and cover strip securely.
Cut both components squarely using a fine-tooth saw suitable for aluminium.
After cutting:
Return the silicone gasket to its natural position where it was withdrawn.
Trim it cleanly to the required finished length.
Do not stretch the gasket while cutting, as it may retract and finish too short.
The finished gasket should remain:
Hold the prepared aluminium carrier against the marked jamb position.
Use a spirit level or straight edge to keep it vertical.
Confirm that:
Use the carrier’s fixing holes or the current manufacturer fixing arrangement to mark the screw positions.
Do not invent additional screw positions without confirming that they are suitable.
Check that the screws will not damage:
Remove the carrier and drill suitable pilot holes.
Choose the pilot-hole diameter according to:
Remove all drilling dust before fitting the carrier.
Return the NOR755 carrier to its marked position.
Secure it using the appropriate screws.
Tighten the fixings evenly.
Do not overtighten, as this can:
Close the door carefully before fitting the cover strip.
Check the silicone gasket along the complete jamb.
It should:
Reposition the carrier where the compression is unsuitable.
Repeat the measuring, cutting, positioning and fixing process on the opposite jamb.
Maintain:
Check that the seal does not interfere with hinges, strike plates or other ironmongery.
Measure the clear distance across the frame head between the installed jamb carriers.
Cut the head carrier, cover strip and silicone gasket to suit.
The head section should meet the jamb sections closely without:
Position the head carrier on the marked stop line.
Ensure it is level and aligned with both jamb sections.
Mark and drill the pilot holes, then secure the carrier using suitable screws.
Check the gasket compression by closing the door carefully.
Inspect both head-to-jamb junctions.
The joints should:
Re-cut inaccurate profiles rather than forcing them together.
Once the carrier positions and gasket compression have been confirmed, fit the decorative cover strips.
Press or clip each strip into its carrier in accordance with the profile design.
Check that:
Open and close the door several times.
Confirm that:
The NOR755 treats the head and jambs only.
Where acoustic sealing is required, confirm that the bottom of the door is treated using an appropriate:
The lower ends of the NOR755 should meet the threshold-sealing zone without leaving substantial corner gaps.
Inspect the NOR755 regularly as part of the door-maintenance programme.
Check for:
Clean the silicone gasket and aluminium cover using a soft cloth and a mild cleaning product compatible with aluminium and silicone.
Avoid:
Correct carrier positioning, secure fixing, continuous joints and suitable gasket compression are essential to the performance of the NOR755.
The product does not independently create an acoustically rated, smoke-control or fire-resisting door.
Final performance depends on:
For certified or performance-rated doorsets, install the NOR755 only in accordance with the applicable test evidence, assessment and door-manufacturer instructions.
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