ISL Therm-A-Glaze 30 Glazing Seal – 10 × 2mm × 2100mm is a flexible, self-adhesive intumescent strip developed for approved glazed apertures in 30-minute fire-resisting timber doorsets.
The dry glazing material is applied to the glazing beads before the fire-resistant glass is installed. During normal conditions, it forms a slim sealing layer within the glazing pocket. When exposed to elevated temperatures during a fire, the intumescent material expands to fill gaps and form a dense carbon barrier around the glazed aperture.
Each strip is supplied in one fixed configuration:
Therm-A-Glaze 30 is intended for use as one component within a suitable 30-minute fire-resistant glazing system.
Its function is to help protect the junction between:
The seal expands under fire conditions to help restrict flames and hot gases from passing around the edges of the glass.
The product does not independently provide a 30-minute fire rating. Performance belongs to the complete tested or assessed doorset, including the door leaf, glass, glazing beads, setting blocks, bead fixings and installation detail.
Therm-A-Glaze 30 combines the fire-sealing properties of an intumescent material with the flexibility of a thin glazing strip.
The flexible construction makes it suitable for accurate fitting along glazing beads and around rectangular glazed apertures.
The profile can be:
The strip should not be stretched during installation, as it may retract and create gaps between adjoining sections.
The integral self-adhesive backing allows the strip to be applied directly to a clean and dry glazing bead.
This helps retain the material while:
The adhesive is an installation aid only. It does not structurally support the glass or replace the mechanical bead fixings and setting blocks required by the complete glazing system.
Therm-A-Glaze 30 is intended for glazing applications where generous intumescent expansion is required.
When activated, the material expands into available spaces and develops a dense intumescent carbon layer.
This can help:
The required expansion space, bead dimensions and glass clearances must follow the applicable fire-test or assessment evidence.
Certifire certificate CF284 covers Therm-A-Glaze 30 in specified timber-based doorsets for 30 minutes’ fire integrity.
The certified basic arrangement includes:
The doorset must already be fire tested or Certifire approved for the inclusion of a glazed aperture of the proposed dimensions.
The certified Therm-A-Glaze 30 arrangement provides:
Integrity relates to the ability of the complete assembly to restrict flames and hot gases.
Do not describe this glazing seal as independently providing thermal insulation. Any insulation performance must be supported by evidence for the selected glass and complete glazed construction.
The current certificate includes specified fire-resistant glass products and maximum pane dimensions for the Therm-A-Glaze 30 arrangement.
Compatibility depends on:
Do not substitute another glass solely because it has the same nominal thickness or advertised fire rating.
Therm-A-Glaze 30 is supplied in a Dark Grey finish.
The strip is normally largely concealed between the glass and glazing bead once installed. A narrow sightline may remain visible depending on the bead profile and glazing arrangement.
The material should not be painted or coated unless the manufacturer and doorset evidence expressly permit the proposed finish.
Each product is supplied as one 2100mm strip.
The number of lengths required depends on:
Calculate the full perimeter of each aperture before ordering.
Before ordering or installing, confirm:
Do not create or alter a glazed aperture in a certified fire door unless the modification is supported by the door manufacturer’s evidence or a suitable fire assessment.
| Product Name | ISL Therm-A-Glaze 30 Glazing Seal – 10 × 2mm × 2100mm |
| Manufacturer | Intumescent Seals, a division of Dixon International Group Ltd |
| Manufacturer Product Reference | SYSGZ30 |
| Stocked Product Code | THE30 |
| Product Type | Flexible self-adhesive intumescent fire-glazing strip |
| Application | Approved glazed apertures in 30-minute timber-based fire doorsets |
| Profile Size | 10 × 2mm |
| Length | 2100mm |
| Colour | Dark Grey |
| Fixing | Integral self-adhesive backing |
| Cutting Method | Sharp scissors or a suitable knife |
| Certified Fire Integrity | 30 minutes within the specified certified glazing system |
| Certified Insulation | 0 minutes for the listed Therm-A-Glaze 30 arrangement |
| Test Standard | BS 476: Part 22: 1987 under the current Certifire approval |
| Certification | Certifire TS25 Certificate CF284 |
| Certificate Reissue Date | 21 July 2025 |
| Certificate Valid Until | 10 June 2030 |
| Certified Door Type | Timber-based fire-resisting doorsets |
| Nominal Certified Door Thickness | 44mm within the basic CF284 arrangement |
| Standalone Fire Rating? | No — performance belongs to the complete tested or assessed glazing system |
| Standalone Smoke Rating? | No separate cold-smoke classification should be assumed |
| Standalone Acoustic Rating? | No |
| Profile Size | Length | Colour | Product Code |
|---|---|---|---|
| 10 × 2mm | 2100mm | Dark Grey | THE30 |
| Size Options | Length Options | Colour Options | Total Variations |
|---|---|---|---|
| 10 × 2mm | 2100mm | Dark Grey | 1 |
Certifire CF284 identifies the following basic Therm-A-Glaze 30 construction:
This is the certificate’s basic approved arrangement. Project-specific doorset evidence may impose additional or different limitations and must always be checked.
The current certificate lists specified glass products for the Therm-A-Glaze 30 arrangement, including:
Maximum permitted dimensions vary by glass type. Do not use this list as authority to substitute glass products without checking the current certificate and doorset evidence.
Store Therm-A-Glaze 30:
Do not install material that is:
Therm-A-Glaze 30 must be installed as part of a tested, certified or assessed fire-resistant glazing system.
The fire door, glazed-aperture dimensions, glass, glazing beads, setting blocks, fixings and intumescent material must all match the applicable supporting evidence.
Confirm:
Do not machine or alter a certified fire door unless the proposed glazing arrangement is expressly permitted.
Check that the prepared opening is:
Stop work where the exposed door construction does not match the expected fire-door evidence.
For the basic CF284 Therm-A-Glaze 30 arrangement, the hardwood glazing beads are:
Prepare the beads to the exact dimensions required by the applicable certificate or doorset assessment.
The surfaces receiving the self-adhesive strip must be:
Remove all machining dust before applying the glazing seal.
Measure the length of the first glazing bead.
Transfer the measurement to the Therm-A-Glaze 30 strip without stretching it.
Allow the ends to meet adjoining seal sections closely at the bead corners.
Cut the material cleanly using sharp scissors or a suitable knife.
Do not:
Remove a short section of the adhesive release liner.
Align the strip on the glazing bead and press it firmly into position.
Continue removing the liner progressively while working along the bead.
Ensure that:
Prepare the bead corners using the joint arrangement required by the doorset evidence.
Check that the adjoining intumescent strips:
Fit the first set of glazing beads into the aperture.
For the basic CF284 arrangement, secure the beads using:
Use the exact fixing positions, angles and edge distances required by the project-specific evidence.
Position the approved non-combustible or hardwood setting blocks.
The setting blocks support the glass and maintain the required edge clearances.
Do not rely on the Therm-A-Glaze 30 strip to support the weight of the glass.
Install the approved glass using suitable handling equipment.
Confirm that:
Prepare and install the opposing bead assembly using the same glazing-seal arrangement.
Secure the beads using the specified mechanical fixings.
As the fixings are tightened, check that:
Inspect the glazing system on both faces.
Confirm that:
Inspect the complete glazed aperture as part of the fire-door maintenance programme.
Check for:
Therm-A-Glaze 30 does not independently provide 30 minutes’ fire resistance.
The certified performance depends on the complete glazing system, including:
Install the product only in accordance with current certification, fire-test evidence, assessment documentation and the instructions applicable to the complete doorset.
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