Fire Stop Blocks

Fire and smoke stop blocks for apertures in buildings, especially the flutes of trapezoidal formwork.


AIM Fire Stop Blocks are made from high density Rockwool stone wool. Incorporated into the building during construction, they are used to seal apertures and are permanently held in place by compression. They can also be used within metal cladding as a fire break and to protect the top flange of steel beams. AIM Fire Stop Blocks are predominantly supplied as trapezoidal sections. Square cut, rectangular or round sections are also available.


Used to seal imperfections of fit within the construction and maintain fire compartment lines.

Predominantly supplied as trapezoidal sections, square cut, rectangular, round or sinusoidal sections also available.


  • Composite Flooring Profiles
  • Dovetail Composite Flooring Profiles
  • Metal Decking, Roofing and Cladding

Fire Stop Blocks are designed for use in trapezoidal formwork (metal decking) typically at the head of a wall (as shown in the illustrations)

Fire Stop Blocks may be used elsewhere in a building and may require approval, for example filling holes within a building.

AIM Fire Stop Blocks can be used at the head of a partition wall if the head track is fastened to the metal deck.


  • Simple to install – no tools required.
  • 1 and 2 hour fire rating.
  • Ablative / pre-painted option available.
  • Manufactured to any profile or customers dimensions.
  • Up to 1200mm long


  • Maintains fire compartment lines
  • A barrier to the movement of smoke.
  • Contributes to acoustic performance of the wall or partition
  • Many profiles CNC Cut for ultimate accuracy especially for profiles with rounded shoulders


• Minimum block length: 75mm
• Maximum length = 1200mm
• Minimum block height = 10mm
• Max block height = 100mm
• Widths to suit the profile
• Compression fit so no mastics or sealants required
• Tested to EN 1366-4: 2010
• Ozone depletion potential of zero, no CFCs or HCFCs used in manufacture
• Global warming potential = zero

The AIM Fire Stop Blocks can be manufactured to suit any metal decking profile. In many instances we already hold detailed data regarding the specification of leading brands of metal deck. If this information is not available we can also manufacture blocks to the customers specification for this option we will need the following dimensions:

We will also need to know if your customer requires a special length of block (i.e. to match the with of a wall or partition) or if a specific fire rating is required.

Majors and minors:
The minor block sits above the major block to fill the dovetailed web stiffener. (Sometimes this minor void iscompletely filled with an intumescent mastic)

Large and small flute:
Viewing the profiled decking from the panels end; the larger of the trapezoids is the large flute, (the smaller being small flute). Either large or small flute may be required depending upon which way up the decking is laid


AIM Fire Stop Blocks are often used in conjunction with:

• AIM Fire Stop Strips which are used as a deflection head detail with masonry walls.
• AIM Acoustic Trough Infills where perforated metal sheeting is used as to form a roof structure and the flutes require an acoustic filler.

Advance Manufacturing Capability

AIM’s investment in CNC Wire Saw technology enables the manufacture of Fire Stop Blocks to suit almost any metal deck profile irrespective of the complexity of the design.

The Fire Stop Blocks are manufactured using the CAD details from the metal deck manufacturer. The cutting process then faithfully follows the exact outline of the metal deck profile, including any stiffners or other design features.

This capability can be applied to a variety of insulation materials but typically, for Fire Stop Blocks this is primarily Rockwool Stone wool or Rockwool Ablative Coated batts. AIM’s CNC Wire Saw Cutting technology can also be adapted to the manufacture of fire stop blocks to sinusoidal profiles or other, bespoke metal sheet patterns. The resulting fire barrier may require the approval of a competent person where a specific fire performance is required.

Range of Ablative coated batt fire stop blocks

AIM Ablative Fire Stop Blocks are ideal for applications where aesthetics or fibre migration are a concern. Used to close the flutes above internal fire rated walls and partitions they maintain the fire compartment line and provide a high acoustic performance (up to 34dB / single layer) when sealed

around their perimeter (on both faces) with Rockwool Acoustic & Intumescent Sealant. Ablative Fire Stop Blocks are cut using CNC technology ensuring their accuracy making the installation faster and tidier than conventional straight sided trapezoidal sections.


AIM Linear Fire Stop Blocks are used in composite panel constructions where a compartment line needs to be extended through the panel.

AIM’s CNC Wire Saw enables the production of a linear fire barrier that is effectively the combination of several Fire Stop Blocks and a Fire Stop Strip into a single item.


Where a fire wall is built to the underside of a perforated metal deck, AIM Fire Stop Blocks should be installed above and below deck at the line of the wall to ensure that smoke or fire is prevented from passing through the perforations in the metal work.

AIM Fire Stop Strip can also be used to remove any imperfections in the head of the wall to the underside of the metal deck.

AIM Acoustic Trough Infills are then used across the metal deck, to assist with the reduction of noise reverberation from within the building.

The performance of the AIM Fire Stop Block is dependent on the metal deck remaining stable in a fire situation and should be assessed by a competent person.



The product achieves Euroclass A1.

Fire Rating (Integrity / Insulation)

Masonry to Masonry:
75mm = 120/60 & 100mm = 120/120

Masonry to MasonryYes120/60120/120

They are installed under compression (minimum 5% compression required). Fire Stop Blocks may be used elsewhere in a building but will require approval. Can be used at the head of a partition if the head track is fastened to tghe metal deck but should be approved by a Fire Engineer or Building Control.


AIM Fire Stop Blocks provide at least 14dB RW sound reduction. The acoustic performance of the floor and wall systems must also be considered when assessing the room-to-room sound reduction figure.

75mm long block = 14dB RW
100mm long block = 18dB RW
140mm long block = 23dB RW

Air leakage

AIM ablative coated fire stop blocks provide a robust solution to air leakage requirements. These are available to suit most major cladding and decking profiles

Mastic must be used to seal the perimeters of the Fire Stop Block


WF 432745

Z11012 – Acoustic Performance – Testing on mineral fibre insulation. Dated 17th August 2011. EN ISO 10140-2.


More drawings available in the Technical Guide which can be downloaded above.


AIM Fire Stop Blocks are push fitted into place; they must fit tightly and completely. Dovetail fire stops are supplied as rectangular blocks, which are pinch fitted into the profile, then pushed into place.


• PPE abrasion resistant gloves
• PPE impact resistant goggles
• RPE dust mask


Products are supplied in cartons and on wooden pallets with edge protection and a shower proof hood. Products should be stored away from the elements until ready for installation.


This product does not contain moving parts and, if undisturbed in the cavity, requires no routine inspections or maintenance.

It is recommended that the integrity of the barrier is rechecked if further works are carried out, which may involve disturbing the product.


AIM fire barriers are chemically inert, will not sustain vermin and do not encourage the growth of rot, fungi, moulds or bacteria. They are compatible with all normal building materials. They do not degrade under the usual conditions found in buildings and will perform effectively for the life of the building.


Insulation products supplied by AIM are considered to be inert articles and as such are exempt from requirements to provide a Safety Data Sheet.

A Product Safety and Handling Information Sheet is available upon request.


Global warming potential = zero

For product recycling please contact: Rockwool
T: 01656 868400 e: [email protected]


To order this product the following information will be required: • The manufacturer and reference for the metal deck. Typically a metal deck reference will be along the lines of: Wards MD60, Corus CF70, SMD TR60, Rigidal 20/100/1000 and similar

• If this information is not available we can also manufacture blocks to your customers specifications; for this option we will need the following dimensions:

All AIM fire barriers are made to order. Products are typically supplied in seven to ten working days but lead times may vary depending on existing factory commitments.

There is no minimum order quantity or value although small orders may attract transport surcharges


Technical Support is available from our experienced sales team on 01293 582 400 or [email protected]

Our Partners & Affiliates

AIM are partners with NBS. Our products can be found on NBS Source and have been authored to NBS specification standards and have both CAWS and Uniclass 2015 classifications.

AIM are members of ASFP.

AIM working in partnership with Rockwool.