Alpha Air Ventilation Supplies
MM

INCH
View all 450mm Dampers →

Intumescent Fire Block – Square – 450mm x 450mm

Fire damper for preventing flame and smoke spread through ductwork. Intumescent Fire Block – Square automatically closes when triggered by heat or fire detection. Essential for building fire safety compliance. Tested and certified to relevant fire safety standards.

£147.23

20% VAT added at checkout

In Stock – Available for next day delivery

Order before 3pm today for delivery by Monday 14th September

Select Size

Description

The Intumescent Fire Block — Square, 450mm × 450mm, is a passive fire protection component for ventilation systems, sized to suit 450mm × 450mm square openings and ducts.

Intumescent material stays inert at normal temperatures and expands rapidly when exposed to the heat of a fire, closing off the airway to resist the passage of fire through the ventilation opening. Fire blocks are used where ductwork or ventilation openings pass through fire-rated walls and floors, helping to maintain the building’s compartmentation without the moving parts of a mechanical fire damper. Installation should always follow the project’s fire strategy and the fitting instructions supplied.

Key features

  • 450mm × 450mm square format
  • Intumescent material expands under fire conditions to seal the opening
  • Passive protection — no moving parts, actuators or fusible links
  • For ventilation openings and ducts passing through fire-rated construction
  • Available in square sizes from 150mm to 500mm

This item is normally held in stock — order by 3pm for next-working-day dispatch, and delivery is free to UK mainland addresses on orders over £400 ex VAT.

Frequently Asked Questions

How does an intumescent fire block work?

The intumescent material stays inert at normal temperatures and allows air to pass through the opening. When exposed to the heat of a fire it expands rapidly, closing off the airway and resisting the passage of fire through the ventilation opening. This maintains the building’s fire compartmentation without any moving parts, springs or fusible links.

When would I use a fire block instead of a mechanical fire damper?

Fire blocks provide passive protection where ductwork or ventilation openings pass through fire-rated walls and floors, without the maintenance and testing regime of moving-blade dampers. Whether a fire block or a mechanical fire damper is appropriate depends on your project’s fire strategy — always confirm the specified product with the fire engineer or building control before ordering.

What sizes are available?

The square intumescent fire blocks are stocked in eight sizes from 150mm x 150mm up to 500mm x 500mm, in 50mm steps, sized to suit the matching square openings and ducts. Choose the size that matches your duct or ventilation opening; if you need help matching a block to an opening, contact us before ordering.

How are they installed?

Installation should always follow the project’s fire strategy and the fitting instructions supplied with the block, since correct fitting is essential to fire performance. As a passive component there is no wiring or actuation to connect — the block sits within the opening it protects. Keep a record of the installation for the building’s fire safety documentation.

Delivery Information

In Stock

Next Day Delivery — order before 3pm Monday to Friday for dispatch the same day.

Delivery Options

ServiceEstimated DeliveryCost
Standard Delivery (UK mainland)Next working day from dispatch£15.95 +VAT (£7.95 for small items)
Free DeliveryNext working day from dispatchFree on orders over £400 ex VAT
Click & CollectCollect from our Leicester branchFree
Scottish Highlands & Islands2-3 working days from dispatch£36.95 +VAT

Delivery Area

We deliver to all UK mainland addresses. Scottish Highlands and Islands deliveries may take a little longer. We are not currently delivering to Northern Ireland — Click & Collect remains available.

Questions about delivery? Call us on 0116 246 0031 or email sales@alphaair.co.uk

Returns Policy

Six-Week Returns — No Restocking Fees

We want you to buy with confidence. You can return any standard stocked item within six weeks (42 days) of delivery for a full refund — 100% of the item price, no restocking or handling fees. Trade and business customers get exactly the same rights as retail customers. See our Returns Policy for full details.

Return Conditions

  • Items must be unused and in original packaging
  • Custom-made, bespoke or powder-coated items are made to your specification and cannot be returned unless faulty
  • Items must be returned with proof of purchase
  • Return shipping costs are the responsibility of the customer unless the item is faulty

How to Return

  1. Contact our customer service team to arrange a return
  2. Pack the item securely in its original packaging
  3. Include your order number and reason for return
  4. Ship the item to our returns address

Faulty Items

If you receive a faulty or damaged item, please let us know as soon as possible — ideally within 48 hours of delivery, so we can claim against the courier on your behalf. We will arrange a free collection and send a replacement or issue a full refund. This does not affect your statutory rights.

Questions? Contact us at sales@alphaair.co.uk

Calculating delivery... order within --h --m --s (3pm cutoff, stock items) Need it sooner? Contact us