Dunbrik A1 Concrete Flue Liner System - 300mm square

Square Flue Liner System for Open Fires

300mm square

Suitable for:
Wood burning open fire with 300mm id chimney flue system

Straight Flue

Select chimney height*
* From finished floor level to underside of pot

Offset Flue

Select chimney height*
* From finished floor level to underside of pot

Offset Twice

Select chimney height*
* From finished floor level to underside of pot

Benefits of a Chimney

  • A chimney adds appeal to a house
  • A real fire turns a house into a home

Benefits of Dunbrik liner systems

  • Full system from the specialist manufacturer
  • Detailed flue estimates prepared
  • Systems designed for better flue flow
  • Designed for easy installation
  • Liners meet the highest industry standards
  • Expert technical advice

Key System Features

  • For domestic fires and stoves
  • Can use all domestic fuel: coal, wood, oil and gas
  • Round liners and full unrestricted bends for better flue flow
  • Tested by BSRIA to European Standard
  • Passed highest standard type A1 T600
  • Sootfire resistant to 1,000oC

Straight flue liner 230mm tall

Straight flue liner 140mm tall

Liner bend 30°

Throat Lintel 1000mm wide

Lintel spacer gather

Canopy connection block

300mm round straight pot

Topguard steel cowl 350 wide

Dunseal fireproof mortar 310ml

Void infil 20kg agg & 2kg cement

Smoke pellets – 6 per tube

Flue notice plate

Air brick 9″ x 3″ (polypropylene)

Cavity sleeve (black high impact styrene)

System details and design guidance

The Dunbrik A1 Concrete Flue Liner Systems are used in the construction of domestic chimneys suitable for all types of domestic fires. A chimney is a structure made with a minimum of 100mm thick masonry lined with purpose made flue liners. Householders can burn all domestic fuels including coal and properly seasoned wood or install any gas appliance including flame effect fires.

Flue Liners

Dunbrik concrete liners are made with tongue and socket joints. They are manufactured from kiln burnt aggregate and Portland cement and are designed to withstand repeated temperature fluctuations.

Flue liners should be joined with Dunseal fire proof mortar paste. Allow approximately 3 joints per cartridge for 200mm liners, 2 joints for 250mm & 300mm liners and 1 joint for 450mm liners. Any void between flue liners and masonry surround should be filled with Dunfil insulating infill.

Liner Standards

British Standard BS EN 1857 established performance standards for concrete flue liners for domestic chimneys.

Dunbrik liners have been tested by BSRIA and achieved the highest categories in each class as follows:

Dunbrik Type A1 – T600 N1 G D 3

Performance Data

  • T600 – Temperature nominal operating temperature 600°C
  • N1 – Gas tightness negative pressure test at 40 Pascal
  • G – Sootfire resistance heat shock tested to 1,000°C for 30 minutes
  • D – Condensate resistance for dry flue conditions
  • 3 – Corrosion resistance for all domestic fuels (scrub test for durability)


UK Building Regulations ADJ

Dunbrik A1 Concrete Flue Liners meet the minimum standards set in approved document J (ADJ) and exceed the requirements for temperature and gas tightness.

Chimney Check and Smoke Testing

The methods of checking compliance with UK building regulations are set out in ADJ appendix E available on the government website: –