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Airbricks and External Cowls

An effective, robust and durable airbrick ventilator presenting a equivalent area of 6170mm² (free area of 6500mm²) .

Ideal for underfloor or room ventilation applications when used with the Timloc telescopic underfloor vent or cavity sleeve.

The front grille is designed to provide a free unobstructed airflow and yet prevent the ingress of wind driven rain.

Integral clip togther facility alows multiple airbricks to be stacked to form 9" x 6" and 9" x 9" sizes.

Available in buff, grey, terracotta, white, brown blue/black and black.

Brown and Terracotta external airbrick cowls available in 9 x 3", 9 x 6", 9 x 9" and 7 x 7".

For more information call 01405 765567 Free next day delivery *

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Features & Benefits

  • Unique stepped front grille greatly reduces the entry of wind driven rain
  • Available in a range of colours to blend in with various brick types
  • Very tough and robust
  • Durable and totally resistant to decay


  • Used in conjunction with the Timloc Telescopic Underfloor Ventilator for providing ventilation below a suspended ground floor
  • Used in conjunction with Timloc Cavity Sleeves for ventilation through external walls to a building interior

Technical Information

  • Equivalent area 6170mm² per unit (6500mm² free area)
  • 6.5mm wide front grille openings comply with BS 5440 Pt 2 and British Gas requirements
  • Integral clip together facility allows multiple airbricks to be stacked to form 9” x  6” and 9” x  9” sizes
  • 9″ x 6″ cowl (1230) version available to replace double air brick – provides an equivalent area of 11,000mm²

How to Order

  • Airbrick quantity will be relative to the number of telescopic underfloor ventilators or cavity sleeves required
  • State the colour required.

Installation Advice

Underfloor ventilation

If a building uses a suspended ground floor, it is important to provide ventilation into the underfloor void. This prevents condensation, removes stagnant air and is particularly important in areas where radon or methane gas may pose a problem. The provision of ventilation is important regardless of whether the suspended floor is of beam and block or traditional joist and floor board construction.

The ideal method for providing ventilation into the underfloor void is to use the Timloc Airbrick and the Timloc Telescopic Underfloor Ventilator.

  • The airbrick and underfloor ventilator must always be used together
  • The airbrick is a push fit into the upper front opening of the ventilator
  • The airbrick and ventilator should ideally be spaced along the wall at not more than 2m centres with the first and last ventilator being positioned within approximately 450mm of the wall corner. This is to ensure a good flow of air and to eliminate areas of calm air where stagnant air pockets could form
  • If the building is a simple rectangular shape on plan, it is acceptable to install airbricks and ventilators along the two longest of the building.
  • If the building is 'L' shaped or of more complex design, the airbricks and ventilators should be installed around the full perimeter of the building
  • It is important to provide corresponding ventilation openings in any internal dividing walls so as to allow air to circulate throughout the underfloor void
  • The airbricks should be built into the external wall above the finished ground level so as to prevent rain and snow water from entering the ventilator. They would usually be positioned at a similar level to the ground level DPC
  • The lower section of the ventilator should be extended down to the level of the underfloor void by means of its telescopic action. This can accommodate a step up of five vertical brick courses. The inner leaf blockwork must be cut to allow positioning of the lower section of the ventilator. If the design of the building is such that the standard ventilator is not long enough, then a vertical extension sleeve is available which will extend the ventilator to a height of nine vertical brick courses
  • The standard ventilator suits a wall with a 100mm thick outer leaf, 50mm cavity and 100mm thick inner leaf. If the cavity is slightly wider or the inner leaf slightly thicker than these dimensions, then the standard ventilator will usually still be acceptable as long as the cut-out in the inner blockwork is kept clear. For thicker outerleafs, a horizontal front extension is available and a horizontal rear extension for use with particularly wide cavities or thick inner blockwork

Telescopic gas vent outlets


The combined units will alow ventilation outlets to either a sub floor void, or, via a range of adaptors to a venting layer and allow the provision of a minimum of one complte volume change per 24 hours, as required by the NHBC. The Timloc vent units will achieve an airflow rate of 4.85L/sec (17m³/hr) or equal to an equivalent area of 6000mm². NB. All airflow testing has been independently tested by the BRE to BS EN 13141-1.

Through the wall ventilation

Through the wall ventilators provide passive ventilation through external walls into habitable rooms. It is important to differentiate between a ventilator which is required to provide general background ventilation and one which provides air into a room which contains a heat producing appliance such as a central heating boiler or gas fire.

  • If only general background ventilation is required, then product selection is less critical. A habitable room requires a free airflow of 8000mm² in order to comply with Building Regulations. This can be provided using two Timloc airbricks complete with cavity sleeves and internal louvred or hit and miss grilled. Alternatively, any one of the anti draught ventilator products can be used
  • If the room contains a heat producing appliance, the provision of constant and reliable ventilation is vitally important. The anti draught ventilator products are re strongly recommended for this application, as they comply fully with legislation governing gas and hea appliances. The size and number of anti draught ventilator products required will be dictated by the requirements of the particular heating appliance, it is strongly recommended that advice is sought from the manufacturer

General recommendations for the specification and use of through the wall ventilators are detailed below:

  • Always check that the appropriate size and number of through the wall ventilators are used to suit the application
  • Never fit just an airbrick. A cavity sleeve must always be fitted to the back of the airbrick to ensure that the air is transmitted effectively through the wall and into the room
  • Hit and miss grilles may only be used for general background ventilation, they must never be used to ventilate any kind of gas or heating appliance
  • Ventilators used to provide air for gas or heating appliances must be permanently open, there must be no facility to block or close the ventilator. Also, the must not contain any kind of fine mesh or insect screen
  • Through the wall ventilators should always be fitted well above the external ground level, so as to ensure that rain and snow water cannot enter the ventilator
  • It is recommended that a section of horizontal cavity tray is installed directly above the through the wall ventilator, so as to prevent water from tracking across the cavity sleeve from the outer leaf to the inside of the building
  • In order to help reduce the effect of draughts, it is worth considering positioning the through the wall ventilator close to any heating appliance, rather than at the opposite side of the room. Positioning the ventilator at a high level instead of close to the floor, will also be of assistance

Regulations and Standards

  • Satisfies all NHBC Standards
  • Manufactured to BS EN ISO 9001:2008
  • Manufactured to BS EN ISO 14001:2004
  • Complies with all relevant Building Regulations
  • Meets all relevant British Standards
  • 'Equivalent Area’ tested by BRE to BS EN 13141-1:2004
  • Equivalent area marking fron frotn face of airbrick to comply with BS EN 13141-1:2004

Material and Colour Choice

  • Manufactured by injection moulding in UV stabilised polypropylene
  • 1201AB airbricks are available in buff, terracotta, grey, brown, white, blue/black and black
  • Double airbrick replacement cowls are available in buff, brown and terracotta
  • External cowls are available in brown and terracotta
  • nbs plus
  • riba

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