top of page
Timloc Telescopic Underfloor Vent 5-7 Courses (1201XL)

Adjustable ventilator to provide ventilation beneath suspended ground floors between 5-7 brick courses. With incorporated grille to prevent vermin entry.

The vertical height of the ventilator unit adjusts to suit between 5 and 7 brick courses (375mm-525mm) with a minimum cavity width of 50mm.

We have an extensive range of easy-to-fit horizontal and vertical extension accessories, that do not restrict airflow, to adapt the unit for various applications.


  • To provide ventilation below suspended ground floors.

Timloc Telescopic Underfloor Vent 5-7 Courses (1201XL)

Sales Tax Included
  • • Always use in conjunction with a Timloc airbrick
    • The airbrick and upper front opening of the telescopic underfloor ventilator must be positioned above the finished external ground level - usually at the same level as the ground level DPC
    • The lower rear opening of the product must project down to the level of the underfloor void and must not be obstructed by the floor construction. A vertical extension sleeve is available to fit with this product if the standard 7 course step is not adequate
    • Building Regulations require a free airflow below suspended ground floors of at least 1500mm2 per metre run of wall. This can be achieved by spacing the ventilators at 4m centres, however, such a wide spacing is not recommended as stagnant air pockets could form in the underfloor void. Timloc recommend a spacing of not more than 2m centres to comply with NHBC standards.
    • The NHBC recommend that underfloor ventilators are spaced at a maximum of 2m centres, with ventilators also positioned not more than 450mm from the ends of the wall
    • As a minimum requirement ventilators should be positioned down two opposite sides of the building so as to create a cross flow ventilation action. It is good practice to position ventilators around the full perimeter of the building, particularly with complex building designs
    • If the underfloor void is separated by dividing walls, openings must be provided to allow a free flow of air around the underfloor void
    • The standard ventilator will fit into a cavity wall with an external leaf of 100-102.5mm, a minimum cavity width of 50mm and across a cavity of 150mm. External and internal horizontal extension sleeves are available to accommodate thicker walls or wider cavities
    • To be installed with a DPC Cavity tray and wall weeps to collect any water ingress. We recommend Timloc’s IL4 and 2 weeps (Invisiweep or 1143)
    • When incorporating with a gas barrier system and adjusted to the required height, the joining sections should be sealed with proprietary tape.
    • It may be a requirement to protect with a lintel for direct loads N.B. The 1201XL is designed for use with a 1201AB airbrick. It can be used with a clay airbrick but this will reduce the overall airflow.

bottom of page