SVFMIN – Rytons Flyscreened Slim Vent® Minor (Cavity Vent/Weep)

General Details

SVFMIN – Rytons Flyscreened Slim Vent Minor (Cavity Vent/Weep)

  • Perpend cavity ventilator with internal flyscreen for use in timber frame and traditional build.
  • Flyscreen located centrally for a neat appearance and to prevent accidental blockage by paint and airborne debris.
  • Unique internal water baffles and specially tapered surfaces prevent water transfer and make the vent an effective weep hole for drainage.
  • Unique internal water baffles and specially tapered surfaces prevent water transfer and make the vent an effective weep hole for drainage.
  • Clean lines maintain the aesthetic appearance of the building.
  • To protect the outlet from blockage during rendering or water penetration during flooding use Rytons DamRyt® Slim Vent Protector DAMSLIMVENT.
  • PLEASE NOTE: This item is a plastic component and therefore not suitable for use within the external walls of high-rise buildings requiring non-combustible materials, i.e. those 18m high or more complying to Regulation 7(2) and Approved Document B, and those 11m high or more complying to 2.7 of Building (Scotland) technical handbook 2019.  For compliant alternatives, which includes our tailor-made design service, see Rytons A1 Fire-rated Ventilation Range.


  • 103mm L x 66mm H x 10mm W (allows a 6mm venting gap) (see image gallery above).
  • CAD drawing available by email.

Free Area:

  • 265mm² per unit.


  • Clear: SVFMINCL.
  • Terracotta: SVFMINTC.
  • Buff/Sand: SVFMINBS.
  • White: SVFMINWH.
  • Grey: SVFMINGR.


  • High impact polystyrene.


  • Installation is fast and easy as work proceeds with the Slim Vent replacing the vertical mortar joint.  Lower ventilators should be placed below the dpc, unless cavity trays are used when they should be positioned above the tray.  Vertically stagger vents when placing them above and below horizontal fire stops.  See below for spacings.

Reference Material:

  • Install every 480mm or approximately every 2nd brick to NHBC Standards 6.2, External timber framed walls.  A drained and vented cavity should be provided to reduce the risk of rain penetrating the frame.  Where the areas are divided by horizontal cavity barriers, openings should be provided to each section equivalent to open brick perpends every 1.2m.  This equates to 650mm² free air every 1.2m.  That’s 1no SVFMIN every 480mm or approximately every 2nd brick.  Proprietary perpend ventilators should be used to provide drainage of the cavity.
  • Install every 1062mm or approximately every 5th brick to The Building (Scotland) Regulations – Domestic, 3.10.6, Masonry outer leaf.  Where the outer leaf is a masonry construction, cavities should be vented to the outside air by installing ventilators with at least 300mm² free opening area at 1.2 m maximum centres.  This equates to 1no SVFMIN every 1062mm or approximately every 5th brick.  Precipitation, i.e. rain, snow and sleet, can penetrate the outer leaf of an external wall and cavities are normally drained through weep holes.  These weep holes can also provide the necessary venting.
  • Also, refer to British Standards BS 5250.
  • Important: Not all manufacturers’ weep holes have the capability to provide the necessary venting.  Check the air space of your weep vent, check your spacing!

Handling Information:

  • Box quantity: 100 number.
  • Box size: 26cm W x 22.5cm H x 15cm D.
  • Box weight: 2.2kg.

NBS Specification: