OFV300 – Rytons Abutment Ventilator (297mm L)

General Details

OFV300 – Rytons Abutment Ventilator (297mm L)

  • Flat roof abutment ventilator.
  • Fixed to a timber upstand at the abutment to introduce air into the roof void.
  • Front fins prevent roof felt blocking the ventilation slots.
  • Unseen when the roof is completed.
  • 4mm ventilation slots promote unrestricted air flow and prevent the entry of birds and large insects.


  • 297mm L x 59mm W x 45mm H (see image gallery above).
  • CAD drawing available by email.

Free Area:

  • 7,500mm² per length (25,252mm² per metre).
  • Equivalent to a continuous 25mm venting gap.


  • White.


  • Polypropylene.


  • Create a void by securing a softwood timber upstand to the roof timbers at the abutment (maintaining a gap of at least 25mm with the wall). Fix to the top of the upstand through the pre-formed slots across the top of the ventilator. A timber fillet may be placed on top of the ventilator before being dressed with lead.

Handling Information:

  • Box quantity: 30 lengths.
  • Box size: 35cm W x 26cm H x 23cm D.
  • Box weight: 1.2kg.

Reference Material:

  • British Standard BS 5250.
  • The Building Regulations, Approved Document C.
  • The Building (Scotland) Regulations, Mandatory Standard 3.15.
  • The Building Regulations (Northern Ireland), Technical Booklet C.
  • NHBC Standards, 7.1 Flat Roofs.

NBS Plus Specification: