Manthorpe Building Products

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Felt Lap Vent

The Manthorpe Felt Lap Vent is a refurbishment product designed to increase the amount of ventilation into existing roof spaces. Usually fitted retrospectively to properties with additional loft insulation recently installed, however the Felt Lap Vent will help to combat the problem of condensation build up in any roof space with a lapped felt/membrane construction.

The specifier should ensure that the opening of felt laps on the property will not adversely increase the wind uplift load on the tiles/slates or the driving rain resistance of the roof, for more information see BS 5534:2003, 5.8.1 &


Product Benefits

  • Can be fitted at joist centres ranging from 400mm to 600mm
  • 3,000mm2/m airflow
  • Easy to fit, the tapered lead in helps to slot the product between the felt laps
  • The 3 felt clips help secure the product in place even if the edge of the felt is degraded

G630 Installation Video

The clip below illustrates the fitting detail and operational function of the G630 Felt Lap Vent.

Product Specifications

Product Code Description Free Airflow Size Material Colour Box Qty
G630 Felt Lap Vent 3,000mm² 275mm x 193mm Polypropylene White 50