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, the Felt Lap Vent helps 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 &

Features and benefits:

  • Can be fitted at joist centres ranging from 400 to 600 mm.
  • 3000 mm²/m airflow.
  • Easy to fit, the tapered lead in helps to slot the product between the felt laps.
  • The three felt clips help secure the product in place even if the edge of the felt is degraded.

Standard product features


275 x 193 mm.

Product specification

An important note about specifying



Manthorpe Building Products Ltd


+44 (0)1773 303000

Product reference

G630 Felt Lap Vent

Manufacturer details

Manthorpe House,
Brittain Drive,
Codnor Gate Business Park,
Derbyshire, DE5 3ND
Tel +44 (0)1773 303000
Fax +44 (0)1773 303300
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