Manthorpe Felt Lap Ventilator G630
The Manthorpe G630 Felt Lap Vent is a refurbishment ventilation product that is fitted retrospectively to assist in overcoming the problems with condensation, often found when additional loft insulation has been recently installed
The Manthorpe G630 Felt Lap Vent is designed to be fitted retrospectively to existing lofts to increase the amount of ventilation into existing roof spaces.
The Manthorpe G630 is usually fitted 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 product can be easily installed by one person in joist openings from 400mm to 600mm wide to provide 3,000mm² of airflow per unit.
The product will not meet the requirement for roof ventilation solely on it’s own, it will only provide airflow through the felt laps. Other measures may need to be in place to ensure that the adequate amount of ventilation is provided for the roof space.
The specifier should also 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 & 6.2.1.1.

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