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Easy vent v manthorpe felt lap vent?

Which is better for ventilation in the loft - easy vent or Manthorpe felt lap vent? Cheers

2 Answers from MyBuilder Roofers

That is going to depend your loft make up and insulation types your best bet is to check the manufacturers websites for the loft types that are closest to yours then have a quick chat with your Architect and builder before final purchase, this works 99% of the time.

Good luck with your Project


Answered 25th Feb 2017

I as a previous installer of these would definitely recommend Manthorpe vents as per ease of use and various areas they are used in.
I have copied and pasted their website update page here but you can visit the website and get a good all round evaluation of their system and how it works.
Please note the areas of concern over wind lift when installing.

* 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 integral felt clips help secure the product in place even if the edge of the felt is degraded
Manufacturers Part No: G630
Manthorpe G630 Roof Felt Lap Ventilator

The Manthorpe G630 Felt Lap Vent is a refurbishment product designed to increase the amount of ventilation into existing roof spaces.
Each unit will provide 3,000m square metres; of free airflow into the batten void
For further information on the recommended ventilation requirements for roof spaces refer to BS 5250 Code of Practice for Control of Condensation in Buildings
Orientate the G630 so that flat face is facing upwards and the curved face with the felt clips is facing down
Push the tapered front edge of the vent into the lap of the felt, once the front edge is in; pivot the vent up flat against the felt forcing the lap apart
Push the vent down into the felt lap, ensuring the flat top is in line with the underside of the battens
When the vent is almost in position, the felt clips will slide over the lower lap of the felt
Ensure that all 3 clips are properly located before proceeding
Once correctly installed all that will be visible of the vent is the top edge with the stated airflow of 3,000m square metres; and the 3 felt clips
Working across the roof space, slot the vents into the appropriate felt laps between joist openings to give the required amount of ventilation
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 or membrane construction

Note: 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 &

Hope this Helps,

Pete West Wilts Roofing.


Answered 23rd Jun 2018

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