This will vary dependant on the level of extra ventilation required and length of the roof.

To provide typical ventilation, allow for 1 lap vent every alternate rafter space at low level, on opposite sides of the roof. If maximum ventilation is required, install at high level and every rafter space along the full length of the roof.

For further installation advice visit our How to Install page.

The lap vent slots between roof felt/membrane laps.

To prevent unnecessary waste, paper fitting instructions are not included with the Lap Vents. Scan the QR code on the bag to be taken to online fitting instructions and video demonstration on how to install. You can find these instructions on the How to Install page here.

The purpose of the lap vent is to allow air and cross flow ventilation into your loft space. In a well-insulated loft this should not affect the temperature of the house.

Lap Vents can be installed with any tiled roof that has a membrane.

Installing a Lap Vent is a remedial solution to help combat condensation forming in your loft space. If condensation is still present with lap vents fitted, this can reveal the roof needs further assistance to help draw out moisture. Other products such as roof tile vents can be integrated into your roof to improve ventilation. Speak to a professional roofer for advice on roof tile vents and any other alternatives to help ventilate your roof space.