Getting the Most from Active Vent

A vent is only as good as its installation and upkeep. Active Vent is designed to make both easier, but getting the full benefit means choosing the right product for the job, fitting it correctly, and using the feature that sets it apart: a removable insert you can pull out to inspect and clear the cavity. This hub pulls together the practical steps and points you to the detail on each.

Choosing the right vent

Active Vent is built as a whole-home system rather than a single product. The Active Weep Vent serves the cavity in an external masonry wall, draining water and letting the cavity breathe. It measures 10 × 65 × 100mm and fits into a brick perp joint that has been chased out (not drilled). The Active Trickle Vent handles background ventilation for the rooms themselves and is designed to support Building Regulations Part F. It is 15mm in diameter and 75mm long, and fits into a 16mm hole drilled through the window frame: one section goes in from outside, one from inside, and they click together. We recommend at least two per window. Which you need depends on whether you are tackling a wet cavity, stuffy rooms, or both. Browse the full range and specifications in the shop or on the products page.

Installing it correctly

Correct spacing and clean detailing are what make a vent actually work. NHBC guidance is that where fair-faced masonry is supported by lintels, weep holes should be at a maximum of 450mm intervals, with at least two above each opening (NHBC Technical Extra, Issue 18). Where those vents go, and why, is covered in our NHBC cavity ventilation guide. For the step-by-step fitting method, follow the installation guide.

A few principles carry the most weight:

• Keep the cavity clean as you build: most blockages start as dropped mortar.
• Position vents where water actually collects: at the base and over cavity trays above windows and doors.
• Do not seal a cavity shut in the name of insulation; it still needs to drain and breathe.

Inspecting and maintaining

This is where Active Vent’s removable insert earns its place. A standard weep vent is hard to inspect or clear once blocked, and current cavity surveys do not require anyone to check the base of the cavity for debris, so blockages go unnoticed. Active Vent’s insert can be pulled out so the cavity can be looked into and any dropped mortar or debris flushed back out, then refitted. That means a wall can be checked before a damp problem appears, not after.

If you want the building science behind why any of this matters (why a wet cavity leads to damp indoors and wasted heat), start with the science of cross-ventilation.

A quick owner’s checklist

• Pick the right product: Active Weep Vent for the cavity, Active Trickle Vent for the rooms. See the products page.
• Fit to the correct spacing using the installation guide.
• Keep cavities clean during and after the build.
• Use the removable insert to inspect and clear the cavity periodically, especially after nearby building work.
• Fixing a wider damp issue? Read the NHBC cavity ventilation guide first.

Ready to specify or buy? Head to the shop, or get in touch for advice tailored to your property.