Cavity Wall Ventilation Accessories: Weep Vents, Airbricks & Peep Vents

Understand cavity wall ventilation and drainage accessories, including weep vents, airbricks and peep vents, and how their functions differ.
By JJ Building Materials
2 min read

Cavity walls need carefully planned moisture and ventilation details. Weep vents, airbricks and related accessories may all appear in brickwork, but they perform different functions. Selecting the correct component starts with understanding whether the detail is intended to drain water, ventilate a space or provide a route through the wall. This guide explains how common cavity-wall and brick ventilation accessories work together.

Weep Vents: Moisture Drainage

Weep vents are installed where water collected within a cavity needs an outlet. They are commonly associated with cavity trays above openings and at other designed drainage locations.

Airbricks: Airflow

Airbricks provide a larger ventilation opening. The TRADE Airbrick Vent 9 x 3 is used where the construction requires airflow through masonry, such as into an underfloor void.

Peep Vents

The TRADE Peep Vent Terracotta provides a small, discreet opening that can integrate with brickwork where that product type is specified.

Do Not Confuse Drainage with Ventilation

A cavity drainage outlet and an underfloor ventilation opening are not the same. Choosing the wrong accessory can leave the intended moisture or airflow route incomplete.

Cavity Trays and Weeps

Where a cavity tray collects water, weep outlets need to be positioned so the water can discharge externally. The tray should direct moisture toward the vents rather than leaving low points with no outlet.

Underfloor Airflow

For suspended floors, airbricks should connect to the underfloor void and be distributed according to the ventilation design. Internal walls and later alterations should not block the route.

Appearance and Brick Matching

Visible vent colour can be chosen to sit more discreetly within red, buff or other brickwork, but never sacrifice the correct component type for appearance. Keep the grille or slot unobstructed.

Installation Checks

  • Confirm what each vent is intended to do.
  • Follow the required spacing and positions.
  • Keep all openings clear of mortar.
  • Coordinate with DPCs, cavity trays and floor levels.
  • Check external ground and paving will not block airflow.
  • Inspect vents before handover.

Shop Brick Ventilation Accessories

Browse brick accessories at JJ Building Materials, including TRADE Weep Vents, peep vents and airbrick vents.

FAQs

Do cavity walls need airbricks?

Only where the building design requires ventilation through the wall, such as to an underfloor void. The cavity itself has separate moisture-management details.

Are weep vents for airflow?

Their primary role is drainage of moisture from cavity details.

Can I paint a vent?

A coating must not block the opening. It is usually better to choose a suitable colour initially.

Why are vents installed above windows?

Where a cavity tray sits above an opening, weep vents can provide outlets for collected water.

Should I inspect vents after pointing?

Yes. Mortar can obstruct openings, so a final check is good practice.