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cavity wall weep vent

What is a Weep Vent?

Have you ever spotted small gaps, resembling missing mortar, between the bricks of your external wall? While the impulse might be to fill them in, these inconspicuous openings play a critical role in protecting your home from moisture damage. Introducing weep vents, the unsung heroes of UK building regulations.

Looking to Buy? Order Weep Vents online here.

So what is a Weep Vent, and what does it do?

Weep holes, also known as weep vents, are purposefully created gaps between bricks in cavity walls (the space between the inner and outer brick layers). These small openings serve as drainage channels, allowing trapped moisture within the cavity to escape. This prevents water buildup, which can lead to dampness, mold growth, and structural deterioration.


The Essential Role of Weep Vents in Cavity Walls

Cavity walls, a common feature in brick-built homes constructed after the 1920s, play a crucial role in maintaining thermal comfort and preventing moisture ingress. This guide delves into the specific function of weep vents, essential components within cavity walls that ensure proper drainage and ventilation.


Understanding Cavity Walls

A cavity wall comprises two separate brick leaves with an air gap in between. This gap provides several benefits:

  • Thermal insulation: The air gap acts as a natural insulator, keeping homes warmer in winter and cooler in summer.
  • Moisture control: The cavity allows for the dissipation of moisture that penetrates the outer brickwork, preventing it from reaching the inner wall and causing dampness.

The Role of Weep Vents

Weep vents are small openings typically located at regular intervals near the base of the external wall and above openings like windows and doors. These vents serve two primary functions:

  • Drainage: They allow any moisture that accumulates within the cavity to drain out, preventing waterlogging and potential damage to the brickwork and insulation.
  • Ventilation: Weep vents enable air circulation within the cavity, promoting drying and preventing the buildup of condensation, which can also contribute to dampness.


Building Regulations and Weep Vents

In the UK, building regulations like Document J of the Building Regulations 2010 mandate the use of weep vents in cavity walls. This ensures proper ventilation and drainage, minimizing the risk of moisture-related problems like dampness, mold growth, and structural deterioration.


Types of Weep Vents

Weep vents come in various materials and designs, with the most common being:

Open weep vents

These are simple gaps between bricks, often covered with a mesh to prevent insects from entering.

Closed weep vents

These vents incorporate a plastic or metal grille that allows for drainage and ventilation while keeping out insects and debris.

Fire-resistant weep vents

These are required in specific buildings for fire safety reasons. They are made from non-combustible materials to prevent the spread of flames through the cavity wall in case of a fire.


Maintaining Weep Vents

It is crucial to ensure that weep vents remain unobstructed for proper functioning. Regularly check for and remove any debris like cobwebs or leaves that may block the vents. Additionally, avoid filling the weep vents with mortar or sealant, as this can trap moisture within the cavity and negate their purpose.


External Wall Vents

NHBC Requirements are for weep vents to be provided at a maximum of 450mm intervals when lintels support masonry.

Weep vents have a long product life and tend to be manufactured from uv stabilised polypropylene.

Available in a variety of colours to match your mortar colour to blend into the aesthetics of your building.


Beware of Large Nest Building Insects

Be sure to check where weep holes or vents are formed as they can be used as an entry point for insects.

Whether a retrofit or new build, remember to include your wall weep in your project list to meet relevant british standards and to avoid costly updates further down the line.

There are some fantastic videos, demonstrating installation. Check this one out from the bestbricky:


Please note we are not affiliated with Best Bricky and are not responsible for any advice provided by Best Bricky. 


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