What are weep vents and what is their purpose?

Weep vents may seem like a minor detail in the construction of a building, but they play an important role in the drainage and ventilation of a structure.

Just like weep hole covers for brick walls, they can afford some protection from external threats like pests, but it is their role in protecting your home’s internal structure that is of great importance.

Without them, a building’s structural integrity and the health of its inhabitants may be at risk due to the various problems these vents can prevent.

In this article, we’ll take a deep dive into brick weep vents and examine their function and purpose in more detail.

White brick weep vents installed in light coloured brickwork.

Table of contents

A weep vent shown installed in a rendered wall.

What are weep vents?

Weep vents are small devices inserted into masonry cavity walls during construction to form functional holes in a weep wall that help with drainage and ventilation.

They differ from covers and screen products which are retrofit devices installed into existing buildings with exposed weepholes.

They are often used in cavity wall construction in brick, masonry veneer, or rendered cladding, and are available in various sizes to suit the walls they’ll be used in.

The materials of masonry vents vary by brand and by use case to suit; a project’s budget, the surrounding environment, and the type of finish required.

What do brick weep vents do?

A weep vents purpose involves three important functions; drainage, ventilation, and the prevention of pests from entering the cavity. Let’s look at each one of these more closely.

Diagram showing how weep hole drainage works with moisture and water running down the cavity walls, over the flashing and out of the weep holes.


Brick weep vents help with the drainage of masonry cavity walls by providing a path for water to escape the building envelope.

They work in tandem with the building’s flashing which protects the internal structures and directs water down towards the masonry vents where it can exit into the external drainage system.

Weep hole vents help to prevent the build-up of water in the wall, which can lead to rot and eventually damage to the structure of the building.

Diagram showing how air moves through weep holes into and up through the wall cavity helping to ventilate it.


Weep vents assist with the ventilation of a building by providing an external opening that helps air flow into the cavity walls and allows it to circulate.

This circulation of air inside the cavity helps to remove moisture in the air, prevents condensation from building up, and can assist with the drying of any materials that have been impacted by water.

Brick weep vents help to prevent stale air and excess moisture which together can provide the perfect breeding ground for mold and mildew.

A mouse lays near an entry point into a brick wall.


Most quality weep vents offer a secure grill or screen across their opening that helps to prevent external pests and insects from entering the space.

Masonry vents offer a direct opening from the outside of the building into the internal drainage system and structures, making them an ideal passage for a wide range of pests to enter or make nests.

A secure grill or screen across this opening stops pests from infiltrating the home where they can cause damage and pose a health risk to its inhabitants.

Why are brick weep vents important?

The above functions provided by weep holes are extremely important to the health of the building structure and the people who live inside. So what can happen if a home doesn’t have brick weep vents, or if these have become compromised and stop functioning?

Structural rot and decay

If water inside a cavity wall is unable to escape from a brick weep vent due to debris or blockage, it can become a breeding ground for fungal growth which can cause extensive and costly repairs.

These growths are known to attack timber framing and other materials within a wall, and over time, they can cause serious decay and even potentially render the wall unsafe and structurally unsound.

The invisible nature of this type of decay means that it can often be too late before the damage is noticed, making weep vents an important preventative measure to ensure that walls are kept in good condition and remain safe.

Structural decay of wooden frame materials from moisture damage.
Mold and mildew growing on a surface.

Fungal growth

If airflow and ventilation become compromised inside a cavity wall, moisture can rapidly accumulate and lead to breakouts of mold and mildew that can pose a serious health risk.

You are more likely to have allergies, asthma, and other respiratory infections if you have mold and mildew present within your home and both young children and the elderly are likely to be more sensitive to these.

Once again, as these growths are inside the cavity and are hidden from view, the home’s occupants may not be aware of the problem for some time, meaning these growths can spread making them even more difficult to remove.

Pest control

If a weep vent doesn’t feature a secure grill or screen, or they have become damaged leading the weep to be exposed, pests can use these pathways as thoroughfares directly into your home.

A large host of pests are known to use open brick weep vents. Rodents such as mice and rats, insects like bees or wasps, along with others including spiders and even snakes can find their way into these openings.

Once inside they may cause damage by chewing on cables and other materials, spread disease through their feces, access your food items, or pose a risk from their bites and stings.

Two mice have their heads sticking out of a weep hole.

Types of masonry weep vents

Quality masonry weep vents can help prevent the above issues, but with such a large range of products on offer, how do you know which one is right for your job? Let’s explore some of the popular options and their use case.

PVC weep vents for new homes

The construction of a new home offers the perfect opportunity to install masonry vents that will work effectively and suit the style of the home being built.

PVC weep vents are an economical option that can be easily installed by builders into brickwork, and result in an attractive finish that promotes cavity ventilation and drainage.

Many designs offer an integrated and hinged grate which offers protection against pests and the ability to inspect or treat the cavity after installation.

Standard Weepa is a PVC weep vent.

Stainless steel for premium finishes

Some homes and buildings require a masonry weep vent design that will blend into premium materials or help accentuate its design.

Stainless steel vents offer a prestigious look that is suitable for a variety of settings, from ultra-modern structures to elegant coastal homes and sophisticated heritage restorations.

Stainless steel weep vents are incredibly durable and attractive, meaning they can be used in exposed locations without the worry of damage or corrosion and can even offer advanced protection against wildfire embers.

Premium Weepa stainless steel weep vent.

Retrofit products for existing homes

If your home was constructed without weep vents being installed, and you have existing weep holes in your walls, you can install brick vent covers on these to provide similar protection.

Retrofit products like the Weepa Protector provide an elegant solution to exposed weep holes in brickwork, helping to secure them from pests and vermin while still maintaining drainage and ventilation of the cavity wall.

The marine-grade stainless steel screen offers an attractive finish and installation is a breeze using the supplied applicator tool.

A weep hole screen product ready for installation.

Cheap alternatives for poor results

Despite all the incredible products available, some homeowners will resort to cheap and crude alternatives to secure their brick weep vents when they are exposed or unprotected by a grill or screen.

Bundles of steel wool or cheap and inferior mesh products are sometimes used to secure weep holes, but often these materials are too thick and can impede drainage and ventilation potentially causing much larger problems with the structure of a home.

Also, these products can be easily dislodged as they lack a way to be installed securely, leaving the hole exposed without the homeowner being aware while pests and critters make their way inside.

A wad of steel wool.

FAQs about weep vents

What does a weep vent do?

Weep vents help water and moisture escape from inside a home. They are installed during the construction of cavity walls and help reduce the risk of structural decay from fungal growths.

Where are weep vents required?

Weep vents are usually required where there is a cavity between two walls such as in brick veneer or double brick constructions. They are typically installed at the base of the wall above the flashing. Building codes or regulations will state their spacing and required locations.

What is the best weep vent to use?

The best weep vent for your job will depend on your specific requirements, such as the type of construction and the level of protection you require. PVC weep vents are an economical option, while stainless steel weep vents provide a premium finish and advanced protection.

Are weep vents necessary?

Weep vents are an important part of construction and they should be installed as outlined by local regulations. They help to provide the drainage and ventilation necessary for a healthy cavity wall.

Weep vent being installed with rendering applied around it.

So in summary

Weep vents play an important role in draining and ventilation and are installed during the construction phase of a building.

They assist drainage by allowing water to escape the building envelope, improve ventilation by helping to circulate air, and can help prevent pests from entering the structure.

If brick weep vents become compromised, several issues can result such as rot and decay, mold and mildew outbreaks, and pest infestations.

There is a wide range of products available on the market, and finding the most suitable involves considering your budget, your use case, and your desired finish.

If you’re looking for a retrofit alternative to weep vents, check out our Weepa Protector Weep Hole Screen product.