What is a weep hole and what do they do?

If you’ve ever noticed the small openings within your home’s walls, windows, or brickwork, you may have wondered what they’re for.

These tiny openings are known as weep holes, and they play an incredibly important role in your home’s drainage system and its structural health.

Below we will explore the function of weepholes, what happens if you cover weep holes, the potential problems they create, and the various ways to solve these.

Let’s start by taking a closer look at what is a weep and why they’re necessary.

A weep hole shown in a open head joint between bricks.

Table of contents

Diagram showing what is a weep hole. Shows a cavity wall with labels for weep holes, flashing, sheathing, air barrier and foundation.

What is a weep hole?

A Weep hole is a small opening that allows water to escape a building envelope or structure. They help to prevent water accumulation and can also assist with ventilation and reducing hydrostatic pressure. You can find weep holes in concrete block walls, brick cavity walls, window frames, retaining walls, and many other places where water accumulation is a problem. By allowing water to escape, they can prevent damage to the building or structure.

What is the purpose of weep holes?

The purpose of weep holes is to provide an outlet for water to drain and escape a building or structure. They can also assist in the ventilation of cavity spaces and relieve hydrostatic pressure from barriers such as retaining walls. Below are the three main advantages that they provide.

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.


Weepholes are an important component of a building or structure’s drainage system.

Moisture can enter a building in several ways, including through direct penetration, such as heavy rain or flooding, as well as water rising via capillary action.

Once inside, this water can damage the surrounding structure and cause erosion or rot over time if it can’t escape.

A structure’s flashing diverts any water that has entered, out towards the weep hole where it can exit into the external drainage system.

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


Weep holes also help with ventilation within cavity walls by allowing air to flow in and out of the building.

This is incredibly important as it helps to reduce moisture levels in the air inside and can also assist in drying rates of the internal structures if they have been impacted by water.

When you don’t have enough ventilation, mold and mildew can easily grow and cause significant damage to your structure as well as pose a health risk to its occupants.

Ventilation and airflow are improved with the use of weep holes in walls and can help to prolong the life of your building.

Large cracks on a retaining wall caused by hydrostatic pressure.

Hydrostatic pressure

Weep holes protect a structure’s stability by helping to reduce hydrostatic pressure, which is a force generated from water held behind a barrier such as a retaining wall.

This pressure can be detrimental as it can cause stress and strain on the surrounding structures, potentially leading to cracks, movement, and other damage.

Furthermore, the water can eventually find its way into the structure and cause other issues including; damp walls, mold and mildew, and even flooded basements.

Weep holes function to provide an escape route for water held behind the barrier, which in turn reduces the hydrostatic pressure and prevents structural damage.

Types of weep holes

Weepholes come in all shapes and sizes and can be found in many places where water can penetrate a building or structure. Below are the three most common types.

Brick weep holes

Weep holes in brick walls usually appear as small vertical spaces that are left during construction in the mortar of brickwork.

They allow moisture to escape from brick cavity walls, which helps to prevent the buildup of water and condensation.

Look at a brick masonry weep wall and you’ll find these gaps spaced at intervals specified by building regulations, but you may also find them above windows and around doors.

They can be easily identified by their small size and vertical orientation.

Brick weep holes appear as a vertical space between two bricks.
A window weep hole located at the bottom edge of the frame.

Window weep holes

A window weep hole is a small hole found near the bottom of external window frames.

Windows are frequently exposed to the elements and water from rain or home watering systems can easily make its way into the frame of windows.

Storm window weep holes allow any water that has entered the frame to escape and drain away helping to prevent rot and water damage to the frame and sill.

Not all windows have these devices with some designs using a sloped sill instead to channel water away.

Retaining wall weep holes

Retaining wall weep holes are large gaps present in the lower foundations of earth-retaining structures.

These foundation weep holes allow water to escape from behind the retaining wall and help prevent hydrostatic pressure from building up during periods of heavy rain or flooding.

In addition, retaining wall weep holes can also make it possible to build lighter structures because they can reduce buoyancy and uplift forces which in turn improves stability.

Without them, the lateral forces from water build-up can cause stress on the wall structure causing damage and leading to it potentially failing.

Retaining wall weep holes on a curved stone block garden wall.

Issues with weep holes

While weep holes are designed to help with drainage, ventilation, and hydrostatic pressure, they can also create problems of their own. Below are the main issues that they can cause.


Weepholes are vulnerable to blockage due to debris which can prevent water from draining away and reduce ventilation. This completely impedes their function.

Loose mortar during construction is a common cause of clogged weep holes in brick walls as it can fill the space and create blockages.

Dirt, paint, and caulk are regular culprits of blocked weep holes in windows and as these openings are quite small, it doesn’t take much material to cause problems.

A blocked weep hole shown.

Insects, rodents and pests

A weep hole creates a potential entry point into your building for pests such as mice, insects, and spiders. Even snakes are known to use these entry points!

Once inside, these pests can cause damage to a building’s internal structures and pose a health risk to its occupiers.

Termites in particular are known to use weepholes as an entry point into homes, especially when timber or garden waste is positioned close to them, and they can cause serious and costly damage.

A cockroach crawling along an outside wall.

Wildfire embers

A weep hole can act as an entry point for embers during wildfires or other fire events.

As strong winds usually accompany these events, hot embers and sparks can travel great distances and these entry points provide the perfect pathway for them into your home.

Embers can be sucked into weep holes through strong updrafts and once inside the consequences can be devastating.

A wildfire ember causing a flame inside a weep hole.
A caulking gun being used to seal up and block a weep hole.

Sealing weep holes in brick walls

In an attempt to prevent any of the above issues, many homeowners will desperately resort to sealing them up using paint, caulk, or mortar.

However, this is a terrible idea as it effectively traps water and moisture inside the structure and can severely impede ventilation.

Sealing basement weep holes can lead to serious damp problems and rot caused by mold and mildew. This can cause extreme damage, often without the occupier knowing it is happening.

Sealing window weep holes can cause excessive condensation and water build-up leading to rotting of the window sill and frame.

Sealing retaining wall weep holes can cause stability issues for the wall as any water behind the wall cannot escape which in turn increases hydrostatic pressure on the structure.

It’s best to avoid using sealants altogether as this can create bigger problems than the ones they were designed to solve. But if you can’t seal them, how do you prevent the issues mentioned above?

A weep vent installed in a wall with a protective grill.

How to protect your weep wall

Quality weep hole covers are the best way to protect these openings while maintaining their functionality.

They are designed to allow air and water through while at the same time preventing debris, pests, and embers from entering.

Available in a range of materials and sizes to suit different types of holes, they come in different forms also known as weep hole screens, weep vents or weep hole mesh.

They can be an effective solution for the problems posed by house weep holes in cavity walls, window frames, and retaining walls.

A brick weep hole screen can help reduce external debris that causes blockages and many offer removable covers that allow you to clean and maintain the hole from internal obstructions.

Covers also offer protection from pest entry through the use of screens and grates. Some even offer protection against termites using special bifenthrin-infused materials.

Stainless steel covers that are heat and fire-resistant also offer protection against embers and sparks caused by wildfires.

Even with a cover in place, weep holes require general maintenance to keep them functioning properly.

A stainless steel weep hole cover with insertion tool ready for installation.

Weep hole maintenance

Inspecting your weep holes should be part of your regular home or building maintenance program and involves checking them for obstructions, debris, and blockages.

Removing vegetation, dirt, mortar, and other debris from weepholes is essential to keep them functioning as intended. This can be done with a vacuum cleaner, small wire brush, or hooked tool crafted from coat hanger wire.

If covers are installed, it’s important to inspect these also for damage or blockages. Some may need replacing if their fit is no longer secure.

A wire brush held by a hand.
A weep hole shown near a garden bed with leaf litter and bark clogging it.

Pipe cleaners and toothpicks can make for excellent tools to de-clog your window weep holes and ensure they are clear and free-flowing.

Make sure you keep your gardens and plants well away from your external weep holes at ground level as well as any stacks of timber.

Vegetation and leaf litter can easily cover them and impede their function while timber can also provide an access point for termites or other pests.

Maintenance is key to ensuring your weep holes stay functional and provide adequate drainage and airflow.

FAQs about weep holes

How do weep holes work?

Weep holes work by providing a pathway for water and air to escape from cavity walls, window frames, and other structures. This helps reduce condensation and mold growth in concealed areas.

Where are weep holes located?

Weep holes can be found in windows, brick walls, retaining walls, and anywhere that water can penetrate. They are typically located at the base of the structure to make use of gravitational force.

Is water coming out of weep holes ok?

Yes they're designed to drain water from a building but the amount depends on the weather and climate conditions. An excessive amount of water may indicate a major leak which shouldn't be ignored.

What is weep hole ventilation?

Weep hole ventilation refers to the process of allowing air and moisture into a cavity wall or window frame to prevent condensation and mold growth.

Are weep holes necessary?

Weep holes are necessary for the proper functioning of many structures, such as cavity walls and retaining walls. Some older structures were built without them as they pre-date building code requirements.

Do weep holes need to be covered?

Weep holes in cavity walls can be covered with screens to help prevent them from being used by pests. They should never be completely sealed as this can impede drainage and ventilation of the cavity.

What are weep holes in windows?

Weep holes in windows are small openings usually located at the bottom of window frames. They act as drainage channels and help prevent water pooling in hidden areas which can cause damage.

How often should a weep wall be inspected?

A weep wall should be inspected regularly and any debris cleared away. Checking them when you perform other frequent home maintenance activities, like mowing your lawn, can create a regular habit.

Where are the weep holes on sliding glass doors?

The weep holes on sliding glass doors are typically located at the bottom of the door frame. They can help drain any water or moisture that accumulates in the track and around the glass.

A weep wall exposed and open.

So in summary

Weep holes serve an important role in your building’s drainage system and can be found in walls, windows, and retaining walls.

They help to prevent water accumulation, assist with ventilation and reduce hydrostatic pressure, all of which help to maintain a healthy building structure.

Despite all their advantages, weep holes can create problems of their own with blockages, pests, and wildfire embers.

Despite this, they should never be sealed as that can create even bigger problems.

The best way to protect them without sealing is to use a quality cover and to inspect them regularly as part of a home maintenance program.

Want to protect your weep holes while maintaining their functionality? Check out our premium Weepa Protector Weep Hole Screen product today.

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