Why are brick weep holes so important?

Brick weep holes are a critical component of any brick home and are incredibly important to maintaining its structural integrity and health.

If you’re a homeowner who’s never heard of brick weeps before, or you’re not sure about what exactly they do, read on for a detailed guide about them and their importance.

We’ll tell you everything you need to know about brick weep holes, why you should protect them with brick weep hole covers, and how you can ensure yours are well-maintained.

Brick weep holes appear as a vertical space between two bricks.

Table of contents

A weep hole in a brick wall just above the foundation.

What are brick weep holes?

A brick weep hole is an intentional opening in the brickwork of a home that allows moisture to escape through drainage or ventilation.

They look like small round or vertical gaps in the mortar between bricks and are usually evenly spaced apart.

Without brick weep holes, water can become trapped and cause significant structural damage over time.

Locating brick wall weep holes

Brick wall weep holes can be found in several places on a brick home where water is likely to penetrate.

They are most commonly located at the base of brick cavity walls, but can also be found around doors, windows, and along retaining walls.

Brick weeps work with a structure’s drainage system and are often paired with flashing to prevent water infiltration.

Flashing is a thin sheet of metal or other impermeable material that is installed at the junction where the wall meets the foundation.

It creates a watertight seal that diverts water away from the building envelope and brick weep holes are its exit point.

Two brick wall weep holes positioned above a door.

How does water get into brick walls?

It may come as a surprise to you to learn that brick buildings are not waterproof. In fact, brick walls can be highly permeable, meaning they can absorb large amounts of water. So how exactly does water get into brick walls?

Heavy rain falling in front of a house.

Heavy rain events

Heavy, driving rain can cause water to enter a brick veneer wall through gaps around the door or window frame joints, cracks in the mortar joints, as well as through the bricks themselves.

Flash flooding due to this rainfall can place further pressure on these weak points and cause brick wall cavities to fill up with water.

A water pipe leaking and spraying causing internal flooding.

Internal flooding

Internal flooding caused by leaking rooves, pipes, and toilets can also cause brick walls to become saturated with water.

If the building’s masonry weeps or drainage system is comprised in any way, this water may be unable to escape and remain within the cavity.

Water seeping up a brick block wall caused by capillary action.

Capillary action

Capillary action is the process of water flowing in a narrow space and moving from a wet area to a dry one. Also known as rising damp, it can be a major cause of moisture penetrating brick walls.

Without masonry weep holes, or if the existing drainage system is blocked or broken, capillary action can result in the water becoming trapped inside the cavity wall.

Droplets of water shown forming on a surface from condensation.

Condensation from heating and cooling

Condensation from heating and cooling systems can also cause moisture to accumulate within brick cavity walls.

If there are no brick weep holes and not enough ventilation present in a building, warm air from the inside of the property will mix with cold air from the outside, causing droplets of water to form on cooler surfaces like the internals of brick veneer walls.

A drainpipe on a brick wall with ice coming out of it and snow in the background.

Snow and ice

Finally, snow and ice can assist brick walls to absorb water because of the weight of these elements coupled with their melting process.

This can quickly overwhelm a building’s drainage system, leading to moisture buildup and eventual seepage into the brick wall cavities.

The problems moisture can create

Once water is inside and trapped within a brick cavity wall, it can cause a variety of issues that may lead to costly repairs

This phenomenon is also known as ‘leaky building syndrome’ and has been a major issue in both New Zealand and Canada in recent years where it caused billions of dollars in damage.

So what are some of the problems that trapped moisture can create?

Structural damage

The first and most serious issue is structural damage. Pooled water that is trapped within a cavity wall without brick weeps provides the optimal environment for fungal growth.

This fungal growth can eat away at the timber framing and other materials within the wall over time, a process that the occupiers are usually unaware of while it’s taking place.

Also known as rot, this process of decay causes the material to break down and the resulting damage makes the structure weak and prone to failure.

Sadly, rectifying the problem can be an extremely difficult, time-consuming, and expensive process as major changes need to be made and numerous specialists involved.

Structural damage inside a brick cavity wall.
Mold and mildew growing on internal white wall.

Mold and mildew

In addition to structural damage caused by rot, fungal growth can manifest as mold and mildew which can pose serious health risks to the building’s occupiers.

Mold and mildew thrive in spaces where there is poor ventilation, excess moisture, and warm air, which are all conditions that can be present within a cavity wall without brick weep holes.

These fungal organisms can cause serious respiratory problems, headaches, and skin irritation for many people, particularly the elderly and young children, as well as those with existing allergies, asthma, and weakened immune systems.

The difficult issue here is that the occupiers may not be aware of these fungal growths as they lay obscured behind the wall, and the only way to remove these organisms is by completely removing all of the affected materials.

How do brick weep holes help?

Brick weep holes help prevent structural damage caused by rot, and other problems associated with mold and mildew, by improving a brick cavity wall’s drainage and ventilation.

These small openings are just part of a larger system responsible for the moisture management of a building but are crucial for its functioning.

Let’s look at each of the solutions this system provides.


Weep holes in brick walls are an important part of a building’s drainage system and provide an outlet for water to escape from the brick wall cavity.

In a well-constructed building, an effective building wrap will be installed and combined with a flashing system to protect the internal wall elements and foundations.

Together, these channel any water that has entered the structure down towards the masonry weep holes which then act as an exit point out to the building’s external drainage system.

Without brick weep holes, a cavity wall would not drain effectively and pooled water could result in structural damage from rot.

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


Weep holes in brick cavity walls also assist a building’s ventilation by allowing air to move freely in and out of the structure.

Good ventilation helps ensure the brick wall cavity remains dry by allowing moisture within the air of the space to escape and can assist with the drying of materials that have become wet.

This movement of air can also help prevent condensation from forming on the internal walls from the use of heating and cooling systems, which can create another water source inside the cavity.

Without brick weep holes, the air within a cavity wall can become stale and provide the perfect breeding ground for fungal growth such as mold and mildew.

Bricklayer making brick wall weep holes during construction .

Making weep holes in brick walls

Weep holes in brick cavity walls are typically created during the construction process, though they can be retrofitted to existing buildings usually at a significant cost.

For new homes, a bricklayer will use a former to create the space that will eventually become the brick weeps.

A former is a special hollow device that is inserted between bricks at the location of the intended brick wall weep holes.

The bricklayer will then lay mortar and further brickwork around the former resulting in a clean finish and well-created brick weep hole that drains effectively.

Formers are a preferred tool over other methods that involve crude tools to create holes that lack uniformity and can instead cause problems with drainage and ventilation.

The problems brick weeps create

Despite all the incredible advantages of having functional brick weep holes in your building, they can create several problems that in themselves can be difficult to manage. Let’s take look at the most common of these.


Brick wall weep holes can provide an entrance for pests such as rodents, insects, and termites into the building.

These pests can cause serious damage to the building by damaging wires, insulation, and critical structural materials inside the wall cavity.

They can also pose a health risk to the occupiers. Feces from rodents and cockroaches, nests from swarming bees or wasps, and bites from spiders and insects are all potential problems from the access that brick weep holes can give these pests.

Mouse climbing down a brick wall.


Brick weep holes can also become obstructed with debris over time from both internal and external sources.

Blockages can result from mortar during construction, soil and gardening material from adjacent gardens built too close, and from leaf litter or nests that become lodged in these spaces.

These obstructions can prevent brick veneer weep holes from functioning correctly as drainage and ventilation can be impeded causing many of the issues discussed above.

A blocked brick weep that is completely closed.


Brick house weep holes can also provide a direct channel for hot embers to travel inside to your wooden materials during catastrophic wildfires.

Embers are known to travel incredibly long distances during major fires and these can land miles in front of the fire front due to strong winds.

Strong updrafts from within your home can then suck these embers in through your brick weep holes where they can access the easily combustible timber materials of the building.

Several sparks and a flame erupting from a masonry weep hole.
A caulking gun being used to seal brick weep holes.

Protecting your masonry weep holes

Some of these problems, particularly the pest issue, may lead some homeowners to consider sealing weep holes in brick walls at their homes.

This is not recommended as it will impede drainage and ventilation leading to many of the problems outlined above, and create a much bigger problem than that which is trying to be solved.

Instead of completely sealing your brick weep holes, you can instead use a weep hole cover that can protect against pests, blockages, and embers while still maintaining the utility of your masonry weeps.

If your home wasn’t built using formers that have integrated grates, you can purchase retrofit brick weep hole covers to get the job done.

A protected brick weep hole with mouse trying to enter.

Products such as Weepa’s brick weep hole plugs can be easily inserted into existing weep holes in brick cavity walls and provide a secure fit that protects against pests and external intrusions.

In addition to using a protective cover or screen, you should also inspect and maintain your masonry weep holes regularly.

To do this, plan a regular time to inspect all of your brick weep holes for any evidence of obstruction and debris.

Remove any blockages using a small wire brush, coat hanger wire, or even a vacuum cleaner which can effectively suck materials out of the space.

FAQs about brick weep holes

What is a weep hole in brick?

A weep hole in brick is a small opening on a masonry wall that allows water to escape a wall cavity. Brick weeps are often found near the foundations but can be found near windows and doors.

What are weep holes in brick for?

Weeping holes in brick houses assist with the drainage and ventilation of a building. They allow water to drain out of cavity walls and provide ventilation that helps prevent water damage.

Can you add weep holes to brick?

Adding weep holes to existing brick walls is possible but the process can be incredibly difficult and expensive. A specialist can assess if retrofitting brick weep holes at your home is viable.

How to clean weep holes in brick?

Weep holes in brick can be cleaned using a small wire brush or a hooking tool made from wire. Vacuum cleaners can also be an effective tool to clear hard-to-reach debris.

Is water coming through brick weep holes normal?

Weep holes are designed to provide drainage so some water is normal. If you have large amounts of water consistently blowing through your weep holes it may be evidence of flooding or another problem.

No weep holes in brick walls. Should I be worried?

Many structures have been built without weep holes, or worse, have had these filled in after construction. Whether you should be worried depends if your building has been impacted by moisture damage.

A long brick cavity wall shown with perspective.

So in summary

Brick weep holes are intentional openings in brickwork left by builders to assist with the drainage and ventilation of the structure.

Water can enter a brick home in various ways including through rain events, localized flooding, and condensation.

If this moisture is unable to escape, it could lead to structural damage and issues with mold and mildew that can be expensive to repair and dangerous to the health of the home’s inhabitants.

Weep holes in brick walls help remove this water but can create new problems, such as pest infestations, which can be resolved by using a quality cover or screen.

If you’re looking to protect your brick weep holes while maintaining their functionality, be sure to check out the Weepa Protector Weep Hole Screen which offers numerous benefits to households of brick homes.

Shop Now