Ever heard of weep holes? Well, if you’re buying a new home, you are about to. Weep holes are topping the list of items to inspect during a pre-purchase building and pest inspection on brick houses as they can cause expensive moisture damage if ignored.
In this blog post, we discuss the purpose and problems homeowners can experience with weep holes in masonry walls.
Key Takeaways
- Weep holes are small gaps in brickwork designed to allow moisture drainage and air circulation within wall cavities.
- Without functioning weep holes, your property can suffer moisture damage, mould growth, and even termite infestation.
- During an inspection, weep holes must have at least 75 mm clearance from the ground and must not be blocked by garden beds or decking.
- Blocked or incorrectly built weep holes can invite pests such as rodents, termites, and wasps into your home.
- Regular inspection and maintenance—especially after heavy rain or flooding—are essential to prevent damage and maintain ventilation.
What are weep holes and why are they so important?
Weep holes are small gaps or vents in the brickwork in the brick veneer walls of a house. They serve two main purposes; to ventilate the interior and drain out any moisture.
Without properly functioning weep holes, your property can suffer a long line of moisture-related defects such as mildew, mould, and even “leaky building syndrome.”
How to identify weep holes
Identifying weep holes in brick walls is an important part of maintaining your property. Here are some steps you can take to identify weep holes in your brick home:
- Look for gaps in the mortar between the bricks: Weep holes are typically small gaps in the mortar between the bricks, located near the bottom of the external wall. These gaps are usually no wider than 3/16 of an inch and can be difficult to spot from a distance.
- Check for patterns: Weep holes are usually located in a pattern of one every few feet along the bottom course of the brickwork. You can usually see these patterns by looking closely at the mortar joints.
- Look for vents: Some weep holes are covered by vents, which can be made of metal or plastic. These vents are designed to allow air to circulate in the cavity behind the bricks while keeping out debris and insects.
- Use a flashlight: If you’re having trouble identifying weep holes, shine a flashlight along the bottom of the brickwork. This can help you spot the small gaps in the mortar.
- Check the plans: If you have access to the original plans for your home, they may show the location of the weep holes. This can be especially helpful if you’re having trouble identifying them visually.
If you’re having trouble identifying them, it’s a good idea to call in a professional to help you locate and maintain them.
Ventilation
Adequate ventilation is crucial in a healthy home. Without it, the risk for mildew and mould growth and weakening the internal walls and other material is significant. Prolonged dampness can lead to indoor mould growth (fungal) and creates a conducive environment for termites and timber pests.
Mould exposure can also lead to severe human health effects, and especially for people with Asthma or a mould allergy. Damages caused by overlocked weep holes are costing Australians millions in repair every year.
Drainage
Any water that enters the home (leaks, flooding/rain events, condensation) will need to escape somewhere to not cause damage. This is especially important in sub-tropical areas of Australia where the high moisture in the air is causing water to flow from the wall cavity after a heavy deluge.
The recent floods in NSW and QLD demonstrated how important sufficient weep holes are in flood-resilient homes. As the water subsides, weep holes enable the moisture to correctly disperse from the home and prevent mould and rot in the frame. Regular checks of your weep holes should be part of any flood smart plan.
What is the inspector looking for?
According to Australian Standards and to avoid any obstructions, weep holes should have at least 75mm clearance from the ground. During an inspection, the inspector will make sure that no raised path, garden bed or decking is blocking the weep holes. This is so they won’t hinder moisture from escaping the house. They will also be on the lookout for any mud tracks or weeping honey surrounding the opening. Weep holes lower than 75mm from the ground are considered invitation to termites and other small pests.
Problems with weep holes: rodent & termite entry
Weep holes can cause some problems to home owners if not manufactured and maintained correctly. The holes should be a certain size and as mentioned above, be located at a certain height above ground. This is so rodents and small insects won’t be able to get into the house through the weep holes. Swarming bees, wasps and mice are among other unwelcome visitors that might make an appearance if the weep holes are not correctly manufactured. If you are worried about your weep holes and pest and termite activity, do not attempt to cover or obstruct the hole yourself. A professional inspector can suggest purpose built screens to keep pests out while still maintaining adequate airflow.
Another aspect to be aware of if you are the owner of a house with weep holes, and especially in bushfire zones, is that they provide access to embers which can have devastating consequences. As a result, the Building Code for bushfire-prone areas (AS3959:2009) has specific requirements for ember screening in weep holes in masonry construction. If you have any concerns, speak to your local inspector today!
Get a professional in
At Inspect My Home, our qualified building inspectors always check for signs of elevated moisture during a building and pest inspection. Our team of professional property inspectors are trained to carry out thorough pre-purchase property inspections.
All services are followed by an easy-to-understand report, emailed 24 hours after the inspection. Call today on 1300 337 447 or conveniently book online.
Frequently Asked Questions
What is a weep hole?
A weep hole is a small gap in the mortar between bricks, typically found near the base of an external wall. Its purpose is to allow trapped moisture inside the wall cavity to drain out and to promote air circulation, preventing dampness, mould, and structural damage.
Why are weep holes used in brick walls?
Weep holes are essential for both ventilation and drainage. They release moisture that accumulates within the wall cavity from condensation, rain, or leaks, and they help maintain healthy airflow. Without them, water can become trapped, leading to mould, mildew, and damage to internal walls and materials.
What happens if weep holes are blocked?
Blocked weep holes stop moisture from escaping the wall cavity, which can cause water buildup, dampness, mould, and even structural weakening. In severe cases, it can also attract termites and timber pests that thrive in moist conditions. Never block or cover weep holes yourself—have a professional inspect and clear them safely.
How far apart should weep holes be?
According to Australian building standards, weep holes are typically spaced every few bricks apart (about 1.2 m intervals) along the bottom course of brickwork. This even spacing ensures consistent drainage and ventilation throughout the wall cavity.
Can mice get in weep holes?
They can, if the openings are too large or too close to the ground. Weep holes that are lower than 75 mm above ground level or lack proper screening can allow small rodents, insects, or even bees and wasps to enter. A qualified inspector can recommend purpose-built mesh screens that block pests while maintaining airflow.
Do weep holes need to be cleaned?
Yes, but with care. Over time, debris, soil, or vegetation can block weep holes. Cleaning should be part of routine property maintenance—but never seal them off completely. If you’re unsure how to clean them safely, contact a professional building inspector to assess and maintain them.
