The Importance of Weep Holes in Masonry | Mace Masonry Ltd.

The Importance of Weep Holes in Masonry

February 3, 2021

What are weep holes?


Weep holes are small gaps in the masonry, about the size of a mortar joint, that are located around the exterior of a brick property close to the foundation wall and around windows and doors. They are essentially designed to let water escape freely from behind the masonry and provide ventilation.


Air spaces are required between the internal cavity walls and exterior façade to allow air to circulate and prevent moisture from building up. The weep holes are designed to work with this air space by letting any water out of this area efficiently and freely once it lands on the cavity tray or flashing at the bottom of the wall or any water stop point. Bricks are porous so they do allow a small amount of moisture to be adsorbed; this moisture runs down the back of the wall and needs to be let out, if it’s not let out this can cause serious implications.


Weep Holes



Why are weep holes required?


The weep holes often get overlooked by homeowners, sometimes they even have them filled in by installing mortar or caulk it, because they do not understand the significant purpose of them. Homeowner’s may want these holes filled to prevent mice or bugs getting into the property, but often a product called a weep vent can be installed so there’s no hole but a ventilated plastic piece installed into the hole.

It’s quite shocking that these required weep holes even get overlooked and have seen them missing on both newly built homes and on repair projects, which are completed by trained professionals. So this is why it’s important to bring their purpose to people’s attention.


Weep Holes



Water needs to escape – simple; as soon as water enters an area it needs to go somewhere or else the area will start to deteriorate i.e. cause water damage – this is essentially what the importance of weep holes are for. There’s a number of damages that missing weep holes can cause, more specifically it’s usually an expensive and costly fix. The deterioration of the damage will be a slow process, we’re not talking about a flow of water; it will not occur right away after the masonry has been built or repaired, it’ll happen over a few years – but the damage is 100% certain to occur. Usually when the damage is visible is when it’ll need repairing, preventing further deterioration is not possible at this point.



How should they be installed?


The Ontario Building Code requires weep holes to be installed at the correct locations on all masonry. See an exert with requirements below: Required Weep Holes

(1) Weep holes spaced not more than 800 mm apart shall be provided at the bottom of,

(a) cavities in cavity walls, and

(b) cavities or air spaces in masonry veneer walls.

(2) The cavities or air spaces described in Sentence (1) shall include those above lintels over window and door openings required to be flashed in conformance with Article

(3) The weep holes required in Sentence (1) shall be in a location such that any water that collects in the cavity or space will be directed to the exterior of the building.




Types of damage caused by no or incorrectly installed weep holes


The types of damage associated with missing weep holes varies depending on the location of the missing weep holes, here’s a few examples of what I’ve experienced:


  • Efflorescence: Having no weep holes means one thing: water can not escape efficiently. This means water is sitting behind the brickwork without an easy route to escape, and water will always find a way to get out. So usually when there isn’t a purposely installed hole, it will soak through the skin of the brick to the exterior. This will start to appear as efflorescence on the face of the brickwork; a white milky colour. Any signs of efflorescence means water is causing an issue (more can be discussed on this topic on another masonry blog post at a later date!). You can try and clean efflorescence before it gets too bad to repair – usually only in the early stages.


  • Spalling brickwork: After efflorescence has set in, it will crack and peel the faces of the bricks off. This will result in the cracked bricks needing to be replaced entirely. Brick replacement can be costly if there is a high number of bricks to be replaced. Any cracked masonry should be addressed and looked at to find the route cause, a lot of the time it could be because weep holes have not been installed.


  • Internal water issues: If water can not escape freely to the exterior of a property, it’s going to find it’s way out some where else. Unfortunately, it may not be through the brickwork but actually the other directions – towards the interior of your home. Not having weeping holes correctly installed can cause water damage inside your home.


  • Rusty and sagging lintels: one of the most common places to install weep holes, other than the first course of brick above the foundations, is over doors and windows. Steel lintels are installed over masonry openings i.e. windows and doors, to support the brickwork load above. When weep holes are not present, the water has no way to escape and then sits on the lintel. What happens when water and steel come into contact for a long period of time – rust! The lintel will rust, when this happens the steel is weakened and at it’s worst point it will sag as the week lintel now struggles to hold the masonry load above. We often complete a window repair or door repair due to no weep holes having been previously installed and have even seen a new lintel repair completed with no weep holes in the soldier course of brick above them.


  • Bulging bricks above window/door: Commonly associated with the rusting lintel as mentioned above, the brickwork over the lintel it will look like it’s bulging upon visual inspection. It almost looks like the water is pressuring to be released from behind it. The only way to resolve this, is by removing these bricks entirely, replacing the lintel and laying new bricks correctly with the correct moisture protection and weep holes. The image below shows this exact issue that requires attention, in particularly the middle window you can see the lintel sagging.


Weep holesSource: Mace Masonry’s own image


So next time you’re buying a property, take a look around the exterior of the brickwork at the lower courses of brick to see if these weep holes are present. If not, you’ll know the type of damage that could be occurring. Next time you’re repairing a masonry structure, whether it be rebuilding lower sections or replacing lintels, ensure these weep holes are installed, this ensure you are completing a permanent and precise repair for your client whilst maintaining the structural integrity of the home.


Mace Masonry can complete all your window repairs and door repairs in Toronto, as well as lintel repairs, brick replacement and ensuring your home has correct weep holes installed.

Structures from individual units laid in and bound together by mortar.

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