What are Weep Holes?

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  • Written By: Mary McMahon
  • Edited By: O. Wallace
  • Last Modified Date: 14 August 2019
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Weep holes are holes in the exterior walls of a structure which allow water to vent to the outside, ensuring that it cannot accumulate behind the walls. They also permit air circulation, which makes the area inside the walls hostile to molds which can damage structural elements of a building. These holes are used on masonry and stucco homes, both of which are prone to water problems if they are not built and maintained properly.

The installation of weep holes occurs during the construction process, when the courses of masonry over the foundation are being laid. The holes are made by leaving open cracks unfilled with masonry cement. Some masons use tubes surrounded by mortar to create a less obvious crack, and the hole can be covered with netting or similar material to keep pests from getting inside the wall. As the name implies, these holes literally weep when water accumulates inside the wall, allowing the water an outlet.

The weep holes must be installed above grade. If the holes are below grade, water, dirt, and other materials can enter the walls through the holes, and this is not desired. This is why the holes are typically established at the foundation line, as the foundation comes up above grade. In the case of a house surrounded by grade changes, as might be the case with a house built into a hillside, it may be necessary to install weep holes at different heights.


In addition to being installed around the foundation, these ventilation holes should theoretically also be placed around windows and doors. These openings can provide a way for water to get in between the walls, making adequate ventilation and drainage necessary to prevent problems. While flashing is designed to prevent water penetration, it cannot be successful all of the time. Without weep holes, water which creeps in through the cracks will be trapped in the walls, where it can lead to mold, rot, and mildew.

Installation of weep holes may be mandated under the building code for some types of structures in certain regions. A knowledgeable contractor should be aware of when this feature is required. Once a structure is finished, installing these holes is extremely difficult, so it is important to confirm that they are or are not necessary before construction has progressed too far. In some regions, contractors who fail to meet code when they build a structure can be forced to fix the structure or to pay for remediation to bring the structure up to code.


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Post 5

Window frames need 'weep' holes, while multi paned glass panels are sealed. Brick above windows and doors need weep holes. As for 'weep' holes in the shower? Not sure what that is.

Post 4

Windows do not have weep holes. Windows with two or more panes of glass are sealed units. When the seal is broke, condensation forms between the panes. If there was a weep hole, condensation would form. What you have is seal creep, not lack of weep holes.

Post 3

@donasmrs-- I'm no expert but I also think that having new weep holes drilled is your best bet. Don't try to do it yourself though because if you drill the wrong spot, you'll just make things worse.

You will have to have someone do it for you. They will have to remove the shower tiles, drill the weep holes and put the tiles back.

We had a similar issue with our basement weep holes. My brother knew someone in the construction business who came and did it for us. It made a huge difference! Our basement had a musty odor before and that disappeared.

Post 2

Has anyone had an issue with weep holes becoming clogged? What did you do about it? Did you have them "de-clogged" or did you just have new weep holes put in?

I have a problem of excessive humidity and mold in my bathroom, particularly around the shower. I'm pretty sure that it is caused by clogged shower weep holes which were unfortunately placed below grade.

I'm not sure what I should do about it. Having it de-clogged is probably not the best idea since it will just get clogged again over time. If I have new weep holes put in above grade though, that might resolve the issue altogether.

Any experts here who can help me decide what to do?

Post 1
I didn't know this until recently, but windows require weep hole vents too.

My neighbor had PVC (polyvinyl chloride) windows installed last month. A few days after the installation, it rained and condensation formed on all of his windows. But this wasn't the kind you could wipe away.

Apparently, PVC windows have multiple layers of glass for insulation purposes. And since they forgot to make make weep holes between the layers, the water got into the middle layer and caused condensation. Three days passed without rain and my neighbor still couldn't see through his windows!

He complained to the manufacturer and had all of his windows replaced. Weep hole vents seem like such a small detail, but they're important. Having witnessed what my neighbor went through, I've definitely learned that.

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