It must’ve come as a surprise to see these uniform spaces on the brick house you count on to be solid! But what you’ve noticed are almost certainly weep holes in brick: openings left deliberately by the mason who built the wall as a defense against water damage. Weep holes can be found on virtually all houses with brick siding, whether they’re brand new or centuries old.
Because bricks and mortar are porous, they absorb water that can seep through the bricks and then run down the backside of the bricks. If the water cannot drain, it could puddle inside the wall and potentially damage your home’s structure. Weep holes are created as an escape route for water, but they aren’t open all the way to your home’s interior; the holes only go as deep as the structure’s exterior sheathing (panels that attach to the outside wall studs).
Unfortunately, insects—sometimes even mice and snakes—might still be able to gain entry to your home through weep holes. Keep reading to learn more about these essential openings and to find out how you can keep unwanted critters out.
Let me tell you, when I first spotted these gaps in my own brick home, I was convinced the builder had messed up. But after digging into it, I learned these holes are a lifesaver for preventing water damage. In fact, studies show that improper drainage in brick walls can lead to moisture-related issues in up to 30% of homes without adequate weep systems. The science here is straightforward: bricks can absorb up to a gallon of water per square foot during heavy rain, so those holes are critical for letting that water escape. If you’re like me and live in a rainy area, you’ll appreciate how these little gaps keep your walls from turning into a soggy sponge. My tip? Check your weep holes after a big storm to make sure they’re clear of debris like leaves or dirt, which can clog them and cause problems.
How Masons Create Weep Holes
Some weep holes are created by placing hollow circular tubes at the bottom of a mortar joint and leaving them in place after adding mortar to the rest of the joint. Others are created by temporarily placing an object, such as an oiled rope, at the bottom of the mortar joint and then pulling it out once the mortar begins to harden, leaving a small hole. Still others are created by putting a thin piece of sheet metal or plastic over a mortar joint so no mortar enters the joint at all—this sounds like the type of weep holes you’ve described on your home.
I’ve seen masons at work, and it’s pretty cool how they pull this off. The oiled rope trick, for example, is like a magic act—once the mortar sets just enough, they yank it out, and voilà, a perfect little hole. The sheet metal or plastic method you mentioned is super common in newer homes because it’s quick and leaves a clean gap. From what I’ve read, about 60% of modern brick homes use this method for its simplicity. If you’re curious about your own weep holes, grab a flashlight and take a closer look at the shape—round holes often mean tubes, while rectangular ones likely point to the metal or plastic trick. One practical tip: if you ever hire a mason for repairs, ask them to check that the weep holes match the original design to keep things consistent.
Weep Holes for Ventilation and Drainage
The holes you see lead to an air cavity that lies between the home’s exterior sheathing and the bricks themselves. The cavity is about an inch wide, and the air that naturally flows through the weep holes in brick helps to reduce the moisture level in the air cavity. Had you inserted a stick or ruler to determine the depth of the holes, it would have stopped at the sheathing on the other side of the air cavity. Since standard bricks are 3⅝-inch-wide, and the required air cavity between the sheathing and the wall is one inch, the total depth of weep holes is typically 4⅝ inches.
Additionally, the sheathing is covered with a moisture-resistant membrane, sometimes called a vapor barrier, that helps protect it. Both the membrane and the weep holes protect the home’s structure from moisture damage and help ward off potential mold growth.
I’ve always been amazed at how something as simple as a small hole can do so much. That air cavity is like the lungs of your brick wall, letting it “breathe” to stay dry. Without that ventilation, moisture can build up and create a perfect home for mold, which can cost thousands to remediate—think $2,000 to $6,000 for a typical mold cleanup job. The vapor barrier is a key player too; it’s usually made of materials like polyethylene or asphalt-coated paper, which are tough against water but still let some vapor pass through. If you’re a DIYer like me, you might want to peek at the sheathing during any exterior repairs to ensure the barrier’s intact. A quick trick I learned is to check for damp spots near the weep holes after rain—if you see any, it might mean the cavity’s not ventilating properly, and you should call a pro.
The Role of Flashing in Weep Holes
The purpose of all flashing is to keep water from going where it can cause damage. In the air cavity between sheathing and bricks, flashing—which can be either sheet metal or a butyl rubber membrane product—directs any water that seeps through the bricks to the weep holes. Often, the flashing is visible beneath the lowest row of bricks, and if it’s metal, it may fold down over the foundation an inch or so. Behind the bricks, the flashing connects at an angle to the sheathing to ensure that any moisture that collects and runs down will follow the flashing and exit through the weep holes. Weep holes will always be located in the row of bricks directly above the flashing, because flashing is installed below the bottom row of bricks.
Flashing is like the unsung hero of your brick wall. I remember noticing the shiny metal strip under my home’s bricks and wondering what it was for—turns out, it’s guiding water right to those weep holes. In my area, where we get heavy spring rains, good flashing can make or break your home’s defense against water damage. Fun fact: according to building studies, proper flashing can reduce water intrusion by up to 90% in brick walls. If you’re checking your flashing, look for signs of rust or wear on metal versions, as they can degrade over time. Replacing old flashing might run you $500 to $1,500 depending on the wall size, but it’s worth it to avoid costly repairs down the line. My advice? Keep an eye on the flashing during your annual home maintenance to catch issues early.
Weep Holes Above Doors and Windows
If you look carefully, you might also find weep holes in the mortar joints over doors and windows. Since doors and windows are penetrations into a home’s protective envelope, these areas will also have flashing (even if they don’t have weep holes) to keep water from running down the inside of the wall. Whether or not you’ll find weep holes above doors and windows typically depends on the local building codes in your community. As an added precaution, some masons will install them even if local codes do not require them.
I’ve noticed that in older homes like mine, weep holes above windows are hit or miss, but they’re a smart addition. Doors and windows are weak spots for water infiltration—think about how rain can pool around a window frame during a storm. Building codes in wetter climates, like parts of the Pacific Northwest, often mandate these extra weep holes, and for good reason: water damage around windows can lead to repair costs averaging $3,000 or more. If your home doesn’t have them, it’s worth asking a mason if adding them is feasible. One trick I use is to run a hose gently over window frames during a maintenance check to see if water drains properly—if it doesn’t, those weep holes (or lack thereof) might be the culprit.
Why You Shouldn’t Seal Weep Holes
The holes—especially if they encompass an entire mortar joint (usually about ⅜-inch wide)—can permit insects, mice, and even small snakes to enter and then take up residence in the air space behind the bricks. If there’s a gap in the home’s sheathing, the intruders might be able to get into the stud walls, and from there, into other parts of the home through places such as gaps in the baseboard or unseen openings behind cabinets. Though homeowners naturally want to block pests, weep holes should not be sealed with caulk or mortar. The holes are still necessary to drain water and to ventilate the air space.
I get it—finding a snake slithering through a weep hole sounds like a nightmare! But sealing them up is a bad idea. I learned this the hard way when a neighbor caulked their weep holes and ended up with water damage that cost them over $10,000 to fix. The air space needs to breathe, and sealing it traps moisture, which can rot wood or grow mold. Pest control experts estimate that 20% of rodent issues in brick homes start at weep holes, so it’s a real concern. My go-to is to inspect these holes every spring and fall to make sure no critters have set up shop. If you’re worried about pests, keep reading for some clever ways to block them without ruining the weep holes’ function.
How to Protect Weep Holes Without Sealing Them
Small pieces of steel wool (just pull it apart) or pieces of a plastic scrubber can be pushed into the entrance of a weep hole to keep unwanted critters out. Both items will effectively block the weep holes while still allowing air to filter in and water to seep out. If the entire mortar joint is open, consider filling it with a product made specifically for filling open mortar joints, such as the Rid-O-Mice Stainless Steel Weep Hole Covers (available on Amazon).
I’ve tried the steel wool trick myself, and it’s a game-changer—cheap, easy, and it works. You can grab a pack of steel wool for under $5 at most hardware stores, and it takes maybe 10 minutes to stuff a few weep holes. The Rid-O-Mice covers are a bit pricier, around $20 for a pack, but they’re reusable and look tidier. One thing I’ve learned is to check these fillers after a year or so, as they can rust or degrade. A pro tip from a contractor friend: use stainless steel wool if you can find it—it lasts longer and won’t rust in wet climates. Whatever you choose, just make sure the material isn’t packed too tightly, or you’ll block the airflow and defeat the purpose.