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What Are Weep Holes?: Relieving Pressure on Basement Walls

Weep holes drilled into the basement wall.

No homeowner wants water lurking behind their foundation walls, as moisture causes various problems, from mold growth to structural damage.

Weep holes offer a simple solution to safeguard your home from these moisture threats. These openings direct water away from your foundation, ensuring your home remains safe and dry.

Let’s discuss weep holes and their role in the crucial waterproofing process.

Weep Holes: What Are They?

water flowing through weep holes

Weep holes are small openings strategically placed in a building’s exterior, such as brick cavity walls, retaining walls, or windowsills. Their primary function is to allow water to drain from within the building envelope, preventing moisture buildup and minimizing the risk of water-related damage like wood rot and mold. While not always connected to a foundation drainage system, some designs may incorporate weep holes that channel water to a French drain or a perforated pipe system.

When Are Weep Holes Necessary?

Several factors may necessitate weep holes. These include:

  • CMU Block Foundation: Weep holes benefit CMU block foundations by releasing and relieving trapped water and pressure buildup within the hollow blocks.
  • French Drain System: Properly installed weep holes and French drains work together to remove water from behind foundation walls. The weep holes relieve hydrostatic pressure within the CMU blocks, allowing water to drain into the French drain system and directing the water away from the foundation.
  • Frequent Basement Leaks: Water intrusion needs to be addressed, as weep holes alone won’t solve leaks caused by cracks, faulty waterproofing, or other factors.

Frequent basement leaks may require more than weep holes to solve the problem. A thorough assessment and professional, tailored waterproofing solutions may be necessary to address the issue and keep your basement dry. Contact a foundation repair expert for a free inspection if you notice basement water or leaks.

Weep Hole Installation Types

Weep holes are essential for draining water from within building envelopes, preventing moisture buildup and potential damage. Here is a breakdown of various weep hole installation methods and how they suit different wall constructions.

Open-Head Joints

This method involves omitting mortar from the vertical joint between bricks during construction, creating a small gap at the top of the joint that allows water to drain. It is a traditional method used for brick cavity walls that allows trapped water within the cavity to escape. However, open-head joints are noticeable and may require additional flashing details like metal or plastic to prevent water infiltration.

Tube Inserts

Pre-cut plastic or metal tubes are inserted into the mortar joints during construction, creating a drainage channel for water through the wall. Tube inserts are used for brick or block cavity walls and are less noticeable than open-head joints. However, tube inserts can become ineffective due to potential mortar debris clogging during installation. Tube inserts require careful placement and might not be suitable for thicker walls.


Small holes are drilled into the mortar joints or concrete block walls. Weep hole screens are installed to prevent insects and debris from entering while allowing water drainage. Drilling is suitable for concrete block foundation walls, retaining walls, and existing brick walls where other methods are not feasible. Professional installation is recommended to ensure proper placement and avoid damaging the foundation. Experts can navigate around the rebar and steel reinforcements, prevent damage to underlying utilities, and maintain the structural integrity of the building.

Consider Building Codes and Wall Materials

When installing weep holes, it’s essential to consider local building codes, which may specify their size, placement, and screening requirements. The chosen method should be compatible with the wall material and its thickness. Drilling existing walls or handling thicker walls is best left to experienced professionals. This ensures proper placement and helps avoid structural damage.

Weep Hole Alternatives

Traditional weep holes, though effective, can have drawbacks such as allowing insects to enter or becoming clogged. Here are some alternative systems for managing water within building envelopes:

crew member with vapor barrier sheet in front of house

Vapor Barriers

Vapor-permeable membranes, installed behind exterior cladding such as brick or stone, allow water vapor to escape from the cavity while preventing bulk water from entering. This approach helps the wall system “breathe” and dry out naturally, potentially reducing or eliminating the need for large weep holes.

drainage matting in a crawl space

Drainage Matting System

Drainage matting systems consist of a dimpled plastic mat installed behind the exterior cladding. The dimples create an air gap that allows water to drain down to weep channels at the base of the wall, preventing water from accumulating within the cavity.

crawl space encapsulation with dehumidifier

Crawl Space Encapsulation System

Weep holes can enhance crawl space encapsulation methods, creating a more comprehensive moisture management strategy. Encapsulation involves using a vapor barrier, drainage matting, and a dehumidifier to address crawl space moisture from the ground and air. By adding weep holes to the foundation walls, any water that seeps through can drain away toward a sump pump and through a drainage system.

crew member installing basement waterproofing sump pump drainage

Basement Waterproofing Methods

Weep holes complement basement waterproofing methods, creating a comprehensive defense against moisture. While a sump pump, drainage system, dehumidifier, and vapor barrier manage the majority of water intrusion from the ground and air, weep holes handle water seepage through the foundation walls. These small openings drain the water, preventing accumulation behind the vapor barrier and avoiding issues like mold growth.

The best alternative for your project depends on factors such as climate, building materials, and budget. Even with proper waterproofing, some water might still find its way through the foundation walls, making weep holes beneficial for drainage. In areas with high water tables or heavy rainfall, weep holes can serve as a crucial backup for a drainage system. Contact a foundation repair professional like JES to determine the most suitable system for your home.

Protect Your Home with Professional Waterproofing from JES

JES work truck

Do you think your home may benefit from weep holes or other waterproofing measures? JES Foundation Repair offers free inspections, ensuring a precise and customized waterproofing solution. If you reside in Virginia, DC, Maryland, West Virginia, or northeastern North Carolina, contact us today to learn more.

    Contact Us For Your Free Inspection

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    Basement Waterproofing FAQs

    Waterproofing a basement can take anywhere between a single day and a full week. The more extensive, constructive types of waterproofing will take significantly longer than applying sealants, for example. If you’re working with a contractor, be sure to talk to them about how long they see the process of waterproofing your basement taking.

    If you’re waterproofing your basement on your own time, do your research in advance and make sure not to take on a project that’ll consume more time than you’re willing to commit.

    It’s recommended to regularly check your basement, especially after heavy rainfalls or during seasons with increased precipitation. Monthly checks can help you spot early signs of water intrusion, allowing for timely intervention. 

    Basements can be susceptible to water intrusion during any season. However, periods of heavy rain or melting snow, such as in spring or after severe weather events, can heighten the risk. It’s also worth monitoring during prolonged rainy periods or rapid snowmelt. 

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    Shaye Glisson

    Shaye Glisson

    Shaye is an SEO Content Writer for Groundworks with over twelve years of experience creating helpful content across various industries, including home services and retail. She is a Gulf Coast native and writes from her firsthand knowledge of the area's hurricane and flood impacts on the local community. In her free time, Shaye enjoys exploring the local food and music scenes.

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