Weep Holes

A weep, weep holes, or a weep brick is a small opening that enables water to drain from an assembly located on the bottom of the object to permit the drainage, these holes should be sufficiently sized to overcome surface pressure.

The weeps could also be essential for a retaining wall so water can escape from the retained earth, thus lowering the hydrostatic load on the wall and preventing moisture harm from freeze/thaw cycles.

Under such conditions, the weep consists of small diameter plastic, clay, or metal pipes which extend through the wall to a layer of porous backfill.

Sometimes, the weeps arranged immediately for water that has entered an assembly from behind the surface, it is made in metal windows and a glazed curtain wall to avoid interstate condensation.

Function of weep holes:

If the structure is located about the water desk, there is no possibility of water accumulating behind the wall, so a weep hole will not be required.

However, when the construction is situated below the water table and further pressure of water on the structure works is larger than the saturated pleasures or pressure of the earth, the weep hole is required.

Case-1: Water Table is Below the Structure – No Weep Holes Required.

The water table is below the structure so only earth pressure is considered when designing the structure.

Case-2: Water Table is above the Structure -No Weep Holes Provided.

When water is mixed with the soil, the saturated pleasures or earth pressure submerge, which is lower than the saturated pressure but the water pressure is higher than the saturated pressure.

So this types of structures, soil and water pressure should be considered when designing.

Case-3: Water Table is above the Structure and Weep Holes are provided.

If the water table is above the structure, but weep holes are provided in the structure, then major pressure of water is eliminated by using weep hole, the pressure due to water relieves the pores.

The height of placement of the hole plays an important role, as the height of the weep hole, the greater structure is pressurized by water.

Weep holes are provided using sand gravel that ensures the proper functioning of those holes, the variety of holes is provided primarily based on the dimensions of the structure and the height of the water table.

The height at which the weep hole depends upon the utmost potential height of the construction of the water or the natural groundwater table.

Types of Weep Holes:

1. Open Head Joint Weep Holes:

This weep hole are formed by eliminating the mortar from the vertical joint between the bricks.

These walls are the same size as the typical joint spacing, the specific space between the open hand joints is done at 21-inch intervals.

This is done by using a plastic weathered structure to prevent rain as well as entry into the pores, drip is included on the front lip to aid drainage.

2. Cotton Rope Wicking Weep Holes:

This weep hole are made using a 12-inch rope are placed in pairs and the other end extended to the wall of the cavity.

The water behind the wall is absorbed by the cotton and evaporates to the other side, this process is slower than ordinary row holes.

3. Tubes Weep Holes:

The tube weep hole are formed using hollow plastic or metal tubes, they are spread around 16 inches.

This tube is positioned at a slight angle to allow water to drain, it must be ensured that the angle will not be too flat.

Advantages of Weep Holes:

  1. Weep holes provide a gap that permits drainage for moisture from the back of the wall by penetration, capillary action, or leakage.
  2. It is installed in brick masonry to protect the air behind the wall from mildew, dry rot, and moisture which affects the life and performance of the building.
  3. They are generally found within the outer masonry of cavity wall, above the home windows, and doors in cavity walls.
  4. They are offered at regular intervals to permit moisture escape, the recommended distance between row holes is 450 mm.
  5. From the engineering perspective, the weep hole gives reduction from hydrostatic pressure or water pressure on the walls.
  6. This reduces structural design demand for water and earth pressure by reducing the thickness and reinforcement needed.
  7. The weep hole also reduces buoyancy and uplift on the structure, making it potential to construct a lighter structure without any uplift associated stability issues.

Disadvantages of Weep Holes:

  1. Blockage of Weep Hole due to Trash Mortar:

When hole are installed in the brick masonry, the mortars squeeze between successive courses of bricks and drop down into the weep hole.

This can partially or completely prevent weep hole by scraping mortar.

2. Pest Entry through Weep Holes:

Weep hole can provide access to pests such as rodents and insects.

The entry point into the interior of the building may be through ventilator fans and holes for plumbing and electrical purposes below the lights.

To overcome this problem, baffled vents can be installed.

3. Obstruction in Airflow:

To overcome the above problems of insect penetration and garbage mortar and even to make the weep hole more pleasing, the weep hole may not provide the necessary flow of air to properly ventilate the internal brick wall.

Also read Surge Tank, Fish Ladder & Weir


Weep holes are necessary to allow rainwater to exit the house, if water remains in the bricks, it leaks into the interior walls.

Hello, I'm Rahul Patil founder of Constructionor.com, I had studied B.E. Civil. This blog provides authentic information regarding civil structures, equipment, materials, tests & much more.

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