Weep Holes in Retaining walls: Importance, Function, Advantages & Disadvantages of Weep Holes

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In this article, we will discuss weep holes in retaining walls.



Weep holes are small openings that might be circular or rectangular in shape to permit rainwater from the retaining walls, buildings, cavity walls etc. Weep holes help to decrease buoyancy and uplift the structure and make it structurally strong and stable. The weep holes should be sized suitably to decrease the surface tension.



  1. Weep Holes in Retaining walls  

Weep holes are kept in masonry walls, retaining walls, underpasses, wing walls and other ground-draining structures to pass accumulated water through walls.

Weep holes have an opening that permits the drainage of any water that may arrive from the backfill of the wall through penetration, capillary action or leakage. Weep holes kept in brick masonry also work as a ventilator to permit air to the back of the wall to control mildew, dry rot and dampness which in turn affect the life and performance of the building. Weep holes are commonly seen in the outer masonry of cavity walls.

They can also be located above cavity walls. They are kept at common intervals to allow the out of water. The suggested gap between weep holes is 45 cm. From an engineering standpoint view, weep holes reduce hydrostatic pressure or water pressure on retaining walls.

This decreases the structural design demand of the water and earth pressure by decreasing thickness as well as reinforcement requirements. With this, weep holes also decreases the Buoyancy and uplift on the structure making it feasible to build lighter structures without any uplift-related stability problems.


Weep Holes in Retaining walls



  2. Importance of Weep Holes  

When the walls are prepared above the water table then there will be no possibility of accumulation of water behind the wall. In this case, there is no necessity for the condition of weep holes.

But if the structure is built below the water table then there will be surplus pressure of water will be originated on the structure and it is necessary to provide weep holes to pass water through it.

The weep holes are the small openings that are provided mostly in the retaining walls, wing walls, external brick walls, underpasses, and bridges to release the hydrostatic pressure which is originated.


Importance of Weep Holes



  3. Types of Weep Holes  

There are different types of weep holes which are categorized according to their uses

1. Open Head Joint Weep Holes

Open-head joint people are provided by Living out water from the joints. These types of weep holes are open holes of the same size as the typical spacing of the joints.

The open-head joint process is one of the common and effective methods which are used to evaporate water from the cavity. Depressing which is provided between the open hip joint weep holes is 24 inches.


Open Head Joint Weep Holes


2. Cotton Rope Wicking Weep Holes

Cotton rope-wicking weep holes are formed by using a rope of 12 inches in length. This type of weep hole is placed in the joints and the other end is extended to the cavity wall.

The water from the back of the wall is absorbed by the Cotton and on the other side, it gets evaporated. This process is low as compared to other types of weep holes.


Cotton Rope Wicking Weep Holes


3. Tubes Weep Holes

Tube wells are formed with the help of hollow plastic or metal tubes which are spaced around 16 inches from each other. The Tube weep holes are installed at a slight angle to allow water to drip out easily and care should be taken that the angle should not be too steep.

Sometimes a Shallow layer of gravel is laid to prevent the water from dropping from the blockage of the tube weep holes.




4. Corrugated Channels

Corrugated channels are the latest technology in the weep holes which helps to quickly drain off water from the multiple channels. It is installed at the bottom side of the bed joint of the mortar.


Corrugated Channels



  4. Functions of Weep Holes in Retaining Walls  

There are different use of weep holes in a cavity wall which are listed below:

a. The major use of providing weep holes in the walls is to decrease the hydrostatic pressure which is formed in the wall.

b. Weep holes in the retaining wall asset to drain the rainwater out from it.

c. Weep holes are given at the bottom side of the retaining wall which permits water to drain from the water lodge on the retaining wall.

d. Weep holes in the retaining wall asset to decrease the buoyancy and uplift the structure and make it structurally strong and stable.

e. Weep holes in the retaining walls assist to control any further damage to the retaining wall.

f. Weep holes save the retaining wall from dampness.

g.It also works as the most essential objective of ventilation in the retaining walls.


Functions of Weep Holes in Retaining Walls



  5. Advantages of Weep Holes  

The advantages of weep holes are as follows:

a. Permit water to drain from the water lodge on the retaining wall

b. Decrease hydrostatic pressure originated due to water lodge

c. Protect damage and moistness

d. Enables dampness control

e. Supply ventilation of the internal wall cavity


Advantages of Weep Holes



  6. Disadvantages of Weep Holes  

a. Blockage of Weep Holes due to Trash Mortar

When holes are kept in the brick masonry. The mortar comes out between the successive courses of bricks and drops down in the weep holes. This can outcome in partial or total closure of weep holes by waste mortar.

b. Pest Entry through Weep Holes

Weep holes can give access to pests such as rodents and insects. The entrance point to the internal of the walls can be through downlights ventilator fans and holes for plumbing and electric use. To decrease this issue, a Baffled vent can be provided.

c. Obstruction in Airflow

To decrease the above issues of pest entrance and waste mortar and to even create the weep holes more pleasing, weep holes may not keep the necessary flow of air to properly ventilate the internal brick wall.


Disadvantages of Weep Holes


Hope you liked our article weep holes in retaining walls.



Read Also: Slump Test

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