Foundation drainage

Foundation drainage is an externa

l drainage system that is installed on the outer side of the f

oundation wall and near the base of the wall and is covered with a layer of gravel to drain excess water entering the foundation.

Types of foundation drainage

French colander
Base discharge

Foundation drainage components and performance

The main component of a foundation drain is a perforated pipe laid around the exterior foundation, which captures excess water and drains it to a storm sewer or sump or pit some distance from the building.

Holes are thousands of tiny slits that allow excess water to enter the pipe and exit the base of the structure. The pipe is usually covered with a permeable mesh filter, which helps prevent dirt from entering the pipe. It is then covered by layers of sand in graduated sizes and finally filled with soil.

Gravel allows water to flow down the drain pipe without allowing dirt and debris to clog it. The weeping tile (inner pipe) is installed in such a way that it moves away from the structure and takes the water to the main sewer network.

Consideration of foundation drainage design

To design a foundation drain, several factors must be considered to ensure effective drainage. Some factors are discussed below:

1: Required code

The International Residential Code (IRC) requires drainage around all concrete or masonry foundations that retain ground and enclose habitable or usable spaces below grade. However, very well-drained soils are the exception, and mixes such as sand and gravel do not require drainage.

2: Drainage boards

In rainy areas, drainage boards are used to quickly drain water to the perimeter drainage by installing them on the foundation wall. This prevents hydrostatic pressure from building up next to the wall.

3: Evacuation of materials

Perimeter drains should be made of rigid drain tile or perforated pipe. Although flexible corrugated plastic tubing can be used, care must be taken to avoid crushing it during refilling.

4: Wet

The amount of soil moisture that is placed near the foundation of the building has a great effect on the drainage of water from the foundation because the amount of moisture depends on the type of soil placed.

5: Trees

According to the US Department of Housing and Urban Development, trees should not be planted closer to a building’s foundation than their final height. This prevents the roots of the trees from filling the environmental drains and prevents the tree from absorbing all the water from the soil.

6: Placing drain pipes

Drain pipes should be placed next to the base, the best point is near the base. Although the tile does not need to be sloped, low spots (which can be used with mud) should be avoided.

Types of foundation drains

French colander

In this type of foundation drainage, a perforated pipe is used, which is placed next to the foundation wall structure. The slope of the pipe is kept away from the structure. Then filling with internal materials like gravel is done for easy flow of stagnant water from the surface to the drain pipe.

Base discharge

This is a very effective drainage system. A pipe is installed around the perimeter of the foundation walls at the foundation level. This pipe collects any water that leaks from the top of the foundation into the basement and drains it through the walls of the foundation.

Advantages of foundation drainage

It prevents the accumulation of water near the foundation and hence reduces the risk of settlement. Stagnant water may also encourage mosquito breeding and kill plants.

Soil erosion can be reduced by installing foundation drains.

Proper drainage can help remove toxic and harmful organisms from stagnant water.

Disadvantages of draining the foundation

Installing a drainage system is a costly investment. It requires skilled and professional workforce.

Using a perforated pipe has the disadvantages of regular clogging due to the accumulation of materials in the pipe. Hence the maintenance of foundation drainage is horrendous.

Contamination of water bodies – According to the study, subsurface drainage systems can carry nitrate through drain pipes and direct it into water bodies such as streams, rivers and lakes.

PVC geomembrane or HDPE geomembrane for isolation

Strip geodrain for vertical drainage of walls

Dimple sheet drains for drainage

Geotextile for filtration and protection of the geomembrane sheet

PVC rundle for geomembrane sheet installation

Dimple sheet gasket for installing the egg shoulder drain

Among the advantages of using geosynthetic material compared to other old methods, the following can be mentioned:

Reduction of excavation operations

Reduce operational costs

High speed of project completion

Higher system quality

Steps to perform drainage under the foundation

Excavation

Dealing with the level of underground water and digging a temporary well to prevent mud in other places and continuous pumping to the space outside the workshop,

continuing the digging operation to reach the level under the foundation and directing the water to the temporarily dug wells and drying the foundation floor exposed to air.

And Aftab, choosing the location of two or three deep wells in the form of rods and digging them in the corners of the foundation and outside it called pits, and installing several branches of high pressure spiral pipes to prevent the well body from falling and blocking it,

and installing floor screeds for permanent water pumping. from it and making a line to guide the underground water with the help of the main and secondary peripheral channels and the appropriate slope during channeling with the help of an excavator to guide the water from these channels with the help of a series of pipes,

pre-drilled in the body of the pipe. that the provision of piles under the foundation is to prevent asymmetric settlement and non-interference of pipes and piles

Work is done in the body of the pipe so that the pile is predicted under the foundation to prevent asymmetric settlement and non-interference of pipes and piles.

Arin Khak Iranian Company, with decades of experience in the field of foundation drainage, is ready to provide all kinds of services to you dear ones. To get free advice on all geosynthetic products and services in this field, contact our consultants.