How to install drainage for a shallow strip foundation

For a shallow strip foundation, installing drainage is essential to preserving the longevity and integrity of your building project. Water buildup around the foundation can result in problems like soil erosion, hydrostatic pressure, and possible structural damage over time. Proper drainage helps prevent this from happening.

The local climate and soil conditions should be taken into account when designing the installation of drainage for a shallow strip foundation. In comparison to drier or sandy soils, areas with high rainfall or clay soils, for instance, might need more substantial drainage solutions.

Redirecting water away from the foundation is the main objective of drainage installation. The usual method for doing this is to use perforated pipes that are encircled by aggregate or gravel. These pipes gather runoff and divert it to a storm drain or a specially designated drainage area on the property, or any other appropriate drainage outlet.

Excavate the area around the foundation to the necessary depth and width in order to lay the drainage pipes before beginning the installation. The depth will be determined by variables such as the depth of the foundation itself and the nearby frost line, guaranteeing that the drainage system functions efficiently all year round.

After the excavation is finished, a layer of crushed stone or gravel needs to be laid down at the base to create a stable drainage pipe bed. After that, the pipes are connected to the main drainage system and placed with their perforations facing downward to allow water ingress.

What is drainage

Any manipulation of the intricately balanced system that is soil water results in changes and calls for precision and caution. Excavate a trench that passes through the water horizons and becomes a continuous water inflow point in order to build a strip foundation.

Rain and melting water seeping from the surface into the backfill layers complicates the situation. If you don’t take action, you might experience a number of issues like flooded basements, flooding in the neighborhood around the house, and other unfavorable outcomes.

A communication system called drainage is used to take out or drain water from soil layers that are in close proximity to the concrete strip. Pipelines, channels (drains), trays, and other components are included in the complex to help remove moisture or control its amount at a predetermined level.

The excess moisture is either deposited into reservoirs or redirected into low areas of the relief, with the remaining portion being absorbed into the soil’s lower layers.

Do you need drainage with a tape foundation

There is almost always a need for drainage. The seasonal melting of snow and the recurring appearance of rainwater are not negated by the presence or absence of significant groundwater. Usually, the layer of sandy adding (pillow), which is directly under the tape, serves as the drainage system.

Compared to the surrounding soil layers, which form the trench walls, it is more effective at passing moisture. Moisture flows through the pillow without staying behind or harming the base’s material. Water slowly seeps into the earth, sinking to the bottom of the trench.

It is sufficient when there isn’t a steady flow of water from the aquifers in this type of drainage. If there are any active aquifers at the location, you will need to plan for the outflow of incoming moisture and make up for their inflow.

In any case, experts advise installing a drainage system because the trench’s walls and bottom eventually silt up. They cease to absorb water and develop into a sort of reservoir from which moisture cannot naturally escape. This puts the building in grave danger and could lead to its destruction, so developing a drainage system needs to be done carefully.

What forces destroy the foundation?

When moisture comes into contact with a concrete strip, several harmful processes occur:

• Erosion of the sand cushion, which results in subsidence and violation of the integrity of the foundation.
• Water is absorbed into concrete and destroys it from the inside in winter.
• When the temperature drops, the moisture in the soil layers surrounding the tape freezes, expands and begins to put pressure on the base or foundation walls (frost heaving of the soil).

These elements frequently work in tandem, increasing the risk to the foundation and the house as a whole. Gradually, the waterproofing fails and the insulation comes off, aggravating the deterioration processes and negatively affecting the house’s microclimate.

The situation is risky because everything happens slowly and covertly, and the effects aren’t seen until the foundation begins to crumble, fracture, or show other symptoms of failure.

Types of drainage

Different designs for drainage systems exist.

Based on the installation technique, they differentiate:

• Open (surface) type. Moisture is removed by organizing a system of drainage grooves located on the daytime surface of the soil. This option is convenient because it is constantly possible to maintain, clean and change the system design. The disadvantage is the high level of placement, which allows only surface water flows to be drained, bypassing underground horizons.
• Closed (deep) drainage. A closed system is a set of pipelines transporting wastewater to the discharge point. Closed drainage allows you to remove excess moisture from underground sources, but for maintenance or cleaning you have to dig up the pipes, which is only available in the warm season, takes time and requires significant labor costs.

Furthermore, based on the way that water enters pipelines, the following systems exist:

• Perfect. The system is located below the inlet level, water enters from above or from the side. Drainage trenches are filled from above.
• Imperfect. The pipelines are installed above the inflow level, moisture enters from all sides – from below, above and from the sides through holes in the pipe. Backfilling is also done from all sides, i.e.e. the pipe is located at a certain height above the bottom of the drainage groove.

Additionally, there are systems with various functional characteristics:

• Ring. Covers the building with a ring of pipelines, cutting it off from moisture coming from outside. If the influx comes from one side. the formation of an open ring with water collection at the point of its appearance is possible. Can be created after the construction of the house, or in parallel with it.
• Wall-mounted. The system is installed during construction, since the pipelines are installed before filling the sinuses. Provide protection against flooding in basements and basements.
• Reservoir. The most complex system used in areas with an active influx of water or with the presence of clay layers that impede natural filtration. A sand and gravel cushion under a concrete strip is one of the simplified options for creating a reservoir drainage system.

By using an appropriate design option, you can isolate the building from aquifers, eliminate excess moisture, or account for inflows. To do this, specific methods are applied, such as backfilling with clay, which keeps moisture from penetrating the foundation walls and channels it toward the drainage pipes.

It is advised to leave selecting the appropriate drainage system to professionals. This is a challenging task that calls for specialized knowledge and expertise; attempting to solve it on your own may not always yield the desired outcome.

The installation of drainage for a shallow strip foundation is covered in detail in this guide, which is essential to avoiding water buildup that could harm the foundation of your house. We’ll go over everything you need to know to keep your foundation dry and structurally sound, from selecting the appropriate materials to digging and installing the drainage pipes. Whether you’re managing this project or taking on the task yourself, following our simple instructions will help you safeguard your investment and keep a solid foundation for many years to come.

Slope Definitions

The minimum wastewater movement speed determines the drainage pipe slope, which is governed by SNiP.

With pipes of various diameters, you can adjust the inclination to your desired degree:

• With a pipe diameter of 150 mm, a slope of 8 mm per 1 m of length is allowed.
• With a diameter of 200 mm – 7 mm.
• In some areas, an understatement of up to 5 mm per 1 m of length is allowed.

The slope has an upper bound at the same time. It is 150 mm for pipes with a 150 mm diameter. A slope of up to 30 mm/m can be created for unrated sections whose pipe diameter is between 40 and 50 mm, and a maximum slope of 20 mm/m for pipes whose diameter is between 85 and 100 mm.

A slope that encourages the self-purification of water (settling of dirt, sand, and small particles) is required for trays. This will lessen the level of pipeline contamination and prevent traffic bottlenecks and congestion at drainage well outlets.

Preparing the trench

The drainage system trenches are dug to a depth that matches the pipe level. The depth is made with a tiny margin so that the desired slope can be organized.

The drainage system type chosen will dictate the trenches’ orientation and layout, and their width is typically designed to allow pipes to be freely positioned between layers of insulator and filler.

Typically, they excavate up to a width of 30 to 40 cm to make things easier and prevent the walls from collapsing.

Creating a filtration layer

In order to collect water, drainage pipes are corrugated with longitudinal rows of holes. A filtration layer must be placed around the pipes to keep sand and other small particles from clogging them.

The most popular choice is to encircle the pipe with a layer of finely crushed stone that is 10 cm in diameter and covered in a layer of geotextile. It turns out to be a dual filter: the crushed stone layer acts as a secondary purification filter in addition to the geotextile, which keeps sand and organic matter in place.

How is installation done?

Method:

1. A recess is dug in which a container for collecting water is placed. This can be a plastic tank with holes in the bottom or concrete rings. The distance from the house is at least 3-5 m. The depth of immersion should significantly exceed the depth of the foundation, but it should not be brought to the groundwater level. If the house is large, you can use two collectors or more. It is most convenient to install them in the corners. The sides of the container must have holes for connecting drainage pipelines.
2. Drainage pipes are laid next to the tape. If the system is created during construction, the drainage is installed in the same trench as the tape itself. If the system is built later, you will have to dig up the foundation and lay pipelines nearby. The ends of the pipes are inserted into the manifold or connected in series to each other, encircling the foundation on the outside.
3. In some places where problems may arise – connections or transitions – special wells (inspection wells) should be installed. They will allow you to carry out repairs, clean pipes, etc.P.
4. A layer of sand (about 10 cm) is poured onto the bottom of the trench, then a layer of geotextile. Pipelines are laid on it and given the desired slope, for which you can add gravel under the upper edge or simply place a stone.
5. A layer of crushed stone with sand is poured over the pipes. The ends of the geotextile fabric rise and wrap, forming a layer of backfill around the pipe, wrapped in geotextile fabric like a shell.
6. The trench is finally filled with soil.

When the topography permits, water may occasionally be released into lowlands or reservoirs without the use of collectors. This is often done with wells, allowing drainage water to be used for heat pump operation.

Useful video

You can install drainage for a shallow strip foundation by watching this video:

Step 1: Excavate	Dig a trench around the foundation, sloping away from the building.
Step 2: Lay Gravel Bed	Fill the trench with gravel to promote drainage.
Step 3: Install Perforated Pipe	Place a perforated pipe on the gravel bed to collect water.
Step 4: Cover with Fabric	Wrap the pipe in geotextile fabric to prevent clogging.
Step 5: Backfill with Gravel	Fill the trench with more gravel, covering the pipe.
Step 6: Final Backfill	Complete the trench with soil, ensuring proper slope away from the foundation.

If you have a shallow strip foundation, installing drainage is essential to the stability and longevity of your structure. You can avoid water buildup around the foundation, which over time could cause structural problems, by managing groundwater well.

First and foremost, a trench must be dug around the foundation’s perimeter, making sure the trench slopes away from the building. In order to avoid waterlogging, this slope helps divert water away from the foundation walls.

Subsequently, cover the trench with a geotextile fabric or permeable membrane to keep dirt and debris out of the drainage pipes. This process guarantees that the drainage system will always be effective and unobstructed.

Next, place perforated drainage pipes in the trench, making sure that the holes in the pipes face down. By gathering groundwater and directing it away from the foundation, these pipes will lessen hydrostatic pressure, which might otherwise compromise the stability of the building.

Fill the trench nearly to the top by covering the pipes with aggregate or coarse gravel. This layer supports and shields the drainage system while facilitating easy water flow into the pipes.

Lastly, add soil to the trench’s backfill, gently compacting it to ensure proper settling. To further encourage water to move away from the foundation, make sure the soil slopes away from the building.

By installing drainage for a shallow strip foundation according to these instructions, you can successfully shield your building from future water damage and keep its structural integrity for many years to come.

Video on the topic

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