Which foundation is better to build: strip or pile – design features and their comparison

When it comes to building a foundation for your home or any structure, choosing the right type is crucial. Two popular options are strip foundations and pile foundations. Each has its own design features and advantages, making the decision dependent on various factors, such as soil conditions, load requirements, and budget.

Many residential buildings choose to have strip foundations. They are made up of a continuous concrete strip supporting walls with weight on it. This kind of foundation is easy to build and is usually placed on solid, level ground. Many projects can afford to use it because of its simplicity, especially when building on relatively level ground.

Pile foundations, on the other hand, are made for more difficult circumstances. In order to reach stable soil or rock layers, they entail driving or drilling long columns, or piles, into the ground. In situations where a strip foundation might not be able to provide enough support, this kind of foundation is perfect for areas with weak or extremely compressible soil. Additionally, pile foundations can handle heavier loads and uneven terrain with greater adaptability.

A number of variables, including soil type, load-bearing capacity, cost, and construction time, must be taken into account when comparing these two foundation types. Although pile foundations provide more stability in difficult soil conditions, strip foundations are typically less expensive and simpler to construct. Determining whether a pile or strip foundation is the better option will require you to have a thorough understanding of the particular requirements of your project.

Foundation Type Design Features and Comparison
Strip Foundation Consists of a continuous strip of concrete; good for even, stable soils; suitable for lighter structures; more affordable and easier to build
Pile Foundation Uses long, slender columns driven deep into the ground; ideal for unstable or weak soils; can support heavier structures; typically more expensive and complex to construct

It’s important to know the main advantages and design elements of both strip and pile foundations before deciding which is best for your building project. Strip foundations, which are frequently found in residential construction, evenly distribute the load across the ground to provide sturdy support for lighter structures. Conversely, pile foundations transfer the building’s weight deep into the ground to more stable soil layers, making them perfect for larger, heavier structures or unstable soil conditions. This post will contrast these two foundation types to assist you in selecting the best option for your particular building requirements and site circumstances.

Pile foundation

This pattern looks like a lattice that has been put on pillars. All of the building’s principal points are supported by pillars that are joined by grillage. The locations with the highest loads and corners receive the most attention. Small buildings’ foundations mirror the design of the building; large structures opt for a sturdy foundation.

Concrete, reinforced concrete, metal, or wood can all be used as supports. The steel component is constructed like a cast pipe. Its screw variety has blades attached to it, which are used to screw the element into the ground.

Examining the welding points is essential when purchasing pillars. Bitumen mastic or other anti-corrosion materials need to be applied to the joint.

A grillage can be a metal beam or a slab or strip of reinforced concrete. The lower crown is known as the grillage when installing a log house. It lies atop mounting pads that are welded to mounds.

Foundation construction method

Piles are driven, inserted, or screwed into the ground, depending on the kind of material. Elements with a sharp tip and a blunt end are used in the latter scenario. The pillars are driven in using specialized machinery.

Wells are created and hollow pillars are inserted into them for a bored foundation. Concrete is poured into the base after reinforcement. Small holes are made for the screw supports, into which a drill bit or other specialized tool is used to screw them perpendicularly. They are strapped and leveled horizontally after installation.

Pros and cons of a pile foundation

Among the benefits are:

  1. Economy. The arrangement of a pile field will cost 30% less than a foundation strip.
  2. Resistance to climate change. This means that the installation of supports can be carried out in any season. In winter, the top layer of soil is heated to drill a hole.
  3. Long service life – up to 200 years.
  4. Possibility of erecting a structure on slopes and uneven areas. On a complex landscape with a slope of more than 15°, braces, spacers, and ties are additionally used.
  5. Suitability of the foundation for erecting buildings on a swamp or on loamy, clayey and peaty types of soil.
  6. Small volume of excavation work.
  7. High installation speed.

A pile foundation’s vulnerability to corrosion is a drawback. It will be challenging to rely on the stability of the structure when installing subpar components. Moreover, rocky soils cannot use it due to the nature of piles.

The layout of a ground floor or basement is limited by the technology used to build such a foundation. To insulate the empty space beneath the floor, more money will be needed. Concurrently, there are pile field projects for subterranean garage construction.

Strip foundation type

A strip foundation is placed around the whole perimeter of the future building and has the appearance of a solid reinforced concrete structure. It is utilized in the construction of both wooden and monolithic structures because of its great strength. A solid mass of reinforced concrete or interlocking building blocks makes up the foundation. A ceramic brick strip can be built on dry soils for constructing a barn or bathhouse.

Method of erecting a strip foundation

A significant amount of excavation work must be done before the foundation is laid. Initially, a 0.4 m-wide trench is excavated following the structure’s outline. The soil’s composition and the estimated load both have an impact on the pit’s size decision.

  1. Recessed strip foundation. It is installed below the level of soil freezing and is used on heaving soils, as well as when constructing concrete and brickwork.
  2. Shallow foundation. The design is used for SIP panels and panel buildings.
  3. Shallow strip, designed for log cabins and frame houses. This foundation is placed at a depth of 0.4-0.7 m. To protect against groundwater, drainage geotextile is laid in the trench and a sand and gravel "cushion" is poured. The density of each layer is at least 20 cm. If necessary, a leveling screed is installed.

Insulation and waterproofing materials are then installed. Depending on the circumstances of the construction, external waterproofing with an overlap on the walls is used. The strip is positioned beneath extruded polystyrene foam to counteract heaving forces.

The last steps involve pouring concrete mortar, installing a reinforcing belt, and mounting formwork. The final step needs to be finished in one sitting. If not, the foundation becomes less strong as butt joints form on the surface.

Pros and cons of strip foundation

Among its benefits are:

  • resistance to the negative impact of groundwater;
  • versatility;
  • reliability;
  • availability of self-assembly;
  • long service life;
  • possibility of arranging a basement or cellar.

Among the drawbacks, the following must be mentioned:

  1. High financial expenses. Premises under a common roof have different shrinkage, which can lead to the destruction of floors and roofing. The appearance of cracks can be prevented by constructing additional walls with expansion joints. This type of foundation is economically advantageous only on rocky soils and when it is necessary to arrange an underground floor.
  2. Labor intensity of work.
  3. Need for dismantling during repairs.
  4. Limited use on weak and uneven soils. The monolithic option is suitable for all types of soil except peatlands. Precast tape cannot be used for installation on slopes or in damp and heaving areas.

The particulars of your building project will determine whether you choose a pile foundation or a strip foundation. Strip foundations are a common option for a lot of residential buildings because of their affordability and simple design. They are a practical choice for many builders because they are easy to construct and perform well in areas with strong, stable soil.

On the other hand, when the load-bearing requirements are particularly high or the soil conditions are less stable, pile foundations become crucial. In order to give the structure a strong foundation, piles descend to more stable soil layers. They are therefore perfect for structures on slopes, high-rise buildings, and locations with expansive or soft soils.

Every kind of foundation has benefits of its own and works best in certain situations. In general, strip foundations are less expensive and easier to construct on stable ground for small to medium-sized projects. Even though they are more intricate and costly, pile foundations offer better support for heavier structures and in difficult soil conditions. You can choose the ideal type of foundation for your project by carefully weighing the soil’s properties, the weight of the building, and the overall design specifications.

The decision between strip and pile foundations ultimately boils down to how well site conditions, structural requirements, and cost are balanced. A structural engineer’s advice can help you choose the best foundation for your particular circumstances, ensuring the durability and security of your building.

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Andrey Ivanov

Experienced civil engineer with more than 20 years of experience. Specializing in the construction of industrial and civil facilities. Author of many publications in professional journals.

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