PILED RAFT FOUNDATIONS

A Piled raft is the superior choice for a foundation on projects requiring piles. This method allows for construction directly on the slab, with floor finishing placed on top with ease. Our piled raft foundations offer a streamlined solution for your construction project, saving time and money. Unlike traditional strip foundations or pile and beam systems, our piled raft design provides flexible options and efficient load distribution, making it a versatile choice for all construction types.

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Piled Raft Foundation Contractors

What is a Piled Raft Foundation?

A piled raft foundation is a combination of a pile foundation and a raft foundation. It is constructed by first installing piles, and then placing a raft foundation that connects all the piles. Let's break it down by first understanding what Piles are. Vertical structural elements are driven into the ground to transfer loads from the superstructure to stable soil or rock layers when the upper soil is weak or compressible.

Raft foundations are commonly used in areas with weak soil, such as soft clay or sand, where other foundation types may not be suitable. These foundations float on the soil, making them a practical option in challenging ground conditions.

The key factor in designing a piled raft foundation is the interaction between the piles, the soil, and the raft. The raft is a suspended slab that transfers the structure's lateral and axial loads to the piles, which then carry the loads through shaft friction and end bearing.

A raft foundation is a thick, reinforced concrete slab supported by a grid of steel bars. This design helps prevent the foundation from bending, breaking, or sinking under the weight of the building. The weight of the structure and the characteristics of the underlying soil determine the thickness and depth of the raft foundation.

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We achieve cost-effective foundations while prioritizing safety and reducing your site's environmental impact. Our innovative approach combines speed and sustainability, ensuring your project meets the highest standards.

WHEN TO USE PILED RAFT FOUNDATIONS

Raft foundations were historically used for commercial buildings like warehouses and supermarkets. In recent decades, they have become increasingly popular for domestic projects such as extensions and conservatories. 

Raft foundations suit buildings with relatively small footprints and modest structural loads. They are also a good option for basement constructions where the foundation slab can support live loads. Additionally, raft foundations can be an excellent solution for sites with poor soil conditions or limited access to large excavation equipment.

Raft foundations' key advantages are their simplicity and cost-effectiveness, making them a viable choice for a range of construction projects, from commercial to domestic.

When ground conditions make traditional shallow foundations unfeasible, a piled raft foundation can be cost-effective. Suspended raft foundations are reinforced concrete slabs, typically 225-300mm thick, designed to cover the entire building footprint, including supporting external structures like balconies. Our design team provides efficient, integrated solutions to address site constraints such as existing services, underground structures, sloped terrain, and tree root protection zones.

RAFT FOUNDATION TYPES

Raft foundations come in various forms, but the principal options are:

Solid Slab Raft Foundation: This is the most prevalent type, comprising a single reinforced concrete slab serving the entire foundation.

Slab-Beam Raft Foundation: This design incorporates beams and thick edges, enhancing structural integrity.

Cellular Raft Foundation: This variation features spaces (cells) within the slab, resulting in a lighter overall foundation.

Piled Raft Foundation: This approach utilizes deep-driven piles to offer additional support, making it suitable for sites with poor soil conditions.

The choice of raft foundation depends on factors such as the building's weight, the soil conditions, and the project's specific requirements. A structural engineer's expertise is essential in determining the optimal foundation type for any given construction endeavor.

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A Fast and Cost-effective Solution for Foundations
Why Choose Quickdeck?

Quickdeck is our foundation and ground floor system specially designed for residential and commercial structures. Our solution provides cost and schedule certainty for private and commercial projects while being safer and more environmentally friendly than other methods. With Quickdeck, you can trust in a foundation that will support your project with unwavering strength and efficiency.

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Quicker

Quickdeck is significantly faster than traditional methods, delivering a remarkable 70-80% increase in efficiency. This innovative approach offers unparalleled program certainty, ensuring reliability and predictability that surpasses conventional construction techniques.

Safer

Quickdeck delivers a safer and more secure environment on-site. It comes with LABC and NHBC approval, ensuring unparalleled quality and compliance. Our solution is the clear choice for those seeking a reliable and secure solution for their construction projects.

Cost

By streamlining the program and eliminating traditional elements like excavation for ground beams and the need for a piling mat, our Quickdeck solution can achieve improved cost certainty for your project.

Less Environmental Impact

Quickdeck is an eco-friendly solution that reduces the carbon footprint of construction sites. in the UK. It uses less concrete, generates less waste, and requires fewer vehicle and machinery movements, making it a more sustainable option.

See how our Quickdeck solution can bring value to your construction projects.

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Advantages of Piled Raft Foundations

Raft foundations are the superior choice for buildings, offering numerous benefits that make them the preferred option for architects and builders alike. They are particularly well-suited for areas with poor soil conditions, such as soft clay or loose sand, where other shallow foundation types often fail to perform adequately.

Raft foundations offer superior stiffness, allowing for greater settlement values than isolated footings, typically double, without compromising structural integrity. Furthermore, raft foundations significantly reduce differential settlements, ensuring the stability of the entire structure.

The key advantage of raft foundations is their ability to distribute a building's weight evenly across a large surface area, effectively preventing the structure from sinking or shifting. This makes them an ideal solution for sites with challenging soil properties.

Furthermore, raft foundations are often more cost-effective than deep foundation systems, such as pile foundations, as they require less extensive excavation and can serve as the building's floor slab. This streamlined approach reduces both time and expense in the construction process.

The versatility of raft foundations is a key advantage, as they can be precisely tailored to the specific soil conditions and the engineer's design preferences. Designers should confidently embrace raft foundations as a robust and adaptable foundation system capable of overcoming the limitations of poor soil conditions.

In summary, raft foundations are the clear choice for constructing stable and reliable buildings, particularly in unfavorable soil conditions. Their superior performance and cost-effectiveness make them the preferred foundation solution for today's architects and builders.

Piled Raft Foundation Contractors

The foundation's role is to support structures, thereby transferring their load to soil or rock layers with sufficient bearing capacity and optimum settlement characteristics. There are two main types of foundations: shallow foundations and deep foundations. The shallow foundations are primarily used when the loads imposed by a structure are relatively low compared to the bearing capacity of the surface soils. Deep foundations on the other hand are needed where the bearing capacity of the surface soils is not adequate to support the loads imposed by a structure, therefore these loads need to be transferred to deeper layers with high bearing capacity.

Raft foundations, also known as mat foundations, are shallow foundations consisting of a reinforced concrete slab of uniform thickness (typically 150-300 mm) covering the entire footprint of a building. This slab spreads the load from columns or walls over the foundation area, effectively "floating" on the ground. When standard raft foundations are insufficient, they can be reinforced with piles to create a more robust pile foundation.

Piles are unequivocally defined as deep foundations composed of long, slender, columnar elements typically constructed from steel or reinforced concrete. A foundation is categorically considered 'piled' when its depth exceeds three times its breadth (Atkinson, 2007). Pile foundations essentially transfer loads through soft, compressible strata or water to robust, compact, less compressible, and sturdier soil or rock at considerable depths.

Adding piles to a raft significantly enhances the foundation's size and ability to withstand horizontal loads. This enhancement results in a substantial reduction in settlement and differential settlement and an overall improvement in the foundation's load capacity.

Piled raft foundations are commonly used for large structures when soil conditions may cause excessive settlement. They are especially popular for high-rise buildings. The design process involves determining the optimal number, position, diameter, reinforcement, and length of piles to ensure structural stability and cost-effectiveness. Piles provide stiffness, while the raft provides additional capacity, working together to prevent excessive settlement.

In an Unconnected Piled Raft Foundation (UCPRF), piles are not directly connected to the raft. Instead, they are separated by a cushion of structural fill, which helps redistribute loads between the raft and piles. This can be a cost-effective solution that still maintains performance.

FAQ

How Thick is a Piled Raft Foundation?

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Piled Raft foundations, also known as raft footings or mat foundations, consist of reinforced concrete slabs with a consistent thickness (usually between 150 mm and 300 mm) that span a large area, often encompassing the entire building footprint.

What is the biggest benefit of using a Piled Raft Foundation?

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The primary purpose of a piled raft foundation is to evenly distribute the load of the building over the entire available surface area. This effectively minimizes stress on the ground below, creating a stable foundation that can withstand ground movement without compromising structural stability.

Do you need Planning Permission for Piling?

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Under the Town and Country Planning Act of 1990, planning permission is mandatory for any development activities such as building, engineering, mining, or manufacturing new materials on land.

What are the three types of Raft Foundation?

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There are four definitive types of raft foundation: solid slab rafts, slab beam rafts, cellular rafts, and piled rafts.

Do Raft Foundation require deeper excavation?

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Piled Raft foundations are the superior choice due to their speed and cost-effectiveness. They eliminate the need for deep excavations and reduce material usage by combining the foundation with the ground slab. Choose raft foundations for a quick and efficient building solution.

How do you strengthen a Piled Raft Foundation?

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To strengthen a piled raft foundation, increase the thickness of concrete in high-load areas like under columns and implement a system of main and secondary beams. Solid raft foundations are ideal for quick and easy construction, as long as a suitable stratum is present within 3 meters of the site level.

What is the difference between Raft Footing and Raft Foundation?

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Raft foundations excel in distributing load evenly over a large area, making them ideal for poor soil conditions or high water tables. On the other hand, spread footings are preferred in stable soil conditions for their ability to concentrate load at specific points.

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Cost-effective

The QuickDeck solution offers our clients greater financial certainty by significantly reducing the time required to construct a house. This is achieved by eliminating the need for extensive excavation to create ground beams and a piling mat.

Safer, Cleaner and Greener

QuickDeck offers a variety of advantageous features that notably enhance site safety and the overall working environment. Our method utilizes significantly less concrete than conventional two-stage Foundations and generates a reduced amount of spoil removal. These factors alone greatly minimize the requirement for heavy machinery – consequently leading to a substantial decrease in carbon emissions and a significantly lower carbon footprint.

It take less time

Our QuickDeck solution has been found to be up to 70% faster than the conventional two-stage foundation method. This leads to significant cost savings on construction schedules for our clients.

Testimonials

They were perfect right from the survey stage till the completion. The work was carried out smoothly without any hindrances and we were able to meet the deadlines,

Sharon Saggu - Project Manager

Piled Raft Foundations has been our go-to company for over a decade. Efficient and very professional, and always have the technical knowledge to get the job done on time and with our stipulated budget.

Roger Schmidt - Chartered Surveyor

We are a development construction company and we required a specialist piling company to work with, to take all the stress-off us. PRF did just that, they were professional and polite to deal with and understood the project well.. Will recommend them to anyone looking for a genuine, reliable dilapidations company.

Aamir Sadiq - Manager

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