03 Aug Why Piling May Be Needed When Adding Another Storey
Adding another storey to your property can be an effective way to create more living space without reducing the size of your garden or moving to a larger home. It could provide room for additional bedrooms, a home office, a bathroom or an entirely new living area.
However, building upwards changes more than the appearance and layout of a property. It also increases the amount of weight that must be safely supported by the existing structure and foundations.
In some cases, the original foundations will be able to accommodate the additional load. In others, they may need to be strengthened or supplemented with piling before construction can begin.
Why More Homeowners Are Considering Building Upwards
Extensions, loft conversions and other householder developments remain a popular way of improving residential properties.
Between October to December 2025, planning authorities in England made 154,500 decisions on householder development applications, including applications for extensions, loft conversions and conservatories.
Creating additional usable space may also increase a property’s appeal and value. Nationwide’s 2025 analysis found that an extension or loft conversion incorporating an additional bedroom could increase a home’s value by as much as 24%, although the result will always depend on the property, location, design and quality of the completed work.
Building upwards can therefore be an attractive option, but the structural suitability of the property must always be established before plans progress too far.
What Happens to the Foundations When Another Storey Is Added?
Every building transfers its weight through its walls, columns and floors into the foundations and then into the ground below.
Adding another storey increases this load. New walls, floors, roofing, insulation, finishes, furniture and occupants all add weight that the existing building may not originally have been designed to carry.
This is particularly relevant for older properties. Although many older homes remain strong and stable, their foundations can vary considerably in depth, width, condition and construction.
The fact that a property has performed well for many years does not automatically mean that its foundations have enough spare capacity for another storey.
When Might Piling Be Required?
Piling will not be required for every upward extension. The need for it should be determined by a structural engineer following an assessment of the building, its foundations and the surrounding ground conditions.
Piling may be recommended where:
- The existing foundations are too shallow or narrow to support the increased load
- The ground close to the surface is weak, variable or unsuitable
- The property is built on shrinkable clay or ground affected by nearby trees
- There is a history of settlement, subsidence or structural movement
- The proposed design creates concentrated loads in particular areas
- Previous alterations have changed how loads are transferred through the building
- Traditional foundation strengthening would require excessive excavation
- Access limitations make other foundation methods impractical
A combination of these factors may also be present. Every property and proposed extension must therefore be considered individually.
How Does Piling Support an Additional Storey?
Piles are structural elements installed deep into the ground. Once installed, the piles can be connected using reinforced concrete ground beams, pile caps or a raft. This creates a foundation system capable of receiving and distributing the additional structural loads.
Depending on the property and site conditions, mini-piling may be suitable. Smaller piling rigs can operate in restricted areas where access through a side passage, doorway, garage or existing building may be limited.
What Should Be Checked Before Construction Begins?
Before adding another storey, the project team will usually need to establish exactly how the existing building is constructed and how the proposed work will affect it.
This process may include:
- A measured survey of the property
- An inspection by a structural engineer
- Trial pits to confirm the size, depth and condition of existing foundations
- A ground investigation or review of local ground conditions
- Structural calculations for the proposed additional load
- An assessment of walls, floors, beams and roof structures
- Consideration of neighbouring buildings and party wall requirements
- A review of access for piling equipment and materials
Completing these investigations early can help identify potential foundation requirements before the main building work begins. It also allows the piling and structural solution to be designed around the property rather than treated as an unexpected addition later in the project.
Planning Permission and Building Regulations
In England, certain qualifying houses may be able to add one or two storeys under permitted development rights, subject to restrictions, height limits and prior approval. Other properties will require a full planning application.
Permitted development rights do not remove the need to comply with Building Regulations or other requirements, such as the Party Wall etc. Act where applicable.
It is therefore important to seek advice from the relevant professionals and your local planning authority before beginning work.
Build Upwards on the Right Foundations
Adding another storey can transform a property, creating valuable additional space and allowing the building to meet the changing needs of its occupants.
The success of the project, however, depends on more than the new rooms above ground. The existing structure and foundations must be capable of safely carrying the additional load.
Where the original foundations are unsuitable, piling can provide a strong, carefully engineered solution by transferring the new loads into more reliable ground.
How We Can Support Your Project
At Underpin & Makegood, we have decades of experience delivering specialist foundation, piling and structural solutions for residential and commercial properties.
If you are considering adding another storey, our team can review the proposed project and help determine an appropriate foundation solution. We can work alongside your structural engineer, architect, builder and Building Control team to ensure the piling works are properly designed and coordinated.
Our piling services include:
- Sectional auger mini-piles
- Grout-injected continuous flight auger piles
- Steel-cased bottom-driven piles
- Steel-cased Grundomat-driven piles
- Reinforced concrete ground beams, pile caps and foundation systems
- Restricted-access and open-site piling
- Complete design-and-build piling solutions
All piling work is undertaken by trained and experienced team members, with solutions available for a wide range of ground conditions and access requirements. Our piling work is also covered by a ten-year Defects Insurance Guarantee.
Our focus is on providing clear advice, reliable communication and a high-quality service throughout every stage of the project.
If you are planning to add another storey and would like advice about piling or foundation strengthening, contact U&M Group today.