When a Building Owner plans to carry out construction work near or on a party wall, the Party Wall etc. Act 1996 comes into play. This piece of legislation is designed to protect both the Building Owner and the Adjoining Owner (neighbour) from the impact of such work. Below is an overview of the key issues, solutions, and requirements for any building work near a boundary line.
Why Does the Party Wall Act Matter?
The Party Wall Act 1996 applies when construction is planned on or near a party wall or boundary line. It protects both the party carrying out the work (Building Owner) and the neighbour whose property might be affected (Adjoining Owner). Whether it’s a new extension, changes to foundations, or even the trimming of roof eaves, these works can have significant implications for both properties.
Potential Issues with Building Near a Boundary
One common scenario is when a neighbour plans to build near the boundary, but the existing wall foundation slightly encroaches onto the neighbouring land. If the new wall’s foundation clashes with the neighbour’s foundation, it could lead to structural instability or even undermine the integrity of the Adjoining Owner’s property.
- Existing Foundations: Older foundations are typically concentrically loaded, meaning the weight from the building is distributed evenly. However, when a new wall is added next to this, it could alter how the forces are transferred, leading to ‘eccentric loading,’ which places uneven stress on the foundation and surrounding soil.
- Impact on the Adjoining Owner’s Property: If the new foundation extends too close to the neighbour’s, it could destabilise their existing foundation, increasing pressure on the soil beneath and possibly causing movement in their property.
Solutions to Foundation Clashes
Several solutions can address the issue of building next to a boundary without destabilising the neighbour’s property:
- Underpinning:
- What is Underpinning? Underpinning is a method used to extend or reinforce an existing foundation to prevent movement or settlement. If the new wall’s foundation interferes with the neighbour’s, underpinning is often the go-to solution.
- How Does It Work? The process involves excavating around the existing foundation and then extending it with a concrete ‘toe’ that bridges across to the Building Owner’s side. This creates a larger, concentrically loaded foundation that distributes the weight evenly.
- Cantilevered Slab Foundations:
- What is a Cantilevered Slab? This type of foundation transfers the load of the new wall to the soil without directly interfering with the neighbouring foundation. It is designed to avoid the need for underpinning.
- How Does It Work? The cantilevered slab extends away from the neighbour’s foundation, with the new wall sitting on the edge of this slab. This design requires steel reinforcement to ensure the foundation is stable.
- Advantages: The cantilevered slab avoids the need for underpinning, which can be expensive and time-consuming. It also minimises the potential disruption to the neighbour’s property.
- Trimming the Neighbour’s Foundation:
- In some cases, it may be possible to carefully trim back the neighbour’s foundation where it projects over the boundary. However, this approach depends on factors such as the load carried by the foundation and the soil conditions.
- Limitations: If the load tests show that trimming is not feasible, underpinning may still be necessary.
Legal Rights Under the Party Wall Act
The Party Wall Act 1996 provides legal provisions that allow the Building Owner to trim or remove the projecting part of the Adjoining Owner’s foundation, but only if it does not destabilise the existing structure. It’s crucial that the work is carried out carefully, with full consultation with the Adjoining Owner and their Party Wall Surveyor.
Overhanging Roofs and Other Non-Structural Elements
If the Adjoining Owner’s roof overhangs the boundary, the Building Owner has the legal right to trim or cut back these elements to accommodate the new wall. However, there are some important considerations:
- Weatherproofing: Any gaps left between the two walls should be carefully managed to avoid issues like dampness, debris buildup, or even pest infestation.
- Rainwater Goods: Gutter, fascia, and soffit boards should be moved or adjusted to redirect water away from the construction site. The design should ensure that water runoff does not affect the neighbour’s property.
The Role of the Party Wall Surveyor
The Party Wall Surveyor’s role is to ensure that both parties comply with the Act and that the work is carried out safely and fairly. They are involved in:
- Notices: The Building Owner must serve Party Wall Notices in good time before work begins. These notices inform the Adjoining Owner of the proposed works and give them the opportunity to respond.
- Agreements (Awards): If there are disputes or concerns, a Party Wall Surveyor can help mediate and establish an agreement between the two parties (known as an Award). This will outline how the work should be carried out and include protections for both sides.
Construction Process and Potential Issues
When work is underway, there are several other considerations:
- Mortar Droppings: As the new wall is built, mortar or debris may fall into the gap between the two properties, which could create maintenance issues later on.
- Structural Monitoring: Depending on the scale of the work, it may be necessary to monitor any movement in both properties. This can be done through visual inspections or using monitoring equipment like ‘tell-tales’ or dynamic sensors.
Other Considerations
- Cost: The Building Owner is typically responsible for the costs associated with the Party Wall work, including any underpinning or additional foundation work. The overall cost and time for construction may influence which solution (underpinning vs. cantilever slab) is selected.
- Disruption: If the work involves significant structural changes, such as underpinning or cutting back foundations, it could cause disruption to the Adjoining Owner. Discussions about working hours, noise, and access should be included in the Party Wall Award.
Final Thoughts
When building near or on a party wall, careful planning and consultation with a Party Wall Surveyor are essential. Whether it’s for a new extension or other structural works, ensuring that the neighbour’s property remains safe and unaffected by the work is a legal requirement under the Party Wall Act 1996. Choosing the right foundation solution, whether underpinning or a cantilevered slab, and managing any overhanging structural elements can avoid future disputes and ensure both parties are protected.
Before starting your project, ensure that you’ve served all necessary Party Wall Notices and obtained the appropriate consents. This will help avoid legal issues down the line and ensure a smoother construction process.
If you’re unsure of your rights or obligations under the Act, it’s always a good idea to consult with a Party Wall Surveyor.