Understanding when sectional hit-and-miss foundation bays are required can be confusing. This is particularly true where proposed works have the potential to affect neighbouring foundations and require additional safeguards to minimise the risk of damage, movement, and disputes between owners.
As a team of experienced Party Wall Surveyors, we help building and adjoining owners navigate all practical and legal matters relating to sectional hit-and-miss foundation bays.
In this guide, we’ll explain what sectional hit-and-miss foundation bays are, when they’re required, and the practical and legal considerations involved in their use.
What are Sectional Hit-and-Miss Foundation Bays?
Sectional hit-and-miss foundation bays are a construction method of excavating foundations into smaller sections. This involves digging part of a foundation trench, filling it with concrete, letting the concrete set, and repeating the process until the foundations are complete.
This type of construction process is usually required when the proposed foundations border or adjoin an existing neighbouring structure, therefore requiring additional safeguards and protective measures throughout the excavation.
In simple terms, sectional hit-and-miss foundation bays help neighbouring structures retain adequate support throughout the excavation process. By only opening small sections of the trench at any one time, the risk of movement or structural damage is significantly reduced.
When are Sectional Hit-and-Miss Foundation Bays Required?
Sectional hit-and-miss foundation bays are often required when proposed excavation works pose a significant risk of moving, damaging, or compromising a neighbouring structure.
This is necessary in cases where excavating the entire trench at once could remove substantial ground support for the neighbouring structure, increasing the likelihood of movement or structural damage. In these situations, excavating the trench into smaller sections allows support for the neighbouring structure to be maintained throughout the process, significantly reducing any risks.
In many cases, the only open section of excavation at any one time will be a small, controlled trench, often in the region of 1m–1.5m in length, helping to minimise the impact on neighbouring foundations.
This type of excavation is typically slower than undertaking foundations in a conventional strip fashion. Therefore, it’s best to discuss proposals with a contractor at the earliest possible date to ensure work can be completed within the designated time frame.
Works involving hit-and-miss foundation bays may fall within the scope of the Party Wall etc. Act 1996. Where excavations are taking place within the distances specified in Section 6 of the Act, a building owner may be required to serve a Party Wall Notice before proceeding.
The purpose of the Party Wall procedure is to ensure safeguards are in place before works begin, helping reduce the risk of damage to neighbouring structures and providing a legal framework for resolving any disputes that may arise.
What is Hit-and-Miss Underpinning?
Hit-and-miss underpinning is a closely related construction technique used when strengthening or deepening existing foundations.
While sectional hit-and-miss foundation bays are often associated with new foundations, underpinning generally refers to existing foundations that require repair, strengthening, or additional support.
The same principle for hit-and-miss foundation bays applies to underpinning, with the controlled excavation of segmented sections helping to reduce the risk of impacting a neighbouring structure.
Where underpinning works have the potential to affect adjoining properties, the Party Wall Act may also apply. As with sectional hit-and-miss foundation bays, the purpose of the Act is to establish appropriate risk management and dispute resolution measures before works begin.
Common Risks of Hit-and-Miss Foundation Works
Although hit-and-miss foundation bays are specifically designed to minimise risk, excavation works near neighbouring properties still require careful planning and supervision.
Potential risks can include:
- Structural movement.
- Settlement or subsidence.
- Cracking of walls and other building elements.
- Ground instability.
- Damage to neighbouring structures.
Party Wall procedures, and ultimately the agreement of a Party Wall Award, can introduce a number of protective provisions to reduce the risk and effect of the building owner’s proposed works on surrounding structures.
Why Choose Stokemont for Sectional Hit-and-Miss Foundation Bays and Other Party Wall Matters?
If you’re planning foundation bay work that may affect a neighbouring structure, seeking advice from qualified Party Wall Specialists like Stokemont can help ensure correct procedures are followed from the outset.
Our experienced Party Wall Surveyors advise building owners and adjoining owners on excavation works and all matters relating to the Party Wall etc. Act 1996. Whether you’re planning a new extension, basement excavation, or other works close to neighbouring foundations, we can help ensure appropriate safeguards are in place and any potential disputes are managed effectively.
If you’d like clear and practical advice on a proposed foundation bay or any other Party Wall matter, contact our surveyors today.
FAQs
They can be. Where excavation works are taking place within the distances outlined under Section 6 of the Party Wall etc. Act 1996, a building owner may be required to serve a Party Wall Notice and follow the relevant Party Wall procedures before work can begin.
If an adjoining owner dissents to a Party Wall Notice relating to hit-and-miss foundation bay works, this does not automatically prevent the work from proceeding. At this point, it would become a dispute under the Party Wall etc. Act 1996, and one or two surveyors would need to be appointed. This will depend on whether the parties agree to use a single agreed surveyor or appoint their own surveyors.
The surveyor(s) will review the proposed works, assess the risks to neighbouring structures, and determine what safeguards are necessary before construction can begin. Depending on the nature of the work, this may include provisions on:
- Working methods (e.g., designated or prohibited tools and construction methods).
- Access arrangements.
- Working hours (e.g., no work before or after a certain time or on weekends).
All agreed measures are designed to protect the adjoining property during the proposed excavation works while enabling the building owner to proceed with the project safely and responsibly.
