When Half Measures Go Too Far: How to Rectify Unauthorised Party Wall Works
posted 18th August 2025
At Tayross Associates Ltd, we are frequently appointed to advise on complex party wall disputes and irregularities. One recurring issue involves unlawful modifications to party walls—specifically, where a Building Owner raises an existing wall by only half its thickness, without proper notice or consent. Despite the technical nature of these disputes, the implications are significant both legally and financially.
Understanding the Issue
In a recent case, a Building Owner raised an existing party wall, but only to half the required thickness. This partial construction:
i. Deviated from the agreed Party Wall Award, and
ii. Was not properly notified under the Party Wall etc. Act 1996.
This renders the works unauthorised.
The Party Wall Act provides a clear statutory framework. Where a party wall already exists, the Building Owner may raise it to the necessary height across its full thickness, provided they serve a valid party structure notice under section 3 and obtain a new Award under section 10. Importantly, while Adjoining Owner consent is not needed for section 2 works, the proper procedural steps must still be followed.
Surveyors are often asked whether unauthorised works can be retrospectively approved. The short answer is no—we cannot retrospectively legitimise unlawful construction. However, we can determine a way forward.
Recommended Immediate Actions
If you’re a Building Owner or advising one, here’s what should happen next:
i. Cease all ongoing works to avoid compounding the issue.
ii. Record the facts: Take measurements, photographs, and compare with the original Award drawings.
iii. Notify both parties that the current works fall outside the scope of the Award and are unauthorised.
How to Regularise the Works (Without Adjoining Owner Consent)
To bring the works back within the lawful remit of the Party Wall Act:
1. Serve a new section 3 notice to the Adjoining Owner, clearly describing the intended works:
“Raise the existing party wall to the required height across its full thickness, including all necessary cutting in, toothing, bonding, weathering, and incidental works under s.2(2)(a), (f), (n).”
2. Agree a new Award under section 10, which should address:
a. The methodology: sequencing, structural integrity, weatherproofing, and fire stopping.
b. Rectification of existing works: either full removal or adaptation so the wall becomes a complete, bonded structure of full thickness.
c. Access rights (s.8), updated Schedule of Condition, and any temporary protections.
d. Compensation for damage (s.7(2)) and reasonable provisions for costs.
3. The Building Owner bears all associated costs, including surveyors’ fees, any necessary reconstruction, and making good.
What Happens If the Issue Isn’t Addressed?
Failure to regularise can expose the Building Owner—and potentially the appointed surveyors—to:
i. Injunctions or legal action for trespass and nuisance.
ii. Costly damages and reputational harm.
iii. Professional risk, especially if surveyors are seen to have tacitly approved or ignored unauthorised works.
Conclusion
This case is a cautionary tale: even seemingly minor deviations from a Party Wall Award can have serious legal and professional consequences. At Tayross Associates Ltd, our experienced team of chartered building surveyors ensures that works remain compliant with the Party Wall Act at every stage.
If you’re unsure whether your project complies—or if you need to regularise past works—get in touch with us today for expert advice and support.
