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Does Functional Dependence on a Party Wall Trigger Section 11(11) of the Party Wall Act?
Tuesday 3rd June 2025
One of the more nuanced aspects of the Party Wall etc. Act 1996 lies in interpreting the phrase “making use” of a party wall, especially under Section 11(11). This provision comes into play when a Building Owner appears to benefit from a wall originally constructed at the sole expense of the Adjoining Owner. But what exactly does “making use” mean in practice?
Does it require a physical tie-in to the wall? Or can it also apply to situations where a new structure relies on the presence of the party wall — without ever physically touching it?
A Common Scenario in Practice
Recently, we encountered a real-world example that illustrates the issue. A Building Owner constructed a single-skin blockwork wall adjacent to an existing party wall. Importantly, the new wall was not structurally fixed to the party wall. There were no mechanical ties, no flashing, no cutting-in — nothing that would suggest physical integration.
However, it was also clear that the new construction was significantly reliant on the party wall in functional terms. Without the party wall acting as a shield, the new wall would not have complied with current Building Regulations for structure or thermal performance. Moreover, the wall was clearly not designed to withstand weather exposure on its own. It derived direct benefit from the presence of the party wall, even if no fixings or structural ties were used.
This raises the key legal question: Is this functional dependence sufficient to trigger Section 11(11)?
Understanding Section 11(11)
Section 11(11) of the Party Wall etc. Act 1996 states that where a Building Owner “makes use” of an existing party wall or structure that was wholly built by the Adjoining Owner, they must pay a “due proportion” of the cost of its construction.
Crucially, the Act does not define what it means to “make use” of the wall. As a result, this phrase has become a point of debate and interpretation — one that surveyors, lawyers, and property owners continue to navigate in practice.
Is Physical Connection Required?
It’s often assumed that unless you physically connect to the party wall — for instance, by cutting into it, tying in, or placing loads on it — you haven’t “made use” of it. But this view may be too narrow. A growing body of professional opinion holds that a wall can be used in more subtle but equally significant ways.
If a new structure depends on the party wall for environmental shielding, thermal compliance, structural benefit, or even planning viability, it may still fall under the scope of Section 11(11). The test isn’t just whether there’s a bolt or tie. It’s whether the wall would function as intended — or comply with regulations — in the absence of the adjoining party wall.
Professional Commentary and Interpretation
There is limited case law under the 1996 Act on this precise point. However, legal commentary and earlier cases such as Rees v Williams [1973] support a broad reading of the concept of “use.” In that case, the courts acknowledged that benefiting from another’s construction — even without direct physical connection — could give rise to compensation.
Leading authorities in party wall matters, including Nicholas Isaac KC and John Anstey, have argued that “use” should be interpreted to include any substantial benefit derived from the party wall. This may include weatherproofing, regulatory compliance, or structural efficiency.
In practice, experienced Party Wall Surveyors often assess three key questions when determining whether Section 11(11) is triggered:
First, would the new wall function properly, or meet Building Regulations, without the adjacent party wall?
Second, does the new wall clearly rely on the party wall for part of its design purpose, such as thermal shielding or lateral support?
Third, would the new wall be compromised — practically or legally — if the party wall were removed?
If the answer to any of these questions is yes, then a good argument can be made that the Building Owner is indeed “making use” of the party wall.
Conclusion
Physical attachment is not a strict requirement under Section 11(11). A Building Owner may be considered to have made use of a party wall if their construction derives clear functional or regulatory benefit from its presence — even if there is no visible or mechanical connection.
In such cases, a Party Wall Surveyor can determine what proportion of the original cost should be reimbursed, and formalise this through a Party Wall Award. While this area of the law remains somewhat grey due to the absence of definitive case law, a pragmatic, benefit-based interpretation is gaining traction among professionals.
Need Expert Advice on Party Wall Disputes?
If you're facing a situation where Section 11(11) may apply — or if you’re unsure whether a neighbouring construction project is using your wall without fair contribution — our team can help. We provide specialist advice, detailed assessments, and formal Party Wall Awards that stand up to legal scrutiny.
Contact us today to speak with an experienced Party Wall Surveyor or to arrange a consultation.
