Balustrade Design Responsibilities and Liabilities for Garden Designers
One of the most frequently posed questions from garden designers concerns liability and responsibility for the design of safety rails, especially balustrades to the outer edges of a raised platform, mezzanine, decking or paved terrace with a potential hazard of injury by falling.
Liability may arise under Contract Law and The Consumer Rights Act 2015, (CRA) which mandates that goods must be of a satisfactory quality, and fit for purpose. This is a powerful catch-all, as it may be widely defined, to incorporate sound design and may include negligence on the part of the specifier unless robust logic is applied. Design liability falls under building compliances in particular, although any complaint or dispute would likely fall under the CRA.
Designers should be aware that any change of level greater than 600mm requires a safety barrier to be designed into a proposed scheme, which usually takes the physical form of a fixed balustrade.
Commonly used Balustrade Materials
Most modern designs favour timber or metal barriers as opposed to traditional stone piers and balusters, with base and capping rails constructed in stone or molded concrete such as found in stately homes, especially due to cost factors.
Stainless-steel wire (marine grade) to AISI 316 is recommended for use as cabling.
Timber decking projects may be designed with integrated horizontal and vertical elements combined into a semi-monolithic structure, incorporating balustrades built to meet the same criteria as metal barriers.
Toughened glass barrier, with suitable metal uprights built into the foundations of a raised patio area are other options, especially for modern design residences.
Specification
Regulations concerning balustrades may be found under the Building Regulations Approved Document Part K, (Protection from Falling) BS 6180:2011 design and safety guidelines, which covers collision and impact factors.
Balustrades are mandatory for all changes of level greater than 600mm as described above, with a minimum height (recommended) of 1100mm for external projects (900mm for internal). Maximum permitted gap between cables should not allow for the passage of a sphere greater than 100mm when under pressure to prevent small children from becoming trapped.
If small children have access to the site, cables should be installed vertically, not horizontally, as they may be used as a ladder, posing a risk of falling. The same maximum gaps apply.
The balustrade must provide sufficient structural integrity (sideways collision) or load bearing and material selection to withstand a breaking load of 9.5kN, and the methods of fixing the material to the base is a critical factor in achieving a robust barrier.
Writing a specification for safety balustrades may not fall within the comfort zone of garden designers, and it is often preferable to include a statement on any drawings or plans to the effect that ‘Balustrade design by a specialist contractor’ may be an option.
A great deal will depend on the site, and proposed use. A family with small children, or a wish to hold frequent large outdoors barbecues and parties, where the risk of collision and load bearing pressure may be extreme, should consider engaging a specialist contractor to propose and design a site-specific solution to this important safety feature.
