The inclusion of deleterious or prohibited material clauses for building contracts and professional appointment documents is common throughout the construction industry. While it is thought that these types of clauses will differ slightly from contract to contract, the common intention behind all of them is to prohibit the use of unsuitable or dangerous materials during construction projects.

Partner at Rosling King LLP, Jonathan Hyndman has been exploring the central legal issues that construction contract parties must consider when negotiating what provisions are being made for prohibited materials. Deleterious material is defined as those which are capable of causing damage or harm to an individual, the environment or to buildings and infrastructure. While there is legislation in place to limit or prevent the use of known hazardous materials, it is inevitable that is legislation will require addition as more deleterious materials are identified. In some cases, when the material is used, it is not known to be problematic and it is only later that more harmful effects become known to us. An example of this is the fatal use of asbestos in building projects and the use of polyethylene cores in cladding products.

Concern over a material’s suitability or reliability can also be cause to warrant its prohibition on a project. Therefore, it is vital that developers, consultants and contractors consider the specific circumstances of the individual project while exploring and negotiating the scope of the obligation not to specify or use prohibited materials.

When it comes to the law it is vital that, when negotiating a contract, the extent of the definition of prohibited materials in the construction contract is considered. At the moment there is no standardised industry form and contracting parties are free to be as broad or as narrow as they see fit when drawing up a contract, with due regard to the nature and circumstances of the project.