DESIGN WORK BY PLUMBING SUBCONTRACTORS - WHAT TO BE AWARE OF
Plumbing subcontractors often engage in a certain amount of design work, whether or not the subcontract specifically refers to that being part of the scope of works. There are various matters to consider and be aware of when it comes to undertaking design work.
Commercial projects
In commercial projects, particularly larger commercial projects, it is often the case that a hydraulic engineer will be involved. The hydraulic engineer may be engaged by the principal or, where the head contract is a design and construct contract, the head contractor.
Residential projects
Where a head contract is a design and construct contract, the head contractor may, instead of engaging a hydraulic engineer, seek to engage a plumbing subcontractor pursuant to a design and construct subcontract. In that case, the head contractor is relying solely on the plumbing subcontractor with respect to the design work.
Therefore, even if the subcontract does not specify that the scope includes design work, often a reasonable amount of design work is required.
Alternatively, the head contractor might engage a hydraulic engineer and also engage a plumbing subcontractor pursuant to a design and construct subcontract. In that case, both the hydraulic engineer and the plumbing subcontractor concurrently have design obligations to the head contractor.
For residential builds, often there will not be a detailed plumbing design available to the plumbing subcontract that specifies precisely how each part of the plumbing works is to be installed / constructed.
Where a builder seeks to engage a plumbing subcontractor, it is important that, before any subcontract is agreed, the plumbing subcontractor obtains whatever plans and specifications have been prepared (possibly by the builder or an engineer) and determines the extent to which further design work is required. Where a substantive amount of design work is required: • It is important to discuss with the builder what the process will be with respect to finalising the design. • If the builder indicates that the design work will be completed without the plumbing subcontractor having to be substantively involved, then a plumbing subcontractor should ask for more details to be provided so that they can accurately quote for the work. • If the builder indicates that the plumbing subcontractor is to substantively finalise the design themselves, then it is important that the plumbing subcontractor confirm what design outcomes the design is required to achieve. Also, it is a good idea to ensure that the scope of the design work is clearly set out in the subcontract (although it is often the case that subcontracts for residential builds are quite brief).
Where the plumbing subcontractor is engaged pursuant to a design and construct subcontract, the plumbing subcontractor may decide to undertake the design work in-house. Alternatively, the plumbing subcontractor could itself engage a hydraulic engineer. Given the various possible permutations, it is important that each party is clear on what its obligations are. For example, if the head contractor has engaged a hydraulic engineer and, in addition, engaged the plumbing subcontractor pursuant to a design and construct subcontract, it is important that the contracts are clear as to what design work each party is expected to undertake. Where the head contractor does not engage a hydraulic engineer and simply engages the plumbing subcontractor pursuant to a design and construct subcontract, all the design responsibilities fall on to the plumbing subcontractor. This may be a cost saving exercise by the head contractor. In that case, the plumbing subcontractor needs to be particularly aware of the design objections and its design responsibilities, which should be clearly set out in the subcontract.
Where the plumbing subcontractor is expected to provide a quote with respect to undertaking substantive design work and installation / construction work, it can be difficult to quote for a job where significant amounts of the design detail are not finalised.
The problems referred to above with respect to quoting for residential work where the design is not complete also apply to design and construct contracts in commercial projects.
A contract on an hourly rate (and/or on a costs plus basis) can overcome this, but the builder may want to lock in a price.
Also, it is often not an option to enter into a subcontract for the design work and then a subsequent separate subcontract for the installation / construction work.
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