Generally and in normal circumstances, the contractor has no liability for design, therefore no liability for the production of design drawings. The question often arises whether the contractor is entitled simply to build what the drawings and specifications set out, even if there are errors on the architect’s drawing. It is not surprising that most architects would say ‘No’, but the case law on this subject is not so clear.
It has been established by a Canadian case that a contractor will be liable to the employer for building errors in a design if the original architect was not involved in the construction stage. The ratio of that case seems to have been that the employer was no longer relying on the architect and, therefore, relied solely on the contractor, which should have taken care to check that everything on the original architect’s drawing worked properly. That, however, is not the situation under consideration here, where the original architect is still engaged, but where there is an error in the drawings. There were two cases in 1984 which held that a contractor did have a duty to warn the architect if it believed that there was a serious defect in the design. Subsequently, however, another court decided that such duty as the contractor might have was to the employer and probably only in those cases where the contractor was aware of the employer’s reliance for at least part of the design. This has echoes of the Canadian case mentioned above. To further confuse matters, another case held that a contractor had a duty to at least raise doubts with the architect if there appeared to be something wrong with the drawings.One would have to wonder at the motives of a contractor who had full knowledge of a drawing error and yet failed to draw it to the attention of the architect.
That position was taken a stage further by a Court of Appeal case. Although this case involved sub-contract work, the principles set out by the court are equally applicable to main contracts. JMH designed the temporary support work to a roof. Unfortunately, its design was overruled by the employer’s engineer, who proposed a different design. There was no question in this instance over whether JMH failed to warn the engineer. They did warn the engineer of the danger of his design quite clearly, but he took no notice and the engineer’s design for temporary work went ahead. Needless to say, the roof collapsed. Surprisingly, the court held, not just that JMH had a duty to warn, which the court seemed to accept had been done, but that they had failed to warn with sufficient force. One cannot help but think that the only degree of warning that the court would have accepted as sufficient would have been if JMH had given the warning and, at the same time, threatened to stop work if the warning went unheeded. This appeared to be the court’s position also.
The contractor’s duty to warn probably arises only if the design is seriously defective. In the case just mentioned, it seems to have been a potential danger to life. A contractor who did not warn an architect who had made a small dimensional error or a small mistake in detailing would be unlikely to have any liability.
The important point to be drawn from these cases is the reliance by the employer on the contractor. If it can be shown that the employer does rely, even partly, on the contractor, it seems that there will be a duty to warn of serious defects. On the other hand, cases where the duty arises to warn the architect will be rare, because the architect seldom, if ever, relies or is entitled to rely on the contractor. In the context of JCT traditional contracts, the duty is likely to be limited, because the employer will usually be relying on the architect and not the contractor. Contractors can take heart that they are not generally responsible for checking the architect’s drawings. Having said that, a contractor proceeding with construction in the certain knowledge that there were errors on the drawings would find little favour with an adjudicator in any subsequent dispute.