Small building works are often signed off under an 'architect's certificate'.  If the consultant signing it is not a registered architect, it is known as a professional consultant's certificate.  Although in common use, they should be approached with great care.  Architects and professional consultants' certificates are promoted by the Council of Mortgage Lenders (the CML).  Their purpose is to provide a reliable level of comfort to subsequent purchasers of the property and their mortgagees - whom the CML represents.

However an architect's or a professional consultant's certificate does not usually provide cover for the original building owner.  So where, for example, an owner extends or carries out structural work to the house, a certificate would be unlikely to give him recourse to the architect (and his insurers) if the latter had been negligent.

Nevertheless a subsequent purchaser's mortgagee would be likely to accept the certificate as sufficient protection against the risk of defects in the building.

Equally it is important to remember that a certificate is only the consultant's confirmation that on visual inspection the work appears to have been built to a satisfactory standard and generally compliant with drawings approved under the building regulations.  It is not a warranty about the sufficiency of the design or that the building is free from defects.

A certificate does not provide cover in the same way as an NHBC guarantee or latent defects insurance policy.  Liability lasts for six years and not ten and (unlike cover for latent defects) there is no liability for construction defects which could not have been noted by the consultant on visual inspection.

An NHBC guarantee requires the builder to put right structural defects and provides cover if he is insolvent.  A certificate will not do this.  For these reasons, building owners and purchasers/investors in a new build property should be very cautious about accepting an architect's or professional consultant's certificate in place of an NHBC guarantee or latent defects insurance.

An owner who has engaged a builder to carry out works to his existing property would, in the event of defects, probably be unable to recover damages from the architect under the certificate and potentially under the original appointment if it could be shown that in accepting the certificate he had waived any further rights against the contractor.