As you build your new home, certain aspects of its construction and performance need to be approved by different building industry professionals, such as structural warranty providers, registered electricians and commissioning engineers.
Organising these certificates and the paper work that goes with them gathers pace as the completion date nears, but don’t get so caught up in last-minute construction details that you fail to obtain these approvals: your local building control will not issue a completion certificate until you have them all.
If you obtained a 10-year structural warranty scheme to secure a mortgage for your self-build project, the policy issuer will provide a completion certificate after the final inspections are done. This building defects insurance document (also called latent defects insurance), along with the Building Control Completion Certificate, needs to be kept in a secure location, as you can use it to claim a VAT rebate.
When your home is hooked up to the power grid and the first and second fix have been completed, you will need a final certificate from an electrician registered under the Part P scheme. They will test the circuits and produce the certificate if the results are satisfactory.
During the planning or early stages of your build energy efficiency calculations will have been worked out including an air tightness value. A result lower than 15 will need to be verified after completion by a member of the Air Tightness Testing and Measurement Association, who will carry out the test and certify the result.
During the test, a portable seal will be placed over your new home’s front door and air from a large fan will be sent into the house to create a pressure of 50 Pa (pascals). The reduction of air pressure via leakage is timed to work out the actual air tightness value.