FENSA Certificate
When having new windows, doors and roof lights installed, the contractor should issue the homeowner with a FENSA Certificate. This shows that the work has been done by an installer who is registered with FENSA or a similar body and that the installation has been approved under the Building Regulations. This removes the need for the homeowner to register the installation with the Local Authority Building Control. If you do not get a FENSA certificate when your new units are installed, you may find that a future sale is held up and you may have to apply to your Local Authority separately for a certificate.
What Is FENSA
FENSA stands for the Fenestration Self-Assessment Scheme. Following Government encouragement, FENSA has been set up by the Glass and Glazing Federation (GGF) and other industry bodies in response to Building Regulations for double glazing companies in England and Wales. When replacing windows, doors and roof lights in dwellings in England and Wales, homeowners must comply with current thermal performance and Building Regulation standards and ensure they get a certificate from a Competent Person scheme such as FENSA or Local Authority Building Control. FENSA enables companies that install replacement windows and doors to self-certify compliance under these Building Regulations without the need for a separate assessment from Building Control.
FENSA obtains funds to supports its certification operations through a combination of membership fees and inspection fees. FENSA does not aim to accumulate or distribute any surpluses, but set its charges at levels appropriate to finance the continuing operation and expansion of its certification product, and to provide prudent reserves against contingencies.

Only a 'Gas Safe' registered engineer can fit a new gas appliance (eg a boiler, cooker or heater) in your home. Once a gas appliance has been installed the Local Authority and the Gas Safe Register have to be notified by the Gas Safe registered engineer. A homeowner will then be sent a copy of the registration.
If you have a new gas appliance fitted your Gas Safe registered engineer should let your Local Authority know. Registered engineers have responsibility for complying with the Building Regulations but the owner of the property is ultimately the one who may be the focus of enforcement action by the Local Authority if the work is not notified. In England and Wales, the Building Regulations require all Local Authorities (LA) to be informed when a heat producing appliance (boiler, fire etc) is installed in a property.
The Building Regulations and Gas Safe rules of registration require that Gas Safe registered businesses comply with their geographical area regulations by notifying (i.e. self-certifying) any relevant appliances they’ve installed to the LA. If you own your property, the responsibility also falls upon you to ensure that Building Regulations are complied with, so it’s in your interest to ensure that an engineer notifies any installation work.
Legal Basis
The Building Regulations in England and Wales make it a legal requirement for the appropriate Local Authority (LA) to be informed about the installation of a heat producing gas appliance e.g. boiler or fire.
See Also In Chimni
Chimni Wiki Home Information Packs - HIPs
Other Interesting Web Sites
http://www.fensa.co.uk/homeowner-info.aspx
References
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