Replacement windows and doors are controlled work under the building regulations. Somebody has to confirm the new units meet the current standards for thermal performance, safety glazing, means of escape and ventilation. That can be done by your local authority, at a fee and with an inspection, or by a registered installer self-certifying the work.
FENSA is the self-certification scheme most window companies register with. When we finish a job, the installation is notified and a certificate is issued in the homeowner's name, usually within a few weeks. It records the address, the date and the fact the work complied.
What it does not do is guarantee the product. That is a separate insurance-backed guarantee, and the two documents are often confused. When you sell the house, the buyer's solicitor will ask for the FENSA certificate for any glazing installed after April 2002 - a missing one usually ends up as a retention or an indemnity policy at the last minute.
Keep both documents together with the deeds. If you have lost a certificate for work we carried out, we can usually retrieve the record from the address alone.
