FENSA is the scheme that lets a window installer self-certify building regulations compliance without a separate building control application.
FENSA (Fenestration Self-Assessment) is a competent person scheme for window and door installers in England and Wales. Registered installers can self-certify that their work complies with building regulations, chiefly Part L for energy efficiency, and notify the local authority on the homeowner's behalf, avoiding the need for a separate building control application and inspection.
Certass and a small number of other schemes operate on the same basis. What matters practically is that your installer is registered with one of them, not necessarily which particular scheme.
It does not, on its own, confirm planning permission or listed building consent, which are entirely separate matters and remain the homeowner's responsibility to establish before work begins.
Conveyancing solicitors routinely ask for FENSA or Certass certificates for any window or door replacement carried out during a homeowner's ownership. Without one, a buyer's solicitor may request indemnity insurance or evidence that the work otherwise complied with building regulations, which can slow down or complicate a sale.
It is still possible to have replacement windows fitted by a non-registered installer, but in that case building regulations compliance needs to be demonstrated through a building control application submitted separately, with an inspection and a completion certificate issued by the local authority instead.
| Route | Who handles notification | Typical cost implication |
|---|---|---|
| FENSA/Certass registered installer | Installer self-certifies and notifies | Included in most installation quotations |
| Non-registered installer | Homeowner applies to building control separately | Additional building control fee applies |
Questions
If your question isn’t here, we would rather talk it through properly than guess.
Ask us directlyVisit the Knowledge CentreKeep reading
Flagship guide · 10 min read
From the first conversation about draughty windows to the day the fitting team leaves, a glazing project has a natural sequence. This guide sets it out in full, so you know what to expect and when.
Planning & Regulations · 3 min read
Building regulations apply to nearly every window and door replacement, regardless of planning permission, and cover far more than just thermal performance.
Planning & Regulations · 3 min read
Part L is the specific regulation that sets the minimum energy performance for replacement windows and doors. Here is what it actually requires.
Installation · 3 min read
Guarantee paperwork can look dense, but the principles are straightforward. Here is what is usually covered, for how long, and what to check.
Build your own collection of expert advice as you plan your project.
Wondering how this applies to your own home?
Share a photograph and we’ll turn this guidance into recommendations for your property.
Ready to understand the likely investment?
Start your personalised Project Investment Guide and see comparable completed projects.
Begin
Bring us your drawings, your site photographs or simply an idea. We will tell you what is possible, what it should cost and how long it will take.
