The Bit of Paper That Outlives Your Windows: Who Actually Certifies the Job
You can agonise over the frame colour for a fortnight, compare g-values until your eyes glaze over, and then discover — usually about four years later, halfway through a house sale — that the job was never certified. It happens a lot. Not because homeowners are careless, but because certification is the one line item that quietly falls off a quote and nobody notices until it matters.
So here's the plain-English version, no jargon, no sales patter.
What FENSA and Certass actually are
Neither is a brand of window or a type of guarantee. They're competent person schemes — government-approved bodies that let registered installers self-certify their own work as compliant with the Building Regulations.
In England and Wales, that means the relevant parts of the regs covering energy performance (Part L), ventilation (Part F), glazing safety (Part K) and impact resistance (Part N). When a scheme member fits your windows, they notify the scheme, the scheme notifies your local authority, and you get a certificate through the post or by email. Job done, paper trail intact.
If your installer isn't in a scheme, the work still has to comply. But the notification becomes your problem, not theirs. You ring Building Control, pay a fee (commonly somewhere between £100 and £300 depending on the authority and the size of the job), and possibly arrange for an inspector to look at the work — sometimes before it's finished. That's a chunk of your weekend you weren't planning on spending.
Scotland and Northern Ireland run their own building standards systems rather than FENSA and Certass as such, but the principle holds: somebody has to sign the job off, and it's worth knowing who before the scaffold goes up.
Why it follows you around for years
Here's the bit that surprises people. Your windows will outlast your memory of the quote, and when you sell, the buyer's solicitor sends a standard set of enquiries that includes a question about replacement windows and Building Regulations compliance.
No certificate? Then it's one of three outcomes. You dig out paperwork and hope. You pay for a regularisation application through Building Control. Or you buy an indemnity policy — a cheap insurance product that protects the buyer's lender against enforcement action, but does precisely nothing about whether the windows were fitted properly.
None of those are disasters. All of them cost time and money, and all of them hand the buyer's side a small lever to push on price. Estate agents will tell you the same thing: missing building regs paperwork is a classic completion-date killer.
Where it quietly slips out of a quote
Read the small print with a slightly suspicious eye. These are the patterns worth spotting:
- 'Certification available on request.' Translation: not included. Ask what it costs.
- A separate notification fee buried at the bottom. Perfectly legitimate — but it should be visible and explained, not discovered on page four.
- Nothing at all. Some installers simply aren't registered. They may be excellent fitters. They still can't self-certify.
- 'Fully guaranteed.' A guarantee covers workmanship or products. A certificate confirms regulatory compliance. They are not the same thing, and one doesn't substitute for the other.
There's a subtler trap too: lapsed membership. A firm can carry the logo on the van for years after its registration has quietly expired. Schemes publish online registers — search the exact company name and check it's live, not just present.
Three questions that settle it
Ask these before you sign anything, and ask for the answers in writing on the quote:
- Are you currently registered with FENSA or Certass — and what's your registration number? A real member will give it without blinking.
- Is the notification fee included in this price? If it's extra, fine, but it belongs on the quote, not in a conversation.
- Will the certificate come to me directly, and roughly when? Typically a few weeks after completion, but get the expectation set.
Worth adding a fourth: what happens if the firm stops trading before the notification goes through? Some schemes offer insurance-backed protection, but the terms vary. Check rather than assume.
What the certificate isn't
It's a compliance document, not a quality report. It won't tell you whether the sill was sealed properly, whether the reveals were made good, or whether that one window in the back bedroom sticks in August. Those are warranty and aftercare matters — separate conversation, separate paperwork.
It also doesn't cover everything. Conservatory roofs, garden rooms, and some structural alterations sit outside the standard window notification. Don't assume one certificate covers the whole extension project.
The straight-talking summary
Certification is a small slice of the overall cost and a bit of admin for the installer. That's exactly why a firm that hums and haws about it is telling you something useful. Ask early, get it itemised on the quote, and file the certificate with your deeds the day it lands.
Your future buyer's solicitor will ask. Better that you're the one with the answer already in a folder.
