Why windows involve building regulations at all
Replacing a window changes the building's thermal performance, its ventilation and sometimes its escape routes, which is why the work is controlled. The rules set minimum energy performance for the new units, require that ventilation is not made worse, which is why many replacements now include trickle vents, and care about safety glazing in doors and low windows.
None of this lands on you as a homeowner form to fill in, provided the installer handles it the standard way: through a competent person scheme.
What FENSA and Certass actually are
FENSA and Certass are the best-known competent person schemes for glazing. A registered installer self-certifies that the work meets building regulations, registers the job with the scheme, and a certificate arrives in the post a few weeks after installation. That certificate is the proof your solicitor will ask for when you sell the house.
An installer who is not registered with a scheme can still fit windows legally, but the job then needs building control involvement and sign-off, which adds cost and delay. So the practical question for any quote is simple: which scheme are you registered with, and will the job be registered? A confident one-line answer is what you are listening for.
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Compare window and door quotesMissing certificates, and how to compare quotes on this
If you are buying or selling and a certificate cannot be found, do not panic: schemes can reissue lost certificates for registered jobs, and where a job was never registered, building control can grant regularisation or the transaction can proceed with an indemnity insurance policy, an imperfect but common fix. It is a solvable problem that is simply nicer never to have.
The way to never have it is to make the paperwork part of the purchase. Compare quotes from trusted window and door installers, confirm scheme registration on each, and keep the certificate with the house documents when it arrives. Where the property is listed or in a conservation area, a second layer applies before the work starts, covered in planning permission and replacement windows.
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Up to three trusted window and door installers quote for the work. Free, no obligation.
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