Window Installation Certificates and Guarantees: What You Should Receive

After a window or door installation you should receive a competent person scheme certificate confirming the work meets Building Regulations, plus a written product guarantee from the manufacturer and a workmanship guarantee from the installer. Keep all three. The certificate is the document a buyer’s solicitor asks for, and without it a conveyancing solicitor can hold up a sale.

Paperwork is the least interesting part of a window installation and the part that causes the most trouble years later, usually at the point of sale. A buyer’s solicitor asks for the certificate, nobody can find it, and a straightforward transaction gains a fortnight and an indemnity policy. It is worth ten minutes now to understand what you should have. If you have not yet had work done, our guide to what to expect during a window installation covers the practical side.

What is a competent person scheme certificate?

Replacement windows and external doors are notifiable work under the Building Regulations, which means someone has to confirm the installation complies. There are two routes. Either the installer is registered with a competent person scheme and self certifies, or a building control application goes to the local authority and they inspect. Almost all domestic window work goes down the first route, because it is quicker and cheaper.

Under the self certification route the installer notifies the scheme after completion, the scheme registers the work against your address, and a certificate is issued to you. The scheme confirms the installer’s competence and audits a sample of their installations. Guidance on the competent person schemes and how they operate is published on gov.uk.

What should the guarantees actually cover?

There are normally two, and they are separate documents covering different risks. Confusing them is the reason many claims start badly.

The distinction that matters most is between a sealed unit failing and a sealed unit leaking around its perimeter. A misted unit is usually a product failure and sits with the manufacturer’s guarantee. Water tracking in at the frame to wall junction is usually workmanship and sits with the installer. A good installer will not make you referee that argument, but knowing which document applies helps you raise it correctly. The same split applies to conservatories and orangeries, where the structural work and the glazing may carry different terms.

Does a guarantee transfer when I sell?

It depends on the wording, so read it rather than assuming. Many product guarantees are given to the original purchaser and are not transferable, while others transfer to a subsequent owner either automatically or on notification and sometimes for a fee. Insurance backed guarantees commonly do transfer. This is a reasonable question to ask before you order, because a transferable guarantee is a modest selling point later and costs nothing to specify at the outset.

The scheme certificate is different: it is a record of compliance registered against the property, so it effectively runs with the house regardless of who owns it. That is precisely why buyers’ solicitors ask for it and why it is worth keeping with the deeds rather than in a kitchen drawer.

What if I cannot find the certificate?

First, ask the scheme. Because the work is registered against the address, most schemes can issue a duplicate certificate on request, usually for a small administrative fee, provided you can tell them roughly when the work was done and ideally who did it. That is the quickest route and it resolves most cases.

If the work was never notified, that is a different problem. The remedy is a regularisation application to local authority building control, which assesses the work as built and, if satisfied, issues a regularisation certificate. It is slower, may involve opening up part of the installation, and the outcome is not guaranteed. The gov.uk guidance on building regulations approval sets out the routes. In a sale, many buyers instead accept an indemnity insurance policy, which is cheaper and faster but covers the risk rather than fixing the compliance gap.

What drives the cost of getting this right?

For a normal installation, none of it is a separate line item worth negotiating. Scheme registration and the certificate are part of what a registered installer does, and the product guarantee comes with the product. Where cost does appear is in the insurance backed guarantee, which is sometimes offered as an option and sometimes included, and it is worth asking which. The premium is modest relative to the job and it is the only one of these documents that protects you against the installer disappearing.

The expensive version of this is doing it retrospectively. A regularisation application carries a local authority fee, may require opening up work, and can occasionally lead to remedial work if the installation does not meet the standard. Compared with that, confirming at the point of order that your installer is scheme registered and will issue a certificate costs nothing. Ask the question before the deposit, not after. Our about page sets out our own registrations, and you are welcome to check them independently.

Frequently asked questions

Ask the question before you order

The whole of this comes down to one conversation at the quotation stage: which scheme is the installer registered with, what guarantees are included, and is there an insurance backed guarantee. Any reputable installer will answer all three without hesitation. If you would like to discuss a replacement and see exactly what documentation comes with it, our team covers Staffordshire and the surrounding area.