Replacing windows and doors: Essential paperwork to keep

Replacing external windows and doors is one of the most common home improvements carried out in England and Wales. It is also one of the areas where paperwork is most frequently misplaced or misunderstood. Because new glazing must meet statutory standards for energy efficiency, safety, and ventilation, having modern units fitted is only half the job. You also need to retain the documentation that proves the installation was completed in accordance with the law.

Building Regulations and why glazing is controlled

Since April 2002, the replacement of external windows, rooflights, and glazed doors has been controlled under Building Regulations in England and Wales. The regulations apply whether you are replacing a single draughty sash window or installing whole-house double or triple glazing. The rules ensure that replacement units meet specific minimum standards across several technical areas:

• Thermal efficiency (Part L): Requiring glass and frame assemblies to meet maximum allowable U-values to minimise heat loss from the dwelling.
• Safety glazing (Part K): Requiring toughened or laminated safety glass in critical locations, such as low-level glazing and doors.
• Ventilation (Part F): Ensuring adequate background ventilation is maintained, typically through trickle vents or controlled mechanical ventilation.
• Fire safety and escape (Part B): Maintaining or improving emergency egress window openings in habitable rooms.
• Security (Part Q): Applicable to new dwellings and certain material alterations, governing forced-entry resistance for accessible doors and windows.

The core documents you should receive

When replacement windows or external doors are installed, the exact paperwork you receive depends on who carries out the work. In every case, you should expect to collect a complete set of compliance and warranty records before settling the final account.

If you use an installer registered with an authorised Competent Person Scheme (such as FENSA, CERTASS, or Assure), the contractor can self-certify that the installation satisfies Building Regulations. The installer notifies your local authority on your behalf, and the scheme operator issues a certificate directly to you. This document acts as official confirmation that the local authority was notified and that the work met the required technical standards at the time of installation.

If you employ an unregistered builder, fit the units yourself, or carry out installations that fall outside the scope of self-certification, you must submit a Building Notice directly to your local authority Building Control team or an approved inspector before work begins. Following an on-site inspection of the finished work, Building Control issues a formal Building Regulations completion certificate.

Alongside statutory compliance certificates, you should collect product specification sheets, itemised invoices, and the written manufacturer warranty. Glazing units and frames commonly carry five- to ten-year warranties against seal failure, warping, or discolouration. You should also ensure you receive an Insurance-Backed Guarantee (IBG), which protects the installer's workmanship warranty if the company ceases trading during the guarantee term.

Special circumstances: Listed buildings and structural openings

Competent Person Scheme certificates only demonstrate compliance with Building Regulations; they do not convey planning permission or listed building consent. If your property is a listed building, sits in a conservation area covered by an Article 4 direction, or is subject to restricted permitted development rights, you must obtain written planning approval before altering window designs, frame materials, or sightlines. Keep copies of planning decision notices and any discharge of condition letters with your glazing files.

Similarly, if your project involves widening an existing opening—such as cutting back masonry to fit wide bi-fold or sliding patio doors—the work includes structural alterations. While the glazed door assembly itself can be self-certified for thermal performance, the installation of the structural lintel and load-bearing support requires separate Building Control sign-off and structural calculations.

Why keeping glazing records matters

When you come to sell your home, your conveyancer will ask you to complete the Law Society Property Information Form (TA6). Section 8 of the form specifically asks whether replacement windows, roof windows, or external doors have been installed since 1 April 2002, and requires you to provide copies of the relevant Building Regulations completion certificates or Competent Person Scheme certificates.

Missing certificates frequently lead to delays during conveyancing, requiring sellers to pay for duplicate certificates or negotiate indemnity policies. Storing clear digital copies of your certificates, specifications, and warranty documents on an independent record-keeping platform like Project Passport ensures your property documentation remains organised and easily accessible throughout your ownership.

Thorough record-keeping also protects your investment day-to-day. If a sealed unit fails and mists up between panes, or if a multi-point locking gearbox requires replacement years later, having the original product codes, glass specifications, and installer warranty details to hand makes repair work straightforward.