New windows and home insurance UK (2026)

Every year, thousands of UK homeowners invest thousands of pounds in new double or triple glazing, watch the fitters pack up their van, and then consider the job entirely done. The windows look beautiful, the draughts have gone, and the heating bills are already beginning to fall. What very few of those homeowners do in the days that follow is pick up the phone to their insurer. That single overlooked conversation can have serious consequences — from a reduced insurance payout to a claim being refused altogether. With home insurance premiums continuing to rise sharply across the UK in 2026, getting this administrative detail right has never been more important or more worthwhile.

This guide walks you through exactly what you need to tell your insurer, when to tell them, how the security specifications of your new windows can actually work in your favour, and which documents you should keep safe for years to come. Whether you have just had standard uPVC double glazing fitted or gone all-out with heritage timber sash windows in a conservation area, the same principles apply.

Why Telling Your Insurer About New Windows Actually Matters

Home insurance is a legal contract built on a principle called “utmost good faith.” In practice, this means both you and your insurer are obliged to be completely honest with each other about anything that could affect the risk being covered. As a policyholder, your obligation does not end when you first take out the policy — it continues throughout the life of that contract. Any significant change to your property needs to be disclosed.

Replacing windows qualifies as a significant change in most cases, particularly when you are altering the type of glazing, switching frame materials, or upgrading the security specification. The reason insurers care about this is straightforward: the windows in your home directly affect the risk of weather damage and break-ins, both of which are among the most common types of insurance claims.

According to the Association of British Insurers (ABI), homeowners have an ongoing duty to keep insurers informed of material changes to their property. The ABI’s guidance on this is publicly available on their website and is well worth a read if you want to understand your obligations in detail. Failing to comply with this duty can result in a claim being significantly reduced — or refused entirely. This is particularly relevant if you ever make a claim involving a burglary (where the point of entry was a window) or storm damage to the glazing itself.

The good news is that notifying your insurer is genuinely simple. For most people, it is a ten-minute phone call or a quick update through their insurer’s online portal. The harder part is remembering to do it — and knowing exactly what to say when you do.

Practical tip — add “call insurer” to your installer booking confirmation so it appears on your calendar the day the job is completed.

What Counts as a Material Change When Replacing Windows

The phrase “material change” is insurance jargon for anything that would affect how your insurer assesses the risk of insuring your home. In plain English, if the information would have changed the terms, price, or decision your insurer made when they agreed to cover you, it is material and needs to be disclosed.

For windows, the following scenarios are almost always considered material changes and should be reported without delay.

• Upgrading from single to double or triple glazing — this is generally a positive change from an insurer’s perspective, as modern glazing is more resistant to both weather damage and forced entry
• Changing frame material — switching from timber to uPVC, or from uPVC to aluminium, affects the security rating, thermal performance, and rebuild cost of your property
• Installing non-standard or oversized windows — large picture windows, bifold doors replacing a standard window opening, or floor-to-ceiling glazing all alter the structural and risk profile of your home
• Adding or removing a window entirely — bricking up an existing window or cutting a new opening into an external wall is always notifiable, regardless of how minor it may seem
• Installing windows in a listed building or conservation area — these situations involve planning consent and specialist materials, both of which affect your insurance position significantly

What does not typically count as a material change is like-for-like maintenance replacement — for example, replacing a single failed sealed unit in a window of the same type, size, and specification. However, if you are in any doubt, the safest approach is always to notify your insurer and let them make the assessment.

Practical tip — if your replacement windows are a different frame material, glazing type, or security specification from what you previously had, treat it as notifiable. When in doubt, disclose.

How Window Security Ratings Can Lower Your Home Insurance Premium

Here is the genuinely good news about upgrading your windows: if the new products carry recognised security certifications, you may be able to negotiate a lower premium on your buildings and contents insurance. This is one of the most under-used use points available to homeowners, and it costs nothing to ask.

The two key standards that UK insurers recognise are PAS 24 and Secured by Design (SbD).

PAS 24:2022 is the enhanced security performance standard for windows and doors in the UK. Products certified to PAS 24 have been independently tested against a range of physical attack scenarios, including attempts to lever, cut, or force the frame and glazing. Many building regulations now require new and replacement windows to meet this standard as a baseline — but not all windows sold in the UK automatically carry PAS 24 certification, so it is worth checking your product specifications.

Secured by Design is a police-backed initiative operated by the Association of Chief Police Officers Crime Prevention Initiatives (ACPO CPI). Windows and doors bearing the SbD accreditation meet or exceed PAS 24 requirements and have been assessed by the police’s own crime prevention specialists. The SbD logo is widely recognised by UK insurers as a credible indicator of quality.

Many UK insurers offer a discount on premiums when windows and external doors meet these standards. The exact discount varies considerably between providers, and we would not want to quote a figure here that does not apply to your specific insurer — but it is entirely reasonable to call your insurer, explain that your new windows carry PAS 24 or SbD certification, and ask directly whether this qualifies you for a review of your premium. You are, after all, reducing their risk.

Guide to PAS 24 certified windows and doors

Practical tip — ask your installer to confirm in writing whether the windows they are fitting carry PAS 24 or SbD certification before you sign the contract. This costs nothing extra and is worth its weight in insurance negotiations.

The Documents You Should Keep After Window Installation

The paperwork that comes with a window installation is not just bureaucracy — it is evidence. Evidence that protects you if an insurer ever questions the specification of your glazing, evidence that you need when you sell your home, and evidence of compliance with building regulations that could save you from serious legal complications further down the line.

Here is exactly what to keep, and why each document matters.

FENSA or CERTASS Certificate

In England and Wales, replacement windows must be installed by a contractor registered with either FENSA or CERTASS, or alternatively the homeowner must make a separate Building Regulations application to their local authority. FENSA and CERTASS are government-authorised competent person schemes — registration with either body allows installers to self-certify that their work complies with Building Regulations without the homeowner needing a separate council inspection.

Your FENSA or CERTASS certificate is proof that the installation was legal and compliant. Without it, you may face difficulties when you sell your property, and your insurer may question the legitimacy of the installation. Keep this certificate with your deeds and other property documents — never just in the kitchen drawer.

Manufacturer’s Performance Specifications

The paperwork supplied with your windows should include details of the product’s security rating (including any PAS 24 certification number), its energy rating under the British Fenestration Rating Council (BFRC) scheme, and any Secured by Design accreditation. This is the document you reference when calling your insurer to discuss a premium review.

Installer’s Guarantee and Warranty

Most reputable window installers offer a ten-year guarantee on frames and a separate guarantee on sealed units. These are legal commitments to repair or replace defective products and workmanship — keep them somewhere accessible, along with the installer’s contact details.

Photographic Evidence

Take dated photographs of the completed installation before you tidy up. Capture the locking mechanisms, multipoint locking systems if fitted, hinge locations, and the overall condition of frames and glazing. These images can be invaluable if a claim ever involves your windows, as they provide a baseline record of the specification and condition at the point of installation.

Planning Documentation

If your property is listed or situated in a conservation area and you required planning permission or listed building consent for the window replacement, keep all planning correspondence alongside the installation paperwork. This is non-negotiable from both an insurance and a legal standpoint.

Practical tip — create a dedicated folder (physical or digital) labelled “Windows [year of installation]” and keep all of the above documents together. Scan physical documents and keep a digital backup in cloud storage.

When to Contact Your Insurer and What to Say

Do not wait until your renewal date to inform your insurer about new windows. Contact them as soon as the installation is complete — this is the correct approach under the principle of utmost good faith, and it also means any security-related premium benefits take effect immediately rather than months down the line.

Most insurers have a mid-term adjustment process that allows you to update your policy details at any point during the year. You can typically do this by phone, email, or through your insurer’s online account portal — whichever is most convenient for you.

When you contact them, have the following information ready.

• The date the installation was completed
• The type of glazing installed (double or triple, and the glazing specification if known)
• The frame material (uPVC, aluminium, timber, or composite)
• Whether the windows carry PAS 24 certification or Secured by Design accreditation
• The name of the installing company and their FENSA or CERTASS registration number
• Whether the number of windows in the property has changed

Once you have provided this information, ask the insurer directly whether the upgrade qualifies for a premium review. Be specific — mention the PAS 24 or SbD certification by name. It is also worth asking whether the higher specification of your new windows means the rebuild cost estimate on your buildings insurance should be reviewed upward. This is particularly relevant if you have installed heritage timber sash windows, large aluminium bifolds, or triple-glazed units, all of which carry a significantly higher replacement cost than standard uPVC.

What affects the cost of replacing windows in the UK

Practical tip — make a written note of the date you called, the name of the adviser you spoke to, and a summary of what was agreed. This creates a record that the change was disclosed properly.

Comparing Window Types and Their Insurance Relevance

The table below gives an at-a-glance comparison of common window types available to UK homeowners in 2026, their typical security standards, insurance considerations, and approximate supply-and-fit costs. These costs are approximate UK averages based on industry installer data and published ranges from TrustMark-registered businesses — always obtain at least three quotes for your specific property and location.

secondary glazing vs double glazing — which is right for your home

New Windows and Your Buildings Insurance Sum Insured

Your buildings insurance sum insured is not the market value of your home — it is the estimated cost of rebuilding it from scratch if it were completely destroyed. This figure needs to reflect the actual cost of materials and labour, and in 2026, both of those have continued to rise following years of sustained inflation in the construction sector.

If your new windows are significantly more expensive to replace than the windows they replaced, your sum insured may now be too low. This matters because of a concept called underinsurance — if your home is insured for less than it would actually cost to rebuild, your insurer may only pay out a proportionate share of any claim, even one that has nothing to do with the windows themselves.

Consider the following comparison to illustrate the potential gap.

The ABI provides a free rebuild cost calculator on their website that can help you check whether your sum insured remains appropriate. For older, unusual, or listed properties, a chartered surveyor’s rebuild cost assessment is a worthwhile investment — particularly if you have made several improvements to the property in recent years.

Practical tip — treat a new window installation as a prompt to review your entire buildings sum insured, not just the windows in isolation. Material and labour costs have risen significantly in 2026, and many homes are underinsured without their owners realising it.

What Landlords and Short-Term Rental Hosts Need to Know

If you rent out a property — whether on a long-term tenancy, as a House in Multiple Occupation (HMO), or through a short-term rental platform — the notification requirements around window replacements are even more important to get right.

Landlord insurance policies typically carry stricter notification clauses than standard home insurance, and many require advance notice of any significant alteration to the property. Check your specific policy wording carefully — some policies require you to notify your insurer before work begins, not just after it is completed.

If a tenant arranges window replacement without your knowledge or consent, your insurance could be affected. This is a scenario worth addressing directly in your tenancy agreement — clauses requiring tenants to seek written permission before any alterations to the fabric of the building are standard practice for a reason.

Houses in Multiple Occupation may also have specific requirements around window safety under their HMO licensing conditions — for example, requirements relating to emergency escape windows in upper-floor rooms. Any window upgrades should be documented carefully to demonstrate ongoing compliance with licensing conditions.

Short-term rental hosts using platforms such as Airbnb should check whether their host protection policy or specialist short-term rental insurance covers the full replacement cost of upgraded windows in the event of accidental damage. Standard home insurance policies often exclude commercial letting activity, meaning a gap in cover may exist even if the windows themselves meet every security standard.

Landlord insurance and home improvements — what to disclose

Practical tip — if you are a landlord, speak to a specialist landlord insurance broker rather than relying on a standard home insurance policy. The notification requirements and cover terms can differ significantly.

Grants and Financial Support for New Windows in 2026

While the primary focus of this article is the insurance implications of new windows, it is worth briefly noting the financial support that may be available to help offset the cost of the installation itself — because lower upfront costs mean the insurance administration is worth doing even on a tight budget.

The ECO4 scheme (Energy Company Obligation, Phase 4) is the government’s flagship programme for improving energy efficiency in low-income and vulnerable households. ECO4 primarily targets insulation and heating systems, but window upgrades can be included as a secondary measure within a whole-house retrofit for eligible households. According to the Energy Saving Trust, eligibility is linked to income, benefit receipt, and EPC rating — full details are available on their website and on gov.uk.

The Great British Insulation Scheme (GBIS) is focused primarily on single-measure insulation improvements for homes with an EPC rating of D or below. Windows are not a primary measure under GBIS, but eligible properties may be able to bundle glazing improvements within a wider upgrade package — check the current scheme status on gov.uk, as programme details and funding availability are subject to ongoing government review.

Some local authorities also operate local authority flex funding under the ECO framework, which can extend support to a wider range of households and property types than the main ECO4 criteria. Your local council’s website or the Energy Saving Trust helpline are the best starting points for finding out what is available in your area.

It is important to note that none of these schemes guarantee window replacement funding — eligibility is specific to individual households and properties. Always use the official sources above rather than relying on cold-call companies claiming to offer “free windows,” which are a well-documented source of consumer complaints.

ECO4 and glazing — what homeowners need to know in 2026

Practical tip — before assuming you do not qualify for any grant support, spend fifteen minutes on the Energy Saving Trust’s eligibility checker. Many homeowners who could benefit from ECO4 or GBIS do not realise they are eligible.

A Quick Summary of Your Action Steps

To make it easy to act on everything covered in this guide, here is a straightforward checklist of what to do once your new windows have been fitted.

1. Check that your installer is FENSA or CERTASS registered before they begin work, and confirm you will receive a certificate on completion
2. Ask your installer to confirm in writing whether the windows carry PAS 24 or Secured by Design certification
3. Take dated photographs of the completed installation, including all locking mechanisms
4. File your FENSA or CERTASS certificate, manufacturer’s specifications, guarantee documents, and any planning correspondence in a dedicated folder
5. Contact your insurer as soon as the installation is complete — do not wait for renewal
6. Tell your insurer the date of installation, the glazing type, the frame material, the security certification, and the installer’s registration number
7. Ask directly whether the upgrade qualifies for a premium review
8. Ask whether your buildings insurance sum insured should be reviewed upward to reflect the higher specification of your new windows
9. If you are a landlord, check your specific policy wording and notify your insurer in accordance with your policy’s requirements

The ten minutes it takes to notify your insurer after a window installation is one of the most cost-effective things you can do as a homeowner. It protects your claim, may reduce your premium, and ensures that the investment you have just made in your home is properly covered for years to come.

New windows are one of the most impactful improvements you can make to a UK home — for comfort, energy efficiency, security, and kerb appeal. Making sure your insurance reflects that improvement is simply the final step in getting the job properly done.