Extraglaze Secondary Glazing

Secondary glazing designed to enhance comfort while preserving your building’s character

Owners of listed and period properties face a unique challenge: improving warmth, comfort, and energy efficiency without altering the original windows that define the building. Extraglaze secondary glazing is designed specifically for this environment — discreet, reversible, and trusted by homeowners and Conservation Officers alike.

At a glance

• Near‑invisible, frameless insulation panels
• Reversible and conservation‑friendly
• Approved by Conservation Officers
• Significant warmth and condensation improvements
• Protects original windows in a “museum‑cased” environment
• Ideal for Grade I, II* and II listed buildings

Why listed-property owners choose Extraglaze

From our independent Feefo reviews we know that Extraglaze is one of the highest‑rated secondary glazing solutions in the UK. Homeowners in Grade II and conservation‑area properties repeatedly highlight three things:

• Near‑invisible appearance that preserves the look of original sash and casement windows
• Dramatic improvements in warmth and comfort, even in the coldest rooms
• Significant reduction in condensation, especially on single‑glazed sashes.

Many customers have told us that their installations were approved by Conservation Officers, giving reassurance that Extraglaze meets heritage expectations for minimal visual impact and reversibility.

“They were immediately approved by the Conservation Officer and have led to a noticeable improvement in warmth…”
— Verified Feefo review, Grade II Victorian home

This combination of heritage sensitivity, proven performance, and exceptional customer satisfaction makes Extraglaze a standout choice for listed buildings.

Designed for heritage: discreet, reversible, respectful

Listed‑building owners often worry that secondary glazing will look bulky or modern. Extraglaze is engineered to avoid exactly that.

• The ultra‑slim, frameless insulation panels sit close to the existing window and blend into the background
• Reversible installation protects the original fabric of the building
• No structural changes are required, making it suitable for Grade I, II*, and II properties
• Custom shapes accommodate arches, curves, bays, and irregular period features.

Customers frequently describe the panels as “almost invisible” once installed — a key reason Conservation Officers respond positively.

Why Conservation Officers approve Extraglaze

Conservation Officers typically look for four things:

• Reversibility
• Minimal visual impact
• Protection of original fabric
• Is it seen from outside? (With Extraglaze’s frameless design, the answer is no).

Extraglaze aligns with all four.

“…nothing does us more proud than receiving some approving looks or blatant praise from a local Conservation Officer.”

Combined with verified customer reviews confirming explicit approval, you can confidently state that Extraglaze is a conservation‑friendly solution.

Independent reviews: real results in real listed homes

Across hundreds of Feefo reviews, customers consistently highlight:

• “Rooms are much warmer”
• “Condensation dramatically reduced”
• “Almost invisible once fitted”
• “Beautifully made and very high quality”
• “Easy to install with clear instructions”
• “Excellent customer service from start to finish”.

These are not marketing claims — they are independent, verified experiences from people living in the same kinds of homes as your prospective customers.

Performance that respects your building

Extraglaze improves comfort without compromising heritage value:

• Thermal insulation reduces heat loss through single glazing
• Acoustic insulation softens traffic noise and urban sound
• Condensation control protects timber frames and reduces mould risk
• Draught elimination makes rooms feel warmer even before the heating comes on.

Your original windows also become “museum‑cased”. They are protected from condensation, black mould, and long‑term deterioration. Because the air inside the cavity is always warmer than outside, the original frames remain in a gentle, continuous drying‑out mode — ideal for preserving historic timber.

For many listed‑property owners, this is the only acceptable way to improve energy efficiency without altering original windows.

Perfect for Grade I, II*, and II listed buildings

Because Extraglaze is reversible and visually discreet, it is widely accepted as a sympathetic upgrade for:

• Georgian townhouses
• Victorian terraces
• Edwardian villas
• Timber‑framed cottages
• Historic farmhouses
• Converted mills, schools, and chapels.

Where double glazing is prohibited, Extraglaze provides a compliant, conservation‑friendly alternative.

A respectful installation process

Whether fitted by you or by a professional:

• No mess, no disruption
• No changes to the original window
• No drilling into historic frames
• Panels can be removed for cleaning or ventilation (no tools required).

This is especially valued in homes with delicate joinery or original shutters.

A trusted choice for heritage homes

Extraglaze has earned its reputation not through claims, but through consistent results and independent customer feedback. For listed-property owners, the reassurance is clear:

• It preserves the building’s character
• It improves comfort dramatically
• It aligns with conservation principles
• It has real‑world Conservation Officer approval
• It is backed by exceptional customer satisfaction.

Nic Irvine, co-founder of Extraglaze, was a guest speaker at a conference consisting primarily of Conservation Officers.

Read more …

This offer is designed with a purpose: to help customers try out Extraglaze in their homes - then decide whether or not they love Extraglaze. This offer is nevertheless valid for returning customers.

There is no upper limit to the value of any order you place, but the order must include one or more DIY Extraglaze panels. Orders containing any number of Saverglaze panels are excluded from this offer.

You must place your order and successfully pay for it on 8th February through 31st March 2025*.

Orders may take longer to priocess than suggested by our web site, for many reasons. For example this promotion may generate many orders, consequently increasing the orders in the queue for processing. By placing an order you fully accept that it may not be ready within any suggested or confirmed delivery period, and that your order will be processed in every other respect regardless. 

Existing orders will not qualify (please don't try to cancel an existing order and place it again).

Free delivery shall mean within Mainland UK. For customers in the Highlands & Islands, Northern Ireland, Isle of Man and the Channel Islands we will discount your delivery price by an amount equivalent to a mainland order delivery price and reserve the right to charge you a supplement to cover the additional costs as would be associated with such far-afield deliveries - this supplement will be discussed with you, for your approval before we proceed with your order, and you will have the option to cancel your order until payment for the supplement has been received. If you believe this is likely to apply to your order then contact us immediately.

Orders will not qualify for this offer if you request any addition or some kind of modification after the offer period (or after it has been withdrawn if sooner): our standard conditions will be applied and you will have to place a new order and pay a standard price for delivery.

We will notify you when your order is ready to be dispatched and you must accept delivery within 2 calendar weeks of this notification, or the offer will be withdrawn, requiring you to pay our standard cost of delivery (our web site will calculate the cost: simply add a duplicate order into your Basket i.e. without completing the Checkout process).

Goods or services rendered after the offer period will not qualify, for example: if you have to send back panels for resizing then a charge for collection and redelivery will apply - to be agreed and paid for by you in advance.

This offer is strictly limited to the delivery price and shall not reduce the prices for any goods or services. Our standard terms and conditions are not affected. If you choose to collect your order then this offer will be considered waived by you in all respects.

Extraglaze Ltd reserves the right to judge what does and does not qualify as meeting the spirit of the purpose of this offer, and may consequently, within 5 business days of receiving payment, advise you that the offer will not apply to your order and what delivery price we will apply instead, in which case the order will be stalled (nothing will be made for you) after which you will have the right to cancel your order for a full refund, or advise us to proceed on payment of the applied delivery price. When we receive your decision in writing to proceed our other standard conditions shall apply (for the avoidance of doubt the order may not thereafter be cancelled so no refund will be available). Each order will be treated individually in this regard. Therefore each application of this offer shall be entirely at the discretion of Extraglaze.

* NOTE: this offer period is not guaranteed and may be withdrawn at any time.

Extraglaze reserves the right to modify (including to extend or remove) this offer at any time. A version number will apply to your order: see the "date stamp" in the next line below.
Version 1.0 applies from midnight 7th February to midnight on the end date).