Introducing Escence Wood^™: a new way to renew timber windows

There is something in an older New Zealand home that newer joinery rarely reproduces. The depth of a timber reveal. The way a sill sits proud of the wall and catches the afternoon light. Proportions that were drawn for that house, in that era, and that still look right decades later. Homeowners notice it even when they cannot name it, and it is usually the reason they hesitate. Because alongside all of that comes single glazing, draughts, condensation on winter mornings, and a casement that has to be persuaded rather than opened. It is easy to conclude that you must choose: keep the character, or improve the comfort.

That choice is narrower than it first appears. A timber window is not one indivisible object. The part fixed into the building, being the sill, jambs, head, mullions, reveals and architraves, can remain exactly where it is. The glazed panels held within it are a separate component, and they can be renewed independently. Importantly, the original sash does not need to be visibly failing before this becomes a sensible thing to do. A sash can be perfectly sound and still be the limiting factor in how well the window performs.

Escence Wood™ timber sash replacement is an engineered system that replaces original single-glazed sashes with new double-glazed timber sashes installed into suitable existing frames. It is not a repair of last resort. It is a way of renewing the working part of a window while leaving the part that carries the architectural character undisturbed.

Keep the character. Renew the sash. Upgrade the window.

Keeping the Window's Place in the Home

That distinction matters more than it sounds. Retaining the frame retains the window's established position and depth within the wall, the relationship between sill, reveals and architraves, and the exterior proportions that were part of the original design. From an architectural point of view it is a proportionate intervention: existing joinery and established relationships are kept, while the glazed and working elements are renewed. For architects and designers working on character housing, that distinction is often what separates an upgrade that reads as original from one that quietly announces itself from the street. Inside, the timber the family has lived with, the sill someone has repainted three times, the architrave with the pencil marks, stays in the room.

Designed Around Double Glazing

Original sashes were made for a single pane of glass. Their timber sections, rebates and drainage were sized for that, not for a sealed insulating unit with its own thickness, weight and moisture-management requirements. Suitable existing sashes can often be adapted successfully, and many are. But building a new sash creates the opportunity to design every element around double glazing from the beginning: the timber sections, the glazing space, the seals, the drainage and ventilation paths, and the hardware sized for the finished weight.

The established RetroGlaze timber retrofit process adapts suitable existing timber sashes and can achieve an excellent result. It remains the right answer on a great many projects, and Escence Wood does not replace it. What Escence Wood adds is a second considered pathway for homeowners who want a newly engineered sash while keeping their existing frames, and who would rather specify that component in advance than adapt one. In practice, the pathway is best decided project by project rather than sash by sash, so that a whole elevation stays visually consistent and the installation runs as one coordinated exercise.

More than a Replacement Piece of Joinery

An Escence Wood sash is not a double-glazing unit set into new timber. It is a system in which each part is specified against the others. The sash profiles are engineered from New Zealand-grown radiata pine: thermally modified, laminated, H3.1 treated, and factory alkyd-sealed, so stability and durability are designed in rather than hoped for. Timber weather-seal profiles and compression seals manage the junction between the new sash and the retained frame, and that junction is where draughts and water ingress are usually decided. Specified glazing, drainage and ventilation details keep moisture moving out of the sash rather than sitting in it. Operating hardware is specified by your RetroGlaze Partner and chosen with you, so the look suits the house and the window still closes onto its seals properly after years of use. Internally, classic bevel-shaped and ogee curved-shaped glazing bead profiles allow the new sash to sit comfortably alongside the period detailing already in the room.

Escence Wood has been developed and tested as a complete sash system rather than as a piece of glass, because comfort and weathertightness in a window are produced by the way the sash, glass, seals, hardware, retained frame and installation work together. Casement, split-rail (awning) and fixed configurations have been independently tested to the WGANZ 502 Field Test up to Extreme Wind Load. As with any tested building system, performance in a particular home depends on the sash configuration and size, the glass, seals and hardware specified, the condition of the retained frame, and the installation.

A More Planned Renovation Process

The installation itself is straightforward to describe. The existing fixed or opening sash is removed. The retained frame is checked and prepared. The purpose-made Escence Wood sash is installed. The new hardware and weather-seal system complete the window.

What sits behind that sequence is the useful part. The sash is manufactured, treated, sealed and, in most cases, glazed before the installer arrives, so much of the work that would otherwise happen at the property has already been done. Where site conditions make it the better option, glazing can be completed on site instead. That can reduce the renovation labour associated with modifying and reglazing each original sash, makes the on-site programme more predictable, and helps limit how long any individual room is affected. It will not make the process completely dust-free or a renovation effortless. But for homeowners who have put off enquiring because they imagine significant disruption, the shape of the job is more contained than expected.

There is a second kind of certainty here. Adapting an original sash sometimes reveals deterioration that only becomes visible once the sash is removed, stripped or machined, and that discovery can change both the programme and the cost. Because the new sash is purpose-made before installation, there is less dependence on what may be discovered inside an original sash once work begins. The retained frame still needs to be assessed, and may still require preparation or localised repair, but the sash component of the upgrade can be specified and prepared in advance.

Finding the Right Pathway for Your Project

Whether your frames suit Escence Wood is confirmed by a straightforward site assessment rather than by guesswork. Your local RetroGlaze Partner carries this out. Most sound timber frames are worth assessing. Where a frame is structurally unsuitable, or where the opening itself needs substantial redesign, complete window replacement may simply be the better answer.

Timber retrofit double glazing, Escence Wood sash replacement and complete window replacement each have their place, and a local RetroGlaze Partner can weigh them against the things that actually decide it: the condition of the frames, the architectural objectives, the site's exposure, how you want the windows to operate, the performance you are after, visual consistency across the elevations, and the scope of work you want to take on.

It is worth returning to where this started. Much of what makes an original timber window worth keeping is already held in the frame, the sill, the reveals, the architraves and the proportions that have been part of the house since it was built. Those things can stay. What can change is the part that was never designed for modern double glazing.

Explore the options for your timber windows by reaching out to us today. A local RetroGlaze Partner can assess the existing frames and recommend the most suitable upgrade pathway for the project.

Escence Wood™ is part of the RetroGlaze offering and is installed through participating local RetroGlaze Partners.