Blinds, fly screens and handles: planning around new double glazing

Why window coverings belong in the window plan

Window coverings are usually treated as a separate job that happens after the builders leave. With double glazing that can cause trouble, because the new window can change the space the covering was designed for. A blind that fitted neatly inside the old reveal may now hit a winder handle. A shutter that folded back against the frame may now clash with a sash that opens inward. A fly screen that clipped onto the old slider may not suit the new one.

These conflicts are easier to investigate before the windows are ordered, while the frame, hardware and covering choices can still be coordinated. After installation they are more awkward, and sometimes the only fix is new brackets, a different blind or a screen that works less well. This guide covers what to check, and the order in which the window supplier and the blind or screen supplier should do their measuring.

The information here is about coordination and fit. We do not cover blind fabrics, shading performance or security screens, which are specialist products with their own suppliers. If you are considering any of those, ask that supplier to talk to the window installer about the frame they will be fixing to.

Reveal depth and where the new frame sits

The reveal is the lining around the inside of the window opening, between the frame and the room. Its depth decides how much room there is for a blind, a shutter or a screen to sit inside the opening rather than on the wall.

A replacement window does not always sit in exactly the same position in the wall as the one it replaces. The new frame may be deeper or shallower, or set further in or out, depending on the product and how it is flashed and sealed. That can make the reveal deeper or shallower than before, sometimes by enough to matter for a blind that was already a tight fit.

A retrofit that keeps the existing frame usually changes less, but not nothing. A double glazed unit is thicker than a single pane, and some retrofit systems use modified sashes or glazing beads that sit further into the room. If a blind currently sits very close to the glass, ask whether the retrofit will reduce that gap.

The practical step is to ask the supplier at the measure where the new frame and sash will sit in relation to the current inside face of the reveal. If they expect a change, write it down against that opening so the blind supplier knows later.

Keeping existing blinds

Roller, Venetian and Roman blinds are the coverings most often kept. Each has a slightly different relationship with the window. Roller blinds hang flat and close to the glass when mounted inside the reveal. Venetian slats need clearance to tilt. Roman blinds stack into folds at the top and can project further into the room than people expect.

For each blind you want to keep, note three things before the measure: whether it is fixed inside the reveal or on the wall above the opening, how far the fabric or slats sit from the glass, and whether anything on the old window already touches it. Take a photo of the brackets. Those details let the window supplier warn you if the new frame or its handles will get in the way.

Blinds fixed on the wall above the opening, outside the reveal, are the least affected by a window change because they hang clear of the frame. If an inside mounted blind will no longer fit, moving it outside the reveal may be an option, but an inside-fit blind can be too narrow to cover the opening with useful overlap. Check its actual width, bracket positions and night-time light gaps before planning to reuse it.

The brackets themselves may need to come down while the window is replaced. Ask whether the installer removes and refits them, or whether that is left to you or the blind supplier. Put that responsibility on the quote so both trades know who is returning to complete it. Refitting must also preserve cord safety: the ACCC window-covering guide explains why unsecured cords are dangerous. Have suitable safety fittings checked during refitting, and obtain approval before drilling into a new window frame.

Shutters, curtain tracks and pelmets

Hinged shutters fixed inside the reveal swing open into the room and fold against the side of the opening. They need clearance from the window handle when folded back, and they must not block a sash that opens inward. If you plan a tilt and turn window, ask the shutter supplier whether their panels can clear the sash in both positions.

Curtain tracks and rods are usually mounted on the wall or ceiling and are the easiest coverings to keep. The main thing to check is that the curtain can hang clear of any projecting handle or winder, and that it will not trap an outward opening window's chain winder when drawn.

Pelmets and boxed heads above windows are sometimes disturbed when architraves come off. If a pelmet matters to you, mention it at the measure so the installer can plan around it or include refitting in the quote.

Handles, winders and locks

Almost every opening window has something that projects into the room: a lever handle, a winder, a lock or a cam fastener. On old aluminium sliders the catch is often small and flat. On a new awning window the winder handle may sit at the sill and project further. On a tilt and turn window the handle is typically on the side of the sash, at mid height.

Those positions decide where blinds and shutters can go. A roller blind that drops right down to the sill will sit on top of a sill mounted winder. A Venetian mounted close to the glass may snag on a side handle. Some hardware ranges offer folding or low profile winders that reduce the problem, so ask what options come with the frame being quoted.

Think about use as well as fit. A blind that has to be raised every time you open the window gets tiresome. If you will open a window daily, choose a covering and hardware combination that lets you reach the handle with the blind down, or at least partly down.

The opening style has the largest effect on all of this. The guide to choosing opening styles room by room explains which styles need space inside the room and which need space outside.

Fly screens and which side of the glass they go

Screens have to sit on the side of the window that the sash does not swing through. For windows that open outward, such as awnings and casements, the screen normally goes on the inside, and you operate the winder or handle through or around it. For windows that open inward, the screen normally goes on the outside. Sliders usually take a screen on the outside over the opening sash.

That placement affects blinds. An inside screen on an awning window takes up part of the reveal, leaving less room for a blind. Where both are wanted, ask whether the screen can be fixed flat to the frame and whether the blind should then be moved outside the reveal.

Screen types vary. Fixed screens stay in place, hinged or sliding screens open for access, and retractable screens roll away when not needed. Each takes a different amount of space and suits different opening styles. Check on the quote whether screens are included for each opening and what type they are, because some suppliers list them as optional extras.

Sliding doors often have a separate screen door. If you are replacing a sliding door, ask whether the new frame includes a track for a screen door, and whether your existing screen door will fit it.

Can existing fly screens be reused?

Old screens are usually made to fit a particular frame, so whether they can be reused depends on the type of work. With a full frame replacement, the old screens rarely fit the new frame, because the screen tracks, clips and dimensions are different. With a retrofit that keeps the existing frame, a screen that sits on the outside of a slider may still fit, provided the new sash and glazing beads do not get in its way.

Before the measure, check the condition of each screen. Torn mesh, bent frames and missing clips are worth replacing anyway, and it is simpler to include new screens in the window order than to arrange them separately later. If you want to keep particular screens, tell the supplier and ask them to confirm at the measure whether they will fit.

Screens made for the new window are usually matched to the frame colour. If you are keeping some old screens and getting new ones for other windows, consider how the mix will look from outside, especially on the front of the house.

Who measures when, and how to hand over the details

A sensible sequence is simple. First, before the window measure, decide which coverings stay and gather your photos and notes. Second, at the window measure, walk the installer through each covering and ask how the new frame, sash and handle will relate to it. Third, after installation, have any new blinds or shutters measured to the finished opening.

Measuring new blinds before the windows are installed is a common mistake. The finished reveal depth and handle positions are not certain until the windows are in, so a blind measured to the old window can end up the wrong size or clash with the new hardware.

Keep the window supplier's notes about frame position and hardware for each opening, and pass them to the blind or shutter supplier. If both trades are working in the same week, ask them to speak directly, which saves you relaying technical details you may not be sure about.

Hypothetical example: a bedroom with a blind worth keeping

A bedroom has a single glazed slider with a blockout roller blind mounted inside the reveal, very close to the glass. The owner wants a double glazed awning window instead of the slider and would like to keep the blind.

At the measure, the installer points out that the awning will have a winder at the sill and an inside fly screen. With both inside the reveal, the blind can no longer drop to the sill without sitting on the winder. The options discussed are moving the blind outside the reveal, choosing a folding winder handle, or keeping a slider for that room. The blind supplier checks that its width will cover the opening adequately in the proposed outside position and confirms suitable brackets and cord-safety fittings. The owner then chooses that arrangement, with the refitting responsibility recorded on the quote.