Victorian windows are the windows of houses built between about 1837 and 1901: mostly vertical sliding sashes with larger panes than Georgian ones, often two-over-two or one-over-one, with small projecting “horns” at the bottom of the upper sash, and frequently set in canted or square bay windows. If you are replacing them, the big decision is whether to stay with a sliding sash or switch to a casement designed to look like one. This page explains how to make that call, what details matter on a Victorian house, and where the rules tighten. For the window styles themselves, see our sash windows and bay windows pages.
What Victorian windows look like and why
Glass technology shaped Victorian windows. Historic England’s guidance on traditional windows explains that cheaper, stronger plate glass from the 1830s removed the need for many glazing bars, so panes grew larger. Because the heavier glass gave the sash less internal support, joiners added horns to strengthen the joint at the meeting rail. Later in the century the Queen Anne revival brought small panes back into fashion, particularly in the upper sash, and casements remained common on smaller houses and Arts and Crafts designs.
So “Victorian” does not mean one pattern. A London-style terrace, a Berkshire villa and a railway cottage in Surrey can all be Victorian with quite different windows. The best reference is always the originals on your house or its neighbours.
Sash or casement on a Victorian house?
Staying with a sliding sash
A sliding sash keeps the original way the window opens, the meeting rail in the right place and the overall look from the street. It is the natural choice for front elevations, for houses in conservation areas, and where the sash is part of what gives a terrace its character. Many modern sash windows tilt in for cleaning. See our sash windows page for the options we supply.
Switching to a casement
A casement window with a transom set at the height of the old meeting rail can look surprisingly close to a sash from a distance, and it usually costs less. It also seals well and opens wide for ventilation. The trade-off is that the opening vents sit in the frame rather than one sash in front of another, so the stepped look of a sash is lost. Casements work well on rear elevations, side extensions and Victorian houses where the windows have already been changed. Our casement windows page shows the styles.
How to decide
- Street elevation of an unaltered terrace: sash.
- Conservation area or Article 4 area: check with your council first; sash is usually expected.
- Rear and side elevations: casement is often fine and saves money.
- Bedrooms used for escape: check opening size whichever style you pick (see below).
The details that matter
Horns
Horns are the small decorative extensions at the bottom of the upper sash stiles. Many modern sash windows offer them as an option, and they are worth having on a Victorian elevation, as their absence is one of the first things that makes a replacement look modern. Match the horn shape to any surviving originals where possible.
Pane pattern
Two-over-two (one vertical bar in each sash) and one-over-one are typical of mid-Victorian houses. Later houses may have small panes in the top sash and a single pane below. Bars should be set out to match; see our Georgian windows page for how bars are applied to modern glass units.
Sightlines and the reveal
Victorian windows usually sat back in the brickwork, with a painted frame and stone or brick cill. We fit replacements in the same position to keep the depth of reveal and the shadow line, rather than pushing frames forward to the face of the wall.
Bay windows on Victorian houses
Many Victorian homes have canted bays with a sash in each face. Replacing the windows in an existing bay is different from building a new one: the Planning Portal notes that a new bay window is treated as an extension and may need permission. When replacing windows in a bay, we check whether the bay structure relies on the old frames to carry any load, and add support where needed before the old frames come out. Our bay windows page covers the structural side in more detail.
Rules to check before you order
- Planning. Windows of similar appearance are usually permitted development, but listed building consent applies to significant works on listed buildings, and Article 4 Directions can remove the right in conservation areas.
- Energy. Replacement windows must meet 1.4 W/m²K or band B under Approved Document L, with some flexibility where a building’s character must be kept.
- Fire escape. Councils such as Richmond explain that escape windows need an unobstructed opening of at least 0.33m², at least 450mm wide and high, with a cill no higher than 1100mm. A replacement should not be worse than the window it replaces. Sliding sashes need checking carefully, as only half the window opens.
We do not make timber windows. If your house is listed and the council requires timber, we will tell you so honestly; our secondary glazing may help you keep the originals and improve comfort.
Mistakes we see on Victorian houses
- Replacing two-over-two sashes with plain single-pane casements on a terrace where every neighbour still has sashes.
- Top-hung “fake sash” vents that open outwards over a path at head height.
- Bright white frames on a street where the originals were painted cream or off-white; see window colours.
- Losing trickle vents or ventilation in rooms that need it, especially in older solid-walled houses.
Care and upkeep
Modern sashes need a clean of the tracks and a check of the balances once or twice a year. Casements need the hinges and locking points lubricated annually. Clean frames with mild soapy water only.
Book a free survey
We supply UPVC windows on the Selecta Advance 70 system and fabricate aluminium windows from £400 at our Fifield workshop, with lead times from 10 days and a 10-year guarantee. We cover Berkshire, Buckinghamshire, Surrey, west Kent and north West Sussex. Call 01753 965 005 or ask for a quote and we will survey your Victorian windows and talk through sash or casement for each elevation.
Frequently asked questions
Should I replace Victorian sash windows with casements?
On the front of an unaltered terrace or in a conservation area, staying with a sash usually looks right and is more likely to be acceptable to the council. On rear and side elevations, a casement with a transom at meeting-rail height can look close to a sash, costs less and opens wide. Many owners mix the two.
What are sash horns and do I need them?
Horns are small extensions at the bottom of the upper sash stiles. Victorian joiners added them to strengthen the joint when heavier plate glass removed the need for glazing bars. On a replacement they are decorative, but on a Victorian front elevation they make a big difference to how authentic the window looks.
Do I need planning permission to replace windows in a Victorian bay?
Replacing windows in an existing bay with ones of similar appearance is usually permitted development, unless the house is listed or an Article 4 Direction applies. Building a new bay is treated as an extension and may need permission. Check with your local planning authority if you are in a conservation area.
Can Victorian-style windows meet modern energy rules?
Yes. Replacement windows in England need to reach a U-value of 1.4 W/m²K or Window Energy Rating band B. Modern double-glazed sash and casement windows with bars applied to a single sealed unit can achieve this. Approved Document L allows some flexibility where the character of a historic building must be kept.
Are sliding sash windows suitable as fire escape windows?
They can be, but only half the window opens, so the clear opening must be checked. Escape windows generally need at least 0.33m² unobstructed, at least 450mm wide and high, with the cill no more than 1100mm above the floor. A replacement must not be worse than the window it replaces.