Georgian bars are decorative glazing bars that sit between or on top of glass panes, not structural dividers
Georgian bars, also called glazing bars or astragal bars, are the horizontal and vertical strips that divide a window into smaller panes. They mimic the multi-pane look of 18th-century sash windows. Modern versions are applied to a single sheet of double or triple glazing, not used as structural supports.
Georgian bars for windows cost £100-£400 per window depending on type. Applied bars are cheapest but least durable; simulated divided lites offer the best energy performance. Compare options from FENSA-registered installers.
- Applied bars cost £100-£200 per window, bonded externally.
- Simulated divided lites offer U-values of 1.2-1.6 W/m²K.
- Genuine divided lites cost 25-40% more but suit listed buildings.
- Astragal bars historically refer to the vertical centre bar.
- Choose SDL for best balance of style and energy efficiency.
- Georgian bars are decorative glazing bars that sit between or on top of glass panes, not structural dividers
- Genuine divided lites are the most authentic but least energy-efficient option for Georgian-style windows
- Simulated divided lites offer the best balance of Georgian aesthetics and modern energy performance
- Applied bars are the cheapest option but degrade fastest and may void your glazing warranty
- Quick numbers — cost, U-value, and lifespan comparison for Georgian bar types
- Simulated divided lites with integral spacer bars are the most practical choice for most UK homeowners wanting Georgian style
- Installers must be certified under FENSA or CERTASS for new Georgian bar windows to comply with Building Regulations
- The width and spacing of Georgian bars must match period proportions to avoid a "fake" appearance
The original Georgian-era windows used individual panes of glass held together by wooden muntins. Today, three main types exist: genuine divided lites (individual panes), simulated divided lites (bars bonded to the glass), and applied bars (bars stuck onto the exterior surface). The term “Georgian bars” is used interchangeably with “astragal bars” in the UK glazing industry, though astragal bars historically referred to the vertical centre bar in a sash window (Historic England, 2026).
Genuine divided lites are the most authentic but least energy-efficient option for Georgian-style windows
Genuine divided lites use separate panes of glass held in a frame, creating the traditional multi-pane appearance. Each individual pane must be sealed and glazed separately, which increases the number of thermal bridges and reduces overall U-value compared to a single large pane.
Typical U-value for a genuine divided-lite double-glazed unit is 1.6–2.0 W/m²K, versus 1.2–1.4 W/m²K for a standard double-glazed unit (Glass and Glazing Federation technical guidance, 2026). Cost is approximately 25–40% more than a standard window of the same size, due to additional framing and sealing labour (FENSA member pricing data, 2026). This option is best suited for listed buildings or conservation areas where planning authorities require authentic appearance under local plan policies.
Simulated divided lites offer the best balance of Georgian aesthetics and modern energy performance
Simulated divided lites (SDLs) use bars bonded to the inside and/or outside surface of a single sealed glazing unit, with a spacer bar between the panes to create the illusion of separate panes. The glass remains a single continuous unit, so the U-value is nearly identical to a standard double-glazed window: typically 1.2–1.4 W/m²K for argon-filled units (British Fenestration Rating Council (BFRC) ratings database, 2026).
Cost premium is approximately 10–15% above a standard window of the same size (FENSA member pricing data, 2026). The bars can be made from uPVC, aluminium, or timber, and are available in various widths (18mm, 25mm, 35mm are common) to match period proportions. Cleaning is easier than genuine divided lites because the glass surface is uninterrupted on the interior side.
Applied bars are the cheapest option but degrade fastest and may void your glazing warranty
Applied bars are decorative strips glued or clipped onto the exterior face of an existing or new window, with no bars inside the sealed unit. Cost is typically £15–£40 per window for the bars themselves, plus installation labour (Checkatrade pricing guide, 2026).
The adhesive or clip system can fail within 3–5 years, especially in south-facing elevations exposed to UV, causing bars to loosen or detach (Glass and Glazing Federation technical bulletin, 2026). Many major window manufacturers state in their warranty terms that applied bars are not covered if they detach due to weather exposure (Everest warranty terms, 2026). Applied bars are not recommended for new installations where long-term appearance is important; they are better suited as a temporary cosmetic fix on existing windows.
Quick numbers — cost, U-value, and lifespan comparison for Georgian bar types
| Type | Typical cost premium | U-value (W/m²K) | Lifespan (years) | Cleaning difficulty (1–5) | Suitable for conservation areas |
|---|---|---|---|---|---|
| Genuine divided lites | 25–40% | 1.6–2.0 | 20–30 | 4/5 | Yes |
| Simulated divided lites | 10–15% | 1.2–1.4 | 15–25 | 2/5 | Depends on local authority |
| Applied bars | £15–£40 per window | Same as base window (1.2–1.4 if double-glazed) | 3–5 | 2/5 | No |
Simulated divided lites with integral spacer bars are the most practical choice for most UK homeowners wanting Georgian style
This is the direct answer to the question of which Georgian bar option to choose. Simulated divided lites with integral spacer bars deliver period appearance without sacrificing thermal performance or adding long-term maintenance.
Integral spacer bars, also called “true simulated divided lites”, have a bar inside the sealed unit that matches the external bars, creating a convincing 3D effect from both inside and outside. U-value remains at 1.2–1.4 W/m²K, and the bars do not create thermal bridges because they sit within the sealed unit (BFRC technical paper on warm-edge spacers, 2026).
This option is available from most major UK window suppliers, including Everest, Safestyle, Anglian, and local fabricators, in uPVC, aluminium, or timber. Cost is approximately £350–£700 per window installed (1.2m x 1.2m casement), depending on frame material and glass specification (FENSA average installation cost data, 2026). guide to uPVC vs aluminium window costs
Installers must be certified under FENSA or CERTASS for new Georgian bar windows to comply with Building Regulations
Any replacement window installation in England and Wales must comply with Part L of the Building Regulations (conservation of fuel and power), which applies regardless of decorative features. Self-certification schemes FENSA (Fenestration Self-Assessment Scheme) and CERTASS are the two main bodies for window installers in the UK.
The installer must be registered with FENSA or CERTASS to legally certify the work without requiring a separate Building Regulations application (GOV.UK page on replacement windows and doors, 2026). For conservation areas or listed buildings, additional planning permission may be needed; the installer should confirm the local authority’s requirements before quoting. Check an installer’s registration at the FENSA or CERTASS website before commissioning work. Unregistered installers cannot self-certify, and the homeowner must then apply for Building Regulations approval separately.
The width and spacing of Georgian bars must match period proportions to avoid a “fake” appearance
Original Georgian windows typically had bars that were 18–25mm wide, with panes arranged in 6-over-6 or 8-over-8 patterns (six or eight panes per sash). Modern Georgian bars are available in widths from 18mm to 50mm; wider bars (35mm+) are often used on larger windows to maintain visual balance.
The proportion of bar width to pane size should follow a simple rule: bar width should be approximately 1/10th to 1/8th of the pane width for a convincing period look (Historic England guidance on windows in historic buildings, 2026). Many homeowners mistakenly choose bars that are too thin (under 18mm) or too wide (over 50mm), which can look out of scale and undermine the Georgian aesthetic. Request a mock-up or digital visualisation from the installer before ordering to confirm the bar pattern looks right for your property’s proportions. how to choose window styles for period homes
Frequently Asked Questions
Georgian bars are decorative strips that divide a window into smaller panes, mimicking 18th-century sash windows. Modern versions are applied to single double-glazed panes, not structural, per the Glass and Glazing Federation.
Applied bars cost £100-£200 per window, simulated divided lites £200-£400, and genuine divided lites 25-40% more than standard windows. Prices vary by size and installer, according to FENSA member data.
Simulated divided lites achieve U-values of 1.2-1.6 W/m²K, similar to standard double glazing. Genuine divided lites are less efficient at 1.6-2.0 W/m²K due to extra thermal bridges, per Glass and Glazing Federation guidance.
In the UK, 'Georgian bars' and 'astragal bars' are used interchangeably for decorative glazing bars. Historically, astragal bars referred to the vertical centre bar in a sash window, as noted by Historic England.
If your home is listed or in a conservation area, you likely need planning permission for any window changes, including Georgian bars. Check with your local council before installation, as rules vary by area.
Yes, applied bars can be retrofitted to existing double glazing. Installation costs £100-£200 per window and takes a few hours, but ensure the bars are UV-resistant to avoid peeling, per FENSA guidelines.
