Buyer's guide - heritage windows that pass the planner's e
Heritage windows are a specialist product. You need a look that reads as authentic from the street, paired with modern thermal performance that passes Building Regulations. Get either one wrong and the project slows. This short guide explains the choices and common traps.
Why heritage aluminium and not timber?
Traditional timber sash and casement windows look lovely on day one. By year three they need repainting. By year ten they often have rot at the cill. By year twenty many have warped enough that they stick. Heritage aluminium looks identical from the street thanks to the slim frame and bonded astragal bar, but it does not rot, does not warp and does not need repainting. The powder coated finish carries a 25-year life. No maintenance, no rot, no worry.
Astragal bar vs Georgian bar - the detail that matters
Planners and conservation officers know the difference between a cheap clipped-in Georgian bar and a real astragal bar. A clipped bar sits on the glass inside the window and looks plastic. An astragal bar is bonded to the outside of the glass and has a matching internal bar - so from any angle it looks like a real muntin dividing real glass panes. It also casts a proper shadow on the glass, which is what makes an old window feel old. We use astragal as standard on this range.
What bar layout do I need?
Georgian 6-over-6 is a top sash with 6 small panes over a bottom sash with 6 small panes - the classic Georgian town-house look. Victorian 2-over-2 is a simpler grid - two tall panes in each sash - popular from about 1860 onwards. Astragal with a single horizontal bar is an Edwardian detail. Critall is the industrial steel-window grid of 1920s to 1950s, full of small rectangular panes and now hugely fashionable on new builds. Send us a photo of what you have and we will match it.
Part L on a listed or conservation property
Part L still applies even on heritage properties. Replacement windows in most conservation buildings have to achieve 1.4 W/m²K or better. Our heritage aluminium achieves 1.2 W/m²K with the bar, so you are compliant every time. If your planning officer grants a single-glazed slim-unit exemption (sometimes used on Grade II* and Grade I buildings) we can also do slim-profile 10 mm argon-filled units that look like single glazing from outside.
Listed building consent - how we help
If your building is listed you will need listed building consent before replacing windows. We have guided more than a hundred homeowners through this. We will supply drawings, elevations, product brochures, U-value tables and glass specification sheets for your planning application. For conservation-area properties you usually do not need a separate consent but the council will still want to check the design. Same pack works.
Colours that suit period homes
Heritage Green (close to RAL 6009 Fir Green) is the most-requested heritage colour in the UK. Off-white (close to RAL 9010) suits Georgian town houses. Cream (RAL 9001) works on Cotswold cottages. Sage and Moss Green suit country homes. Jet Black suits Critall-style and industrial conversions. Anthracite is the flexible modern choice.
What about flush casement heritage?
A flush casement heritage window has the opening sash level with the outer frame, just like a period joinery window. It is the purest period look. We offer both stepped and flush heritage casements. Stepped suits strict conservation requirements where the planner wants the old drip-bar profile. Flush suits most other period homes and is slightly cheaper.
Matching doors
A heritage window elevation looks best with a matching heritage entrance door. Our panel door range includes traditional moulded designs with matching astragal-bar top lights and side lights. You can have the entire elevation in one colour and one bar style - the upgrade homeowners love most.
How to quote
Take a photo of each window as it stands today and message us on WhatsApp using the QR code or the green WhatsApp button in the quote form. Tell us how many windows, what bar layout you want, and your favourite colour. We come back with a written quote within 24 hours. If it is a listed property we can often visit and produce the consent-ready drawing pack in the same visit.
