Flush Sash Window Services in Southeast England

Flush sash windows are designed so that the sash sits perfectly flush within the outer frame, creating a sleek, seamless appearance. They replicate the look of traditional timber windows while delivering the thermal efficiency, security and low maintenance of modern uPVC or aluminium systems.

Flush sash windows are ideal if you want a heritage or contemporary finish. They combine the timeless charm of period properties with the performance benefits of modern windows. They’re especially popular in conservation areas where authentic sightlines are important but energy efficiency cannot be compromised.

Yes — our flush sash windows can achieve excellent U-values with A-rated double or triple glazing, low-E coatings, and warm-edge spacers. They reduce heat loss, improve insulation and meet the latest Building Regulations, helping to lower energy bills and increase comfort year-round.

No — unlike traditional timber frames, modern flush sash windows in uPVC or aluminium are virtually maintenance-free. They won’t rot, flake or warp and only need occasional cleaning to stay looking new for decades.

Yes — security is standard. Flush sash windows are built with multi-point locking, reinforced frames and optional laminated or toughened glass. Many of our installations are PAS 24 compliant and can meet Secured by Design standards for added reassurance.

Absolutely. Choose from a wide range of colours, foiled finishes, woodgrain effects, decorative glazing and hardware. Dual-colour options (different inside and outside) are also available, allowing you to match both your interior décor and external façade.

Yes — flush sash windows are often accepted in conservation areas because their design closely mirrors original timber windows. They provide the heritage look required while still offering the performance benefits of modern glazing. We’ll advise you during the survey if permissions are required.

Pricing depends on size, style, glazing and finish. Flush sash windows are generally a premium upgrade over standard casement windows due to their refined detailing. We provide a free, no-obligation quote with transparent pricing and finance options (subject to status).

Yes — all installations come with a 10-year insurance-backed guarantee, plus manufacturer warranties on profiles, glazing and hardware. Installations are also FENSA-registered, and you’ll receive a compliance certificate for peace of mind and property resale value.

Most replacements do not require planning permission, but rules vary if your home is a listed building or in a conservation area. If you’re altering window sizes or styles, consent may be needed. We’ll guide you through the process if planning approval is required.

Installation time depends on the number of windows, property size and access. As a guide, a typical flush sash window installation is completed in 1–3 days for a standard home. We’ll confirm exact timelines during your survey and quotation process.

We supply and install flush sash windows across Hampshire, West Sussex, East Sussex, Surrey, Berkshire and parts of Kent & Greater London. See our Areas We Cover page or Request a Quote to confirm availability in your area.

Simply call 0800 368 9166, message us on WhatsApp 07932 960284, email sales@instantwindowsanddoors.co.uk or complete the Request a Quote form. We’ll arrange a free survey and provide expert recommendations tailored to your property.