Build Your Replacement Double-Glazed Unit

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1200 mm 1400 mm
1.2 W/m²K
uPVC Frame
1.68 m²

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Cross-Section

Getting Started

What are you replacing and how big is it?

Installation Type
Frame Material
Dimensions
150 – 4000mm
150 – 4000mm
Area: 1.68 m²

Glass Selection

Choose your glass type and configuration

Glass Type
Unit Thickness

Performance & Upgrades

Fine-tune thermal performance and add optional upgrades

Core Specification

Performance Tier
Privacy Glass
Cavity Width
Spacer Bar Colour
Laminated Glass

Optional Upgrades

Mandatory for doors, skylights & overhead glazing

Reduces heat gain from direct sunlight

Improves U-value by ~0.15 W/m²K

Pilkington Activ coating — breaks down dirt with UV light

Design Options

Add cutouts, Georgian bars and other design extras

Design extras +£0
Add a reference photo (optional)

Click to upload or drag and drop
Up to 3 photos, max 10MB each

Photos help us get your order right first time

Review & Order

Check your configuration summary before ordering

Show price breakdown
Energy Savings Estimate

Energy Savings Estimate

Standard Double Glazing
2.80 W/m²K
C
Your Configuration
1.40 W/m²K
A
50% Heat loss reduction
£0 Est. annual saving
— Payback period

Based on average UK heating costs (4.2p/kWh gas) and 2,000 heating hours/year. Actual savings depend on property insulation and heating habits.

Technical Specifications
£200.00 inc. VAT
Step 1 of 5
From inc. VAT 7-14 business days
FENSA Registered 10-Year Warranty
Qty

How the configurator works

  1. Enter your dimensions. Use sight-size measurements taken from inside the frame rebate. Our measuring guide walks you through the four numbers you need.
  2. Pick your glass and performance. Choose double or triple glazing, glass thickness, low-E coating, gas fill (argon vs krypton), and any acoustic, safety, or privacy options.
  3. Review your spec and price. The configurator shows the U-value, acoustic rating, and total weight, plus a delivery estimate to your postcode.
  4. Order or save for later. Add to cart for instant order, or request a free quote if you'd like our team to confirm the spec before you pay.

What you'll need before you start

  • Sight-size width and height (mm) — measured edge-to-edge of the visible glass, not the frame opening.
  • Frame depth — affects whether 28 mm standard or slim cavities will fit.
  • Frame material — uPVC, aluminium, or timber. Determines compatible spacer types.
  • Glass type of the existing unit (if known) — clear, low-E, acoustic, or toughened. Helps the configurator default to a sensible like-for-like spec.

How we calculate your price

The price is built from four inputs: unit area (m²), glass and coating spec, performance options (gas fill, spacer, low-E grade), and delivery zone. There are no hidden surcharges — VAT is included, delivery is shown at checkout, and bulk discounts apply automatically from 10 units.

Lead times

SpecificationDispatchUK delivery
Standard double-glazed (clear, argon)5 working days1–2 working days
Performance double-glazed (low-E, A-rated)5–7 working days1–2 working days
Triple-glazed7 working days1–2 working days
Acoustic (Rw 38 dB+)7–10 working days1–2 working days
Toughened or laminated safety7–10 working days1–2 working days

Frequently asked questions

Can I configure a unit if I'm not sure of the exact size?
Pick "Quote rather than buy" at the end. We'll review the spec and ask for clarification on any measurement we'd want re-checked before manufacture.
How accurate do my measurements need to be?
Within ±1 mm of sight-size. Replacement double-glazed units are manufactured to your specified dimensions; if too small, the unit rattles in the rebate; if too large, it won't fit. Our measuring guide covers how to take a reliable measurement.
What's the difference between a quote and an order?
An order is paid for and goes into manufacture. A quote is free, holds the price for 30 days, and lets you confirm the spec by phone or email before paying.
Do you supply trade and self-build customers?
Yes. Trade accounts get net pricing, NET 30 terms, and bulk discounts. Apply for a trade account.
What if my window has an unusual shape (arched, triangular, shaped)?
Use the configurator for rectangular units. For shaped glass, send dimensions and a sketch via the contact form — we manufacture to template.
How long does the gas fill last?
Per BS EN 1279-3, leak rate is capped at 1% per year. A well-built unit typically retains 80–85% of its argon or krypton fill at the 20-year mark. Misted units (where the perimeter seal has failed) lose fill rapidly and need replacing.