How Long Does Double Glazing Installation Take? | Guide

How Long Does Double Glazing Installation Take?

Upgrading your home with new double-glazed windows is one of the most effective ways to lower energy bills, block out street noise, and improve property security. However, many homeowners worry about the disruption to their daily lives during the fitting process. Understanding the timeline of a professional double glazing installation helps you prepare and ensures a smooth, stress-free installation day.

Expert Reviewed by Marian Gheorghe, Head Window Fitter — Last reviewed: July 2026

The Golden Rule: Standard Window Installation Times

As a general guideline, a standard uPVC casement window replacement takes an experienced fitting team approximately 1.5 to 2 hours per opening. This includes the removal of the old frame, preparing the brickwork, fixing the new frame in place, adding thermal insulation, glazing the sealed unit, and applying internal trims and external weatherproofing silicone.

For a typical residential home requiring a complete upgrade (averaging 6 to 8 windows), the physical installation is usually completed in 1 to 2 working days.

Breakdown by Window and Door Type

Different window styles and structural configurations require different amounts of time to install correctly:

• uPVC Casement Windows: 1.5 to 2 hours. The simplest and quickest style to fit.
• Aluminium Casement Windows: 2 to 2.5 hours. Requires additional care to handle slim profiles and set gaskets.
• Vertical Sliding Sash Windows: 3 to 4 hours. These frames are heavier and require precise calibration of slide-and-tilt balances to operate smoothly.
• Bay Windows: 4 to 8 hours. Bay installations are structurally complex, often requiring temporary structural support (props) and exact corner-post alignments.
• Composite Entrance Doors: 3 to 4 hours. Heavy doorsets requiring precise squaring of the frame to ensure multi-point locks align perfectly.
• Aluminium Bifold Doors (3-4 panels): 6 to 8 hours. Bifold tracks must be leveled to millimetre-tolerances to prevent binding.

Step-by-Step Installation Day Timeline

Here is what a typical day looks like when our team arrives at your property:

1. 8:00 AM — Arrival and Preparation: Our team introduces themselves, sets up a work station, and lays down protective floor runners and dust sheets.
2. 8:30 AM — The Window-by-Window Method: To maintain security and minimize thermal loss, we work on one window at a time. We do not remove an old frame until the new replacement unit has been measured and verified.
3. 9:00 AM — Frame Removal: We carefully cut out the old frame and clear away old expanding foam, sealant, and debris from the brickwork opening.
4. 10:00 AM — Installing the New Frame: The new frame is positioned, leveled, and secured using heavy-duty masonry fixings. The perimeter cavity is packed with high-grade thermal insulation.
5. 11:00 AM — Glazing and Adjustments: The double-glazed units are fitted into the frame using glazing packers. Hinges, locks, and handles are adjusted.
6. 12:00 PM — Sealing & Handover: External weatherproofing silicone is applied, and internal trim is fitted. We vacuum the room, remove the old frames, and demonstrate lock operations.

What Factors Can Delay the Process?

While we strive to meet our estimated timelines, certain factors can occasionally extend the duration of the work:

• Hidden Structural Damage: If our installers discover rotten lintels, decaying brickwork, or missing structural supports behind old frames, we must stop and repair these issues to ensure safety.
• Inclement Weather: While light rain won't stop our team, heavy downpours or freezing temperatures can prevent external silicone sealants from bonding correctly to the brickwork.
• Complex High-Reach Access: Third-floor windows or difficult-to-reach angles may require scaffolding or specialized access platforms, extending setup and installation times.

About the Author: Marian Gheorghe

Head Window Fitter & Active Director, Window Fitters Ltd

Marian Gheorghe has over 15 years of on-site experience managing residential and commercial glazing installations in London. He oversees project scheduling, technical site preparation, and installer safety compliance.

Connect on LinkedIn → Expert Reviewed: July 2026

Glazing Installation FAQs

Do I need to leave the house during the installation?

No. You can stay in your home. Our team works room by room, cleaning as we go. We only ask that pets and small children are kept away from active work areas for safety.

Will my house be left cold or open overnight?

Never. We ensure every opening is fully fitted, sealed, and secured before our team leaves at the end of the working day. We do not leave holes in your walls overnight.

How can I prepare my home to speed up the fitters?

To help us work efficiently, please clear a 2-metre workspace in front of all windows, remove curtains, blinds, and nets, and clear any breakables from nearby sills and shelves.