Question 1

Bifold vs sliding doors, which is better for a 4m opening?

Accepted Answer

Sliders give larger unobstructed glass panels with slim 20mm sightlines possible and better views when closed. Bifolds give full opening for summer entertaining but leave a bulky stack when closed. At 4m, a 3-pane sliding door is often preferred for daily use, while a bifold wins if you want the entire opening clear in summer.

Question 2

How much does a 3m bifold door cost fitted in London?

Accepted Answer

Aluminium 3m 3-pane bifold supply and fit typically costs £4,500-£7,500 in London depending on brand, threshold spec, and colour finish. Premium systems like Cortizo X-Fold 120, Schuco AS FD or Origin go up to £9,500. Heritage steel-look bifolds (Smart Aluspace) typically sit at the upper end.

Question 3

Do uPVC windows really last 20 years or do they go yellow?

Accepted Answer

Modern uPVC (post-2010) uses UV-stable compounds and typically lasts 25-30 years with minimal fade. The 1990s white uPVC discolouration problem is a legacy issue, contemporary Deceuninck, Liniar, and Smart Systems uPVC ranges carry 10-year colourfast guarantees on foiled finishes.

Question 4

Are roof lanterns better than Velux skylights?

Accepted Answer

Roof lanterns are for flat roofs and create architectural centrepieces. Korniche corner-key lanterns minimise sightlines to 38mm. Velux windows are for pitched roofs and are much cheaper but provide a smaller viewing area. They are not interchangeable, the choice depends on your roof construction.

Question 5

What's the most energy-efficient frame material?

Accepted Answer

uPVC has the lowest inherent thermal conductivity of mainstream frame materials, followed by timber. Aluminium needs polyamide thermal breaks to compete, modern thermally broken aluminium (like Cortizo Cor 70 Hidden Sash) achieves 0.84 W/m²K whole-window, matching premium uPVC. Heritage uPVC sits around 1.3 W/m²K due to deeper mouldings.

Question 6

Which London areas does Apex Glazing install in?

Accepted Answer

We install across West London and the South West, including Richmond, Twickenham, Isleworth, Kingston upon Thames, Teddington, Hampton, Chiswick, Kew, Barnes, Mortlake, Brentford, Hounslow, Ealing, Hammersmith, Fulham, Putney, Wimbledon, Sheen, Surbiton, and Weybridge.

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