Ultimate Guides
The long-form references: complete buyer's guides, the full size chart and decoder, and the cost calculator.
Custom Skylights: The Ultimate UK Guide (2026) Every custom skylight option for UK homes — flat glass, lanterns, walk-on and structural glazing — with 2026 costs, materials advice and the regs. 
Estimate your skylight or roof window cost in 10 seconds — by type, size, powered opening, scaffolding and region. Built on 2026 UK trade-guide data.
Type any VELUX code — MK06, 304, C04, even 1970s GGL 1 — and get its exact dimensions and modern equivalent. Full size charts for every generation.