Do Velux windows need planning permission?

Roof windows (including Velux) that do not project more than 150mm above the roof plane and are fitted in the existing roof are usually permitted development. Side elevation windows in conservation areas may need approval.

How long does a Velux window last?

Velux windows are designed to last 20–30 years. The sealed glazing unit may need replacing after 15–25 years if condensation appears between the panes. Velux offer a 10-year guarantee on new windows.

Can I fit a Velux window myself?

The window itself can be DIY-fitted if you are confident working at height and the roof structure is straightforward. However, the roof flashing (weatherproofing around the frame) is critical and often benefits from a skilled roofer to ensure a watertight installation.

Extensions & Conversions · Last updated 19 October 2026

Velux window cost

Typical range£600–£5,000· Average Velux window installed (78x98cm)

Velux and roof window installation prices for 2025. In the UK, expect to pay between £600 and £5,000, with the typical project around £1,100 (average velux window installed (78x98cm)). Regional variation, specification tier and site access conditions all shift the final quote.

Quick answer: Velux window cost in the UK typically costs between £600 and £5,000 (Average Velux window installed (78x98cm)). London and the South East run 20–35% above this range; the North, Wales and most of Scotland sit 5–15% below.

Homeowners researching this typically also price up double glazing cost. For wider context, browse our bathroom pricing, kitchen pricing and boiler & heating costs.

Cost table

Indicative price ranges (UK, GBP)

Item	Typical range (GBP)
Small Velux (55x78cm, supply & fit) — Entry size, one window	£600–£900
Standard Velux (78x98cm) — Most popular size	£900–£1,400
Large Velux (94x118cm) — More light, more expensive	£1,200–£2,000
Electric / remote Velux — Motorised, rain sensor, remote	£1,500–£3,000
Multiple windows (3 units) — Three standard Velux, loft conversion	£2,500–£5,000

Labour costs

Labour typically accounts for 40% of the total project cost in the UK.

Labour line items

Item	Typical range (GBP)
Roofer (per window)	£200–£450
Internal fitting / lining	£100–£300/window
Electrician (electric models)	£150–£300

Materials costs

Materials and fittings make up the remainder of the budget, with specification tier driving most of the variation.

Materials & fittings

Item	Typical range (GBP)
Velux GGL (manual, 78x98cm)	£350–£600
Velux GGU (white PVC, 78x98cm)	£400–£650
Velux GGL (electric, 78x98cm)	£700–£1,200
Flashing kit (included usually)	£60–£120
Internal reveal lining kit	£80–£200

Factors affecting cost in the UK

·Region — London and the South East run 15–30% above national averages.
·Specification tier — premium materials and finishes can double the base cost.
·Access and site conditions — flats, restricted parking and listed buildings add time.
·Scope changes mid-project — late design decisions are the biggest cost overrun driver.
·Trade availability — quotes rise 10–20% in peak spring and summer months.

Hidden & unexpected costs

·Cutting and trimming roof rafters to suit the window opening.
·Lining, plastering and decorating the internal reveal.
·Replacing roof tiles or slates around the new opening.
·Blinds, electric openers and rain sensors as add-ons.
·Building control sign-off for openings near boundaries.

Ways to reduce cost

·Choose standard sizes (CK04, MK06, UK04) rather than bespoke openings.
·Fit two smaller windows rather than one large for cheaper structural work.
·Buy direct from Velux distributors rather than through a roofing contractor.
·Phase install with a planned re-roof to share scaffold and roofer labour.
·Skip electric openers unless the window is genuinely out of reach.

Permission

Roof windows are usually permitted development if they do not project more than 150mm above the roof plane and are not higher than the highest part of the roof. Side-facing windows must be obscure-glazed and fixed shut unless the opening part is over 1.7m above the floor. Conservation areas and listed buildings may need consent.

Replacement vs new opening

Replacing an existing roof window of the same size is a quick job, often done from inside. Cutting a new opening means trimming rafters, which needs building regulations approval, and finishing the internal lining.

Escape windows in lofts

If the window serves a habitable loft room, building regulations may require it to meet escape-window size and position rules. Check this with your installer or building control before ordering.

Frequently asked questions

Do Velux windows need planning permission?: Roof windows (including Velux) that do not project more than 150mm above the roof plane and are fitted in the existing roof are usually permitted development. Side elevation windows in conservation areas may need approval.
How long does a Velux window last?: Velux windows are designed to last 20–30 years. The sealed glazing unit may need replacing after 15–25 years if condensation appears between the panes. Velux offer a 10-year guarantee on new windows.
Can I fit a Velux window myself?: The window itself can be DIY-fitted if you are confident working at height and the roof structure is straightforward. However, the roof flashing (weatherproofing around the frame) is critical and often benefits from a skilled roofer to ensure a watertight installation.

Sources & how we estimate

Prices are typical UK ranges compiled by ModernExpert.AI from published trade rates and supplier price lists, and are estimates — always get at least three written quotes. Rules on permissions, safety and certification come from the official sources below. Last reviewed 19 October 2026.

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