What is a dormer loft conversion?
A dormer loft conversion adds a box-shaped structure to the rear roof slope, creating vertical walls and full headroom across most of the new room. It is the most common loft conversion in the UK because it works on terraced, semi-detached and detached houses.
How much does a dormer loft conversion cost in Helensburgh?
In Helensburgh, a dormer loft conversion typically costs £46,500–£66,000 for a typical rear dormer with en-suite, including VAT at 20% (standard rate). Building costs in Scotland are close to the UK average, so the figures for Helensburgh are close to our national guide. Design, structural calculations and council fees are extra.
| Size or type | Guide range |
|---|---|
| A typical rear dormer with en-suite | £46,500–£66,000 |
| Higher specification | £66,000–£82,500 |
What moves the price most:
- En-suite or bathroom
- Scaffolding and access
- Built-in storage and finishes
- Dormer size and roof structure
Your exact price depends on the survey and drawings. The guide price tool gives a quick range in the meantime.
Do you need planning permission for a dormer loft conversion in Helensburgh?
Here is how the rules work for a dormer loft conversion in Scotland. In Scotland a dormer is permitted development (Class 1D) only on a roof slope that does not face a road, at least 10 metres from the boundary it faces, no wider than half the roof at the eaves, set at least 0.3 metres from the roof edges and with no increase in ridge height. It is not permitted development in a conservation area, and a building warrant is needed for a loft conversion.
In Scotland a building warrant is needed before work starts on most extensions, loft conversions and conversions. It is issued by the council’s building standards service. When the work is finished, a completion certificate is submitted and accepted by the council after inspection.
We check this for your address before design work starts, so there are no surprises later.
What we handle
On a typical dormer loft conversion we handle:
- Dormer structure, roof covering and windows
- Measured survey and head-height check
- New staircase and fire-safe escape route
- Written agreement with neighbours on shared walls
- Steel beams and new floor joists
- Building control completion certificate
How long does it take?
Expect 6 to 9 weeks on site. Design and approvals come first and typically take 6 to 12 weeks, depending on the approval route.
Building in Helensburgh
In Scotland, bungalows and one-and-a-half-storey homes are common, so dormer conversions are a popular way to add bedrooms.
We work across Helensburgh and neighbouring areas such as Greenock, Dumbarton and Dunoon. Postcodes we cover in Helensburgh include G84.
How it works
- 01
Visit and measured survey
A free visit to understand the project, check access and take measurements.
- 02
Design and pricing
Design options, then a fixed quote based on the chosen drawings and specification.
- 03
Approvals in place
We handle planning, building control and neighbour notices before work starts.
- 04
Build and sign-off
We run the build to a written programme and hand over the completion certificate.
Questions about dormer loft conversions in Helensburgh
How long does a dormer loft conversion take in Helensburgh?
Typically 6 to 9 weeks on site. Design and approvals beforehand usually take 6 to 12 weeks.
What fire safety is required?
Building regulations require a safe escape route. Converting a two-storey house to three storeys usually means a protected stairway with fire doors to habitable rooms and mains-wired smoke alarms.
Do I need planning permission for a dormer loft conversion in Helensburgh?
In Scotland a dormer is permitted development (Class 1D) only on a roof slope that does not face a road, at least 10 metres from the boundary it faces, no wider than half the roof at the eaves, set at least 0.3 metres from the roof edges and with no increase in ridge height. It is not permitted development in a conservation area, and a building warrant is needed for a loft conversion.
Will I need to move out?
No. Most of the work is done from scaffolding and the roof. The new staircase is formed near the end, which causes a few days of disruption.
How much does a dormer loft conversion cost in Helensburgh?
In Helensburgh, a dormer loft conversion typically costs £46,500–£66,000 for a typical rear dormer with en-suite, including VAT at 20% (standard rate). Your fixed price depends on the survey and drawings.
How much head height do I need?
Ideally at least 2.2 metres from the top of the ceiling joists to the underside of the ridge. Less can still work with a dormer, but we check this at the survey.