Flat roof extensions across Johnstone
A flat roof extension in Johnstone starts with the right design and the right approval route. We take care of both, then build it with our own project management.
- Guide price in JohnstoneFrom £20,500 inc VAT
- PlanningScottish householder rules; building warrant needed
- Build time10–16 weeks on site
- Postcode districtsPA5, PA10
Covering Johnstone
We cover Johnstone and the postcode districts PA5, PA10. The same team covers Paisley (3 miles), Barrhead (5 miles), Erskine (6 miles), Renfrew (6 miles), all within easy reach.
Clydebank, in Dunbartonshire, is roughly 7 miles from Johnstone and also on our list. Across Scotland, extensions follow Scottish planning and building standards, including the building warrant process, which we build into the programme from the start.
What should I budget for a flat roof extension in Johnstone?
These guide figures apply our Scotland adjustment (×0.98) to national rates. They include VAT at 20% and cover the build itself; design and council fees are listed separately.
Typical rates in Johnstone: £1,720 to £3,280 per m² including VAT, depending on specification.
| Size | Essential | Standard | Premium |
|---|---|---|---|
| 3 m × 4 m 12 m² | £20,500 – £24,500 | £24,000 – £31,000 | £30,500 – £39,500 |
| 4 m × 5 m 20 m² | £34,000 – £40,500 | £40,000 – £51,000 | £50,500 – £66,000 |
| 5 m × 6 m 30 m² | £51,000 – £60,500 | £60,000 – £76,500 | £76,000 – £98,500 |
Try the guide-price tool to see a range for your own size and finish.
What we take care of
- Membrane choice: single-ply, EPDM or GRP
- Parapets or edge trims and flashings to the house
- Falls and outlets designed to drain properly
- Lanterns or rooflights with upstands
Planning rules that apply in Johnstone
In Scotland, householder permitted development rules (Class 1A for single-storey ground-floor extensions and Class 1B for extensions of more than one storey) allow some smaller extensions without a planning application, within limits on depth, height and distance from the boundary. Conservation areas and listed buildings are more restricted. Separately, almost every extension needs a building warrant from the council before work starts.
The planning position for a specific Johnstone address depends on its history and any designations, which is why we check it at the first visit.
Scotland has no Party Wall Act. Where work affects a shared wall or a neighbour's land, we agree access, protection and making good with your neighbour in writing before work starts.
Building close to a public sewer needs the agreement of Scottish Water, which we check during design.
Applications are decided by your council as planning authority.
What happens next
Site visits are free and there is no obligation. Where drawings are needed, the design stage is priced in writing before it starts.
Free site visit
It starts with a visit to your house to measure, check access and talk through ideas and budget.
Design and approvals
We draw the design, agree it with you and handle planning or permitted development checks and building regulations.
Fixed written price
With the design and specification agreed, you get a fixed written price and a start date.
Build and sign-off
Work is carried out to the agreed programme, inspected by building control and signed off at the end.
Common questions in Johnstone
Do I need building regulations approval in Johnstone?
Yes. Almost every extension needs it, whatever the planning route. In Scotland that means a building warrant before work starts.
Will my neighbours in Johnstone be involved?
If a planning application is needed, the council notifies neighbours. Where work is close to a shared boundary, we agree access and protection with them in writing.
How long does a flat roof extension take to build in Johnstone?
On site, typically 10 to 16 weeks once approvals are in place. Before that, allow 4–12 weeks design and approvals.
Can I walk on a flat roof extension?
Only for maintenance unless it is designed as a terrace. A roof terrace or balcony needs planning permission and a different structure.
Are flat roof extensions cheaper?
Usually slightly, because there is less roof structure and no tiles. Our guide range is about £1,720 to £3,280 per m² including VAT.
Book a free site visit in Johnstone
We will measure up, check the planning position and give you honest guide figures.
- Free, no-obligation site visit
- Planning route checked before you spend on drawings
- Written price once the design is agreed
- Building control sign-off at the end
Prefer to talk? Call 0800 088 6341 or .
Book a free site visit
Tell us a little about the project and we will arrange a time.