Johnstone at a glance
- Postcode districts
- PA5
- Population
- about 15,930 (GeoNames)
- Council area
- Renfrewshire Council
- Building approval
- Renfrewshire Council building standards
- Nearest main town
- Paisley, about 3 miles
- Guide price region
- Scotland (−5% on West Midlands rates)
Why upgrade to a warm roof in Johnstone?
Landlords with flats and HMOs in Johnstone sometimes hear from tenants about cold top-floor rooms and black mould on ceilings. A warm roof upgrade during re-roofing tackles both the heat loss and the condensation behind the mould, and helps keep the roof timbers dry.
In a town like Johnstone, flat roofs are commonly found on shops with flat-roofed rear stores below flats or 1960s and 1970s link-detached houses with flat-roofed garages and porches. Scotland averages roughly 1,570 mm of rain a year, with the west far wetter than the east, so drainage, falls and wind uplift are part of every specification we write.
How much does a warm roof upgrade cost in Johnstone?
Guide price in Johnstone: £2,650–£4,650 for a 20 m² extension roof in EPDM with a new deck and insulation, including VAT at Scotland rates. The fixed price comes after a free survey for new and replacement roofs.
| Job | Guide price inc VAT |
|---|---|
| Extension (20 m²), EPDM, new deck + insulation | £2,650–£4,650 |
| Extension (20 m²), EPDM with sedum green roof | £4,200–£7,700 |
Can a cold flat roof be converted to a warm roof?
Yes, and it is the usual approach when an older cold roof is re-covered. The old covering is stripped, the deck is checked and replaced where needed, and the vapour control layer, insulation and new waterproofing go on top.
The existing insulation between the joists is assessed at the same time. Leaving it in place can create a cold, unventilated gap that traps moisture, so it is often removed or the build-up is designed so that most of the insulation sits above the deck. We decide this case by case once we can see inside the roof. If the covering is still sound and you are only patching it, the upgrade isn't usually required, and our repair or replace guide explains how to decide between the two.
What's included?
- Rigid insulation boards sized to the U-value target
- Upstands, trims and kerbs reset to the new roof level
- Building standards handled where needed
- Vapour control layer on the warm side of the insulation
Building standards in Scotland
In Scotland the building standards technical handbooks (Section 6 for energy) apply, and the council's building standards service decides whether a building warrant is needed. Like-for-like repairs to a roof covering can be exempt; alterations, structural work and new roofs usually need a warrant before work starts. The domestic roof benchmark is 0.12 W/m²K, applied as far as reasonably practicable on an existing roof. More on the rules.
Which nearby areas do we also cover?
Warm roof insulation upgrades in Johnstone: questions
Do you cover Johnstone?
Yes. Johnstone is part of our Renfrewshire coverage, including postcode districts PA5. Surveys and roofs are carried out by vetted roofing teams working under S&K Property Investments and Improvement Ltd.
Who checks building standards for a flat roof in Johnstone?
Where the work needs approval it goes to Renfrewshire Council building standards. We tell you at the survey whether your job needs it and deal with the paperwork as part of the quote.
How much does a warm roof upgrade cost in Johnstone?
£2,650–£4,650 for a 20 m² extension roof in EPDM with a new deck and insulation, at Scotland guide rates including VAT. The fixed price comes after a free survey for new and replacement roofs.
How thick does flat roof insulation need to be?
It depends on the insulation product and the U-value target. With common PIR boards, meeting a renovation target usually means well over 100 mm. Thinner, higher-performance boards are available where height is tight.
Can you add insulation over my existing roof without stripping it?
Sometimes, if the existing covering and deck are dry and sound. We will check at the survey and explain the risks, and our overlay or strip guide covers this choice.