Monmouth at a glance
- Postcode districts
- NP25
- Population
- about 10,110 (GeoNames)
- Council area
- Monmouthshire County Council
- Building approval
- Monmouthshire County Council building control, or a registered building control approver
- Nearest main town
- Abergavenny, about 13 miles
- Guide price region
- Wales (−8% on West Midlands rates)
Why choose a green roof in Monmouth?
Homeowners in Monmouth building a new extension may find a green roof can help with a planning application, as some councils encourage them for biodiversity and slower rainwater run-off. It is worth raising early with your designer, before the roof structure is drawn up, so the joists can be sized for the extra weight.
Around Monmouth, flat roofs are common on 1930s semis with flat-roofed garages and kitchen extensions and on 1960s and 1970s link-detached houses with flat-roofed garages and porches. Wales averages roughly 1,460 mm of rain a year, among the wettest in Britain, so we design for steady run-off: proper falls, clear outlets and upstands well above the finished roof.
How much does a green roof cost in Monmouth?
For Monmouth we use Wales rates: £4,050–£7,450 is the guide for a 20 m² insulated extension roof finished as a sedum green roof, VAT included. The fixed price comes after a free survey for new and replacement roofs.
| Job | Guide price inc VAT |
|---|---|
| Extension (20 m²), EPDM with sedum green roof | £4,050–£7,450 |
| Extension (20 m²), EPDM, new deck + insulation | £2,600–£4,500 |
Can my flat roof take the weight of a green roof?
Not every roof can, which is why we check the structure before quoting. A sedum roof is light compared with an intensive garden, but its growing medium holds water, and a saturated build-up adds significant weight to the roof.
We look at the joist sizes, spans and spacing, the condition of the deck and what the roof sits on. On a recently built extension with generously sized joists, an extensive green roof may be straightforward. On an older garage or a roof with undersized or rotten timbers, the structure may need strengthening, or a structural engineer's calculation may be needed before we can go ahead.
In England, a new roof covering that adds 15% or more to the weight of the roof triggers building control approval, and a green roof will often fall into that category. We handle building control where it is needed. The building regulations page covers the approval routes in each nation.
What's included?
- Root-resistant membrane or separate root barrier
- Warm or inverted build-up to suit the roof
- Structural check of joists, deck and supports
- Pre-grown sedum blankets laid and watered in
Building regulations in Wales
The Welsh Approved Document L applies. Renovating more than half of a roof over a heated room means upgrading it to around 0.16 W/m²K where feasible, and new extension roofs are built to 0.13 W/m²K. Welsh Government guidance is that most re-roofing needs building control approval, so check whenever more than a quarter of a roof is replaced or repaired. We deal with the application as part of the job. More on the rules.
Which nearby areas do we also cover?
Green and sedum roofs in Monmouth: questions
Do you cover Monmouth?
Yes. Monmouth is part of our Monmouthshire coverage, including postcode districts NP25. Surveys and roofs are carried out by vetted roofing teams working under S&K Property Investments and Improvement Ltd.
Who checks building regulations for a flat roof in Monmouth?
Where the work needs approval it goes to Monmouthshire County Council building control, or a registered building control approver. 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 green roof cost in Monmouth?
£4,050–£7,450 for a 20 m² insulated extension roof finished as a sedum green roof, at Wales guide rates including VAT. The fixed price comes after a free survey for new and replacement roofs.
Can a green roof have a rooflight in it?
Yes. The rooflight sits on a raised upstand with a gravel strip around it, so the planting stays clear of the glazing and the upstand stays visible and dry.
Can you put a sedum roof on a garage?
Often, yes, if the structure is strong enough. Many older garage roofs have light timbers, so a structural check comes first and strengthening may be needed.