Group A · Loft and roof insulation
Inverted and green flat roofs
XPS insulation above the waterproofing under ballast, paving or a sedum roof.
Priced after survey
Inverted and green flat roofs
Every job like this is different, so we measure first and give you a fixed written quote. The price depends on:
- The area and access
- What's there now and its condition
- The system and finish you choose
No obligation — your survey confirms what suits and what it costs.
- Best for
- Roof terraces, balconies, commercial roofs
- Guarantee or standard
- System guarantee
- Time on site
- Most lofts are done in a day or less.
- Typical price
- Priced after survey
What it is
What is inverted and green flat roofs?
XPS insulation above the waterproofing under ballast, paving or a sedum roof.
Best for: Roof terraces, balconies, commercial roofs.
Build-up
Inverted roof
Outside
Inside
- 1Ballast, paving or sedum
- 2XPS insulation
- 3Waterproofing, protected underneath
- 4Roof deck
Who it suits
Which homes is inverted and green flat roofs suitable for?
Is my home suitable?
Pick your property type for a straight answer on inverted and green flat roofs.
Guidance only — every home is different, and a survey confirms what suits yours.
Houses
- Detached house
- Semi-detached house
- End-of-terrace
- Mid-terrace
- Townhouse
- Mews house and cottage
- Detached bungalow
- Semi and terraced bungalow
- Chalet and dormer bungalow
- Period home
- 1930s home
- Post-war and ex-council house
- Non-traditional / system-built
- Listed building or conservation area
- Farmhouse, barn conversion or rural home
- New build or self-build
Flats and blocks of flats
Commercial and public buildings
Usually suitable Depends — a survey confirms
Not usually suitable for 1 property type
- Park and mobile home — Park and mobile homes need specialist systems, which we arrange through a partner rather than standard measures.
Materials and brands
What we use
XPS insulation above the waterproofing, ballast, paving or green (sedum) roof build-ups.
Insulation brands we work with
- Knauf Insulation (Earthwool, Supafil blown)
- Rockwool
- Superglass
- Isover
- Kingspan
- Celotex
- Recticel
- Xtratherm
- Steico wood-fibre
- YBS and Actis multifoil
The exact system and brand for your home are confirmed in your written quote.
Heat, bills and EPC
What it does for your heat loss, bills and EPC
Heat rises, so a poorly insulated roof is often the largest single route out for heat. Insulating it lowers the roof's U-value — how easily heat passes through — so the heating runs less and the EPC rating usually improves. The gain is largest where there's little insulation now; topping up a loft that's already reasonably insulated gains less.
See the EPC points and savings for your home in the EPC plannerU-value before and after, typical heat and bill saving, and EPC points — worked out for your property.Price
How much does inverted and green flat roofs cost?
Priced after survey
Jobs like this vary too much for a fair online price, so we measure first and give you a fixed written quote — with no obligation.VAT on this work
Insulation installed in homes in Great Britain is zero-rated for VAT until 31 March 2027. Other parts of a job like this — such as a new roof covering, structural work or waterproofing — may be standard-rated. Your quote shows the split.What to expect
Time on site, disruption and approvals
Time on site
Most lofts are done in a day or less. Roof, flat roof and room-in-roof work takes longer and is confirmed at survey.
Disruption
Low — the work happens in the loft or roof space. We need clear access to the hatch, with stored items moved to one side.
Planning and building control
Loft insulation doesn't need planning permission or building control. Re-roofing, flat roof replacement and turning a roof space into a room must meet Building Regulations Part L, and we handle the notification.
Guarantee and standard
System guarantee. The guarantee and certification for your job are confirmed in writing in your quote.
60-second grant check
Could a grant help pay for it?
Grant eligibility checker
About 60 seconds · plain results: likely, possibly or not eligible
Before we start
What type of property is it?
Questions
Inverted and green flat roofs: your questions answered
What is an inverted roof?
A flat roof where the insulation goes above the waterproofing, held down by ballast, paving or a green roof. The waterproofing is protected from sun, frost and foot traffic.
Why is XPS used on inverted roofs?
XPS resists water and has the compressive strength to sit outside the waterproofing under paving or ballast.
Can you build a sedum green roof?
Yes, as part of an inverted or green roof build-up — once we've confirmed the structure can carry the extra weight.
Group A
More in loft and roof insulation
Loft insulation
Mineral wool laid between and across the joists to 270–300 mm so heat stays in the rooms below.
Loft insulation top-up
An extra cross-layer over existing insulation to reach the recommended 270 mm or more.
Blown loft insulation
Loose-fill insulation blown into awkward, shallow or low-headroom lofts that rolls can't reach.
Loft clearance and replacement
Old, damp or damaged insulation removed, the loft cleaned, then new mineral wool fitted.
Raised loft boarding and storage
Loft legs or raised boarding over full-depth insulation, so storage doesn't crush it.
Insulated loft hatch and ladders
An insulated, draught-sealed hatch and loft ladder — a small add-on that stops a big leak.
Begin your project
Ready to talk about inverted and green flat roofs?
Tell us about your home and we'll arrange a survey, then a fixed written quote — no obligation.