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Expanded Polystyrene Flat Roof Insulation


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high performance insulation


KORE Inverted Flat Roof Insulation 3D Detail

What is KORE Inverted Flat Roof?

KORE Inverted Flat Roof is a high performance profiled insulation board (EPS200 & EPS300) that can be used in conjunction with an inverted flat roof system. The product consists of rigid boards cut from moulded blocks of EPS.

KORE Inverted Flat Roof insulation boards are produced using White EPS and are available in a range of thicknesses utilising high density EPS200 and EPS300. Due to the high compressive strength of the board, the KORE Inverted Flat Roof product line offers very low water absorption properties, making it the ideal solution for flat roof applications.

KORE Inverted Flat Roof is suitable for use on inverted flat roofs or zero pitched untrafficked roofs, balconies and terraced roofs subject to pedestrian access only, with a gravel ballast or paved finish on a suitably designed timber, concrete or metal structural deck and appropriate fully supported waterproofing system. KORE Inverted Flat Roof boards are also suitable for use with a green roof finish.

The Benefits of KORE Inverted Flat Roof

There are a number of benefits when choosing KORE Inverted Flat Roof:

  • Meets & exceeds building regulations. A U-value of 0.19W/m2K can be achieved with 160mm KORE EPS200 White.
  • It’s lightweight, quick and easy to install
  • Overlapping insulation boards prevent thermal bridges
  • Shiplapped boards prevent cold bridges by reducing air gaps in plane element
  • Low water absorption protects against freezing
  • Suitable for use on flat roofs with zero pitch and slopes up to 10 degrees
  • Suitable for both residential and commercial
  • Suitable for green roof construction


apartment building with green flat roof

Request a Quote

Submit your plans and receive a free, no obligation quotation for KORE Inverted Flat Roof Insulation specific to your project requirements.

KORE Inverted Flat Roof Technical Information

The image to the left is an example of KORE Inverted Flat Roof Insulation in an inverted flat roof application along with KORE Fill Cavity Wall Insulation in the exterior wall. KORE EPS for flat roofs can be used for a wide range of applications, including standard flat roofs, profiled sheet roofing cut to fall roofing and sarking roof insulation. For more information about additional applications please contact our technical team.

Physical Properties of KORE EPS Inverted Roof Boards




Reaction to fire

Class E

Class E

Thermal conductivity



Minimum compressive strength at 10% compression (kPa)

CS (10) 200

CS (10) 300

Minimum bending strength



Water vapour diffusion factor

40 to 100

40 to 100

Long term water absorption by partial immersion

WL(P)i 0.2kg/m²

WL(P)i 0.1kg/m²





5mm difference between diagonals

5mm difference between diagonals

Dimensions of KORE EPS Inverted Flat Roof Boards

Board Type

Type 1

Type 2

Surface Length (mm)

Standard 1200mm (can be cut to other sizes up to 1800mm)

Standard 1200mm

Surface Width (mm)

Standard 1200mm

Standard 1200mm

Full Board Size ( L x W)

1200mm x 1220mm

1220mm x 1220mm

Thicknesses (mm)

100, 150, 200, 250, 300 (other thicknesses available upon request)

100, 150, 200, 250, 300 (other thicknesses available upon request)

Lap Joined Edge



Board Type 1 – Shiplapped 2 sides

KORE Flat Roof Insulation Shiplapped Board 2 sides

Board Type 2 – Shiplapped 4 sides

KORE Flat Roof Insulation Shiplapped on 4 Sides

Get Started with KORE Inverted Flat Roof

Want to learn more about the KORE Flat Roof Insulation product range? Request a quotation and speak with our technical department today to learn more about his high performance, cost effective solution.

Request a quote

Other KORE Flat Roof Applications

KORE Flat Roof Insulation Boards can be used for a wide variety of flat roof applications. KORE Flat Roof is normally supplied as a component to an approved system, but can be profiled for specific applications where only EPS is required. KORE Flat Roof applications include but are not limited to:

  • Standard flat roof applications
  • Inverted flat roof applications
  • Warm flat roof applications
  • Tapered roof applications
  • Profiled sheet roofing for new build or retrofit applications
  • Cut to fall tapered roof insulation

More information on the above products will be made available in the near future.

residential building with flat roof insulation
published:13 Nov 2020