01473 257671Contact usMembers Area
Inverted roof insulation

Inverted roof insulation

Thermal insulation layer located above the structural deck and waterproofing, widely used on heavily trafficked roofs and podiums.

Overview

In an inverted roof construction, the principal thermal insulation layer is located not only above the roof structure but also above the waterproofing, resulting in the waterproofing, structural deck and support structure being at a temperature close to that of the interior of the building. No vapour control layer is required.

Minimum levels of insulation required in flat roof constructions are governed by Building Regulations. These levels are rising on an ever-increasing scale as the Government strives to meet its targets for reducing CO2 emissions. 

We have different types of inverted insulation depending on your project's requirements and budget.

Read more about thermal design and condensation

Spotlight: Inverted insulation

Inverted roof insulation is robust. It has to be, it will be exposed to all weathers for the life of the building. It is also cost-effective and specified within a flat roof situation, especially for podium decks and plazas.

Let's take a look at inverted insulation and the properties and characteristics of these products.

Types of inverted insulation

Inverted insulations come in different types, expanded polystyrene (EPS), extruded polystyrene (XPS), cellar glass and vacuum insulation panels (VIP). Each have their own attributes to enable the specifier to meet the needs of the project. Your Bauder area technical manager will take you through the correct selection for your project taking into accounts budget, thicknesses and fire performance.

Moisture tolerant

Inverted insulation is exposed to moisture – unlike warm roof insulation that is encapsulated by waterproofing layers – and therefore needs to tolerate moisture, with any change in performance being accepted and accounted for by increasing the thickness of the insulation and incorporating a WFRL. 

Meeting BS 6229

Within the standard, clause 4.6.2.2 – Inverted Roofs, BS 6229 suggests that it is prudent to increase the design thickness of the thermal insulation of an inverted roof where a Water Flow Reducing Layer (WFRL) is being relied upon by “not less than 10%”. 

BBA and KIWA Certification

Within the standard, clause 4.6.2.2 – Inverted Roofs, BS 6229 suggests that it is prudent to increase the design thickness of the thermal insulation of an inverted roof where a Water Flow Reducing Layer (WFRL) is being relied upon by “not less than 10%”. 

Fire performance of inverted insulation

Bauder inverted insulation is specified in buried scenarios and are therefore fully covered with paving slabs, a green roof finish, pebble ballast etc and meet current Building Regulations without testing, with the exception of being used in the construction of a 'Specified Attachment'.

Water Flow Reducing Layer (WFRL)

The layer is loose-laid directly atop the inverted insulation to reduce the passage of rainwater to the waterproofed deck, enabling the greater part of drainage to take place at the WFRL level. The WFRL is resistant to liquid water but permeable to water vapour to allow any moisture vapour to disperse.

BauderVIP INV

BauderVIP INV

An inverted roof rigid vacuum insulation panel with a microporous core that is evacuated, encased, and sealed in a gas-tight membrane. BauderVIP INV panels are encapsulated in a protective polyurea coating for increased robustness and easier handling on site.

Spotlight: BauderVIP INV inverted insulation

BauderVIP INV inverted roof insulation has been designed to insulate those difficult roof areas that are hard to insulate with standard inverted insulations whilst being exposed to all weathers for the life of the building it is installed within. BauderVIP INV is at home in new build or refurbishment situations. Let's take a look at the properties and characteristics of this product.

Types of inverted insulation

Inverted insulations come in different compositions, expanded polystyrene (EPS), extruded polystyrene (XPS), cellular glass and Bauder’s latest addition, vacuum insulation panels (VIP). Each have their own attributes to enable the specifier to meet the needs of the project. Your Bauder area technical manager will take you through the correct selection for your project taking into accounts budget, thicknesses and fire performance.

Where to use?

BauderVIP INV panels are suitable for use where a lack of construction depth or space is an issue such as roof terraces over heated spaces and insulated walkways in an inverted roof build up. BauderVIP INV panels are suitable for use in both new build and refurbishment situations and are perfectly at home in hard, soft and blue roof environments.

Achieving thermal performance

BauderVIP INV has the best thermal performance of all of our inverted insulations. Good news for those roof areas that have a limited construction depth. A better thermal performance means thinner thicknesses are achievable. For example, to achieve a scheme containing BauderVIP INV can achieve a 0.16 u value in 100mm whereas our next best performer BauderJFRI PRMIUM+ needs 180mm.

Waterproofing compatibility

BauderVIP INV can be incorporated into inverted roof constructions when specifying our Bakor hot melt system, Bauder reinforced bitumen membranes and LiquiTEC cold applied waterproofing systems.

Fire performance of inverted insulation

Bauder inverted insulation is specified in buried scenarios and are therefore fully covered with paving slabs, a green roof finish (where appropriate), pebble ballast etc and meet current building regulations without testing, with the exception of being used in the construction of a 'specified attachment'.

Water Flow Reducing Layer (WFRL)

The WFRL is principally installed to reduce rainwater cooling. It is loose-laid directly atop the inverted insulation to reduce the passage of rainwater to the waterproofed deck, enabling the greater part of drainage to take place at the WFRL level. The WFRL is resistant to liquid water but permeable to water vapour allowing any moisture vapour to disperse.

Specification resources available in the technical centre

Contact us today about your project

Each project is unique in its requirements, and we have lots of resources and examples of our work available to help guide you. If you are looking for an inverted flat roof solution for your project, then get in touch with our team to discuss your project’s individual needs.