RoofLogic UltraTherm Xtreme

Rooflogic Ultratherm Xtreme is a commercial membrane roofing solution that provides superior thermal and acoustic performance and extreme durability with the use of our Fibertite KEE membrane and Derbigum modified bitumen membrane.

Every component within the Ultratherm Xtreme system has been engineered to provide the highest levels of performance.

RL Base Deck is the only steel base deck that is tested in New Zealand for wind uplift, point load and fastener pull-out resistance.

RL PIR Board provides exceptional thermal performance right down to the elimination of thermal bridging through its tongue and groove construction.  It also offers improved impact resistance due to a high compressive strength twice that of most other PIR product in the New Zealand market.

When enhanced impact resistance/trafficability and acoustics is required Rooflogic specify a range of high density roof boards to meet the demands of your project.

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Designed/Engineered/Tested as a System

Rooflogic has carried out extensive system testing on the Ultratherm Xtreme system in New Zealand.  Ultratherm Xtreme is tested “as a system” for structural performance.  Structural calculations are provided for all Xtreme projects and a PS1 for design can be supplied.

Management of Condensation Risk

Many traditional roof assemblies fail to effectively manage vapour drive resulting in condensation occurring within the layers of the roof assembly (interstitial condensation.)  Condensation within a roof system will reduce thermal performance and result in mould growth and component corrosion.  The Rooflogic Ultratherm Xtreme system incorporates a complete vapour control layer that effectively separates the internal and external environment.  A properly detailed vapour control layer in conjunction with the required level of thermal performance will mitigate against the risk of condensation within the roof assembly.  Hygrothermal Calculations are provided for all Xtreme roof installations to establish the risk of condensation, mould and corrosion is mitigated.

Acoustic Performance

By adding or changing a range of system components the Rooflogic Xtreme system can be designed to achieve high levels of acoustic performance.  By introducing acoustic board layers, high density roof boards or by substituting RL PIR Board for RL Stone Wool the Ultratherm Xtreme system can achieve exceptional performance in respect to environmental and rain noise attenuation.


Rooflogic Ultratherm Xtreme systems use the highest quality roofing membranes to ensure that the system provides long term performance.  Rooflogic uses Fibertite KEE thermoplastic membranes and Derbigum modified bitumen membranes because of their superior durability and in service performance history (learn more about these membranes in ROOFING MEMBRANES).

Thermal Performance

RL PIR Board is used as the insulating core within the Ultratherm Xtreme system.  RL PIR Board is laid continuously over the base deck and is unbroken by the building structure maintaining a continuous layer of thermal insulation.  A range of PIR thicknesses are offered to achieve R-values ranging from R2.0 to R5.2.


As well as utilising the highest performing membranes, the durability of the Ultratherm Xtreme system can be further enhanced by specifying high density/high compressive strength roof boards.  These roof boards dramatically increase the trafficability/impact resistance of warm roof systems.

Fire Performance

The Rooflogic Ultratherm Xtreme system has been tested to establish fire performance.  The system achieves a Group 1-S rating.

Design Flexibility


The Rooflogic Ultratherm Xtreme system can be installed over a range of substrates including structural metal base decks, concrete and plywood.  There are a wide range of base decks available – perforated for internal noise reduction, coloured for internal aesthetics and deep sections for increased spanning ability.

Membrane Selection 

The choice of membranes (Fibertite and Derbigum) means the specifier can select the right membrane for the project.  Derbigum is a robust, long lasting membrane with an exceptional aesthetic.  Fibertite offers the highest level of weather-tightness with exceptional puncture resistance, weld strength, detailability and chemical resistance.


With a range of tapered products (RL PIR Board, RL Stone Wool and RL Tapered PIR) falls to outlets can be achieved where a new or existing substrate has no or insufficient fall.

Acoustic Performance

Depending on requirements high levels of thermal performance can be achieved in respect to STC, rain noise and NRC rating.

Thermal Performance

R-values can be varied from R2.00 to R5.20 depending on project requirements.

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derbigum concrete
Derbigum Ply

Xtreme with Derbigum Membrane

Xtreme with Derbigum Membrane on concrete substrate

Xtreme with Derbigum Membrane on plywood substrate

UltraTherm Xtreme Projects...