Ostro Passivhaus

Bauder Total Green Roof System (BTGRS) with BauderGREEN XF 301 Sedum Blanket


Mhairi Grant and Martin McCrae, the directors at Paper Igloo architecture practice located in Scotland spent several years building their own Passivhaus home.

A Passivhaus building is designed to decarbonise new and existing buildings. The concept originated from The Passivhaus Institute in Germany and is growing in popularity within contemporary architecture, as the net-zero future draws closer. Referred to as Passive House in English, they use a combination of clean energy generation and energy efficiency to offset any energy use.

This property was the first certified Passivhaus in Stirlingshire, achieving Scottish Technical Standards Section 7: Sustainability Gold Level.

Bauder Building Board

Project: Ostro
Project type: New build
Location: Kippen, Stirling
Waterproofing: Bauder Total Green Roof System
Roof size: 125m²
Specifier: Paper Igloo Limited
Approved contractor: Greenroof UK Ltd

The specification

The design of flat roofs are considered unusual within the location of the project, this meant the client had to make some justification for the roof design choice.

The Architect justified this to the Planning Authority by citing the improved surface water attenuation and biodiversity enhancement that the sedum roof covering would provide. Therefore, the Bauder Total Green Roof system with the XF 301 Sedum Blanket Extensive Green Roof System was specified for this project. The sedum blanket was compatible with the renewable energy technologies also fitted onto the roof.

Products applied

BauderGREEN XF 301 Sedum Blanket
A mature vegetation blanket, sown with a variety of sedums. It is intended for application directly over the waterproofing system without the need for a secondary substrate growing medium, making it the lightest self-contained sedum blanket system available.

Project challenges

With advice from Bauder Site Technician, the installers had to lap the Air and Vapour Control Layer onto the underlay at the perimeter upstand, this meant a slight extension piece was fitted to achieve this.

The BauderPLANT E cap sheet was applied to the flat areas of the roof, and the Bauder K5K cap sheet was installed to the upstand details.


The result

The waterproofing was installed to a very high standard by Bauder-approved contractors GreenRoof UK Ltd. The black pebbles around the roof’s perimeter was the client’s personal choice for the design.

This home has been widely recognised for its excellent design. Winning multiple awards including ‘The Daily Telegraph Homebuilding & Renovation Awards 2021 - Best Green Home and Home of the Future’, ‘Scottish Design Awards 2022 - Chairman’s Award for Architecture and the Winner in Residency category’, and a ‘Royal Incorporation of Architects (RIAS) Award and Circular Economy Award 2022’, as well as being long-listed for the ‘Royal Institute of British Architects (RIBA) House of the year award 2022’.

System installed

Bauder Total Green Roof System with Sedum Blanket

1 BauderGREEN XF 301 Sedum Blanket A sedum vegetation blanket instantly provides at least 90% coverage on an extensive green roof.
2 BauderGREEN SDF A multi-functional drainage and filter layer that lifts the blanket slightly above the waterproofing so that in heavy rainfall areas the blanket, and therefore the roots of the sedums, do not become waterlogged.
3 BauderPLANT E A 1.5mm polyester reinforced Poly Vinyl Chloride membrane (PVC). The membrane has a polyester fleece underside. 
4 BauderPIR FA-TE Thermal insulation with low thermal conductivity.
5 BauderTHERM DS 1 DUO Elastomer bitumen air & vapour control layer, self-adhesive with variable technology for lap sealing.


European Passive House Designer, Director of Paper Igloo, Mhairi Grant:
“From the start of the design process Christopher Langton at Bauder and his team were very helpful. They reviewed our technical design offering guidance to ensure compliance with the warranty, were good communicators, and offered an excellent service throughout. The installation process was also great, with regular inspections and reporting from their operatives to ensure the installation was proceeding as designed. We wouldn’t hesitate to recommend Bauder and their total green roof system with sedum blanket to anyone else who wants to improve the water attenuation and biodiversity of their project.”

Area Technical Manager – Christopher Langton:
“From the initial meetings with Mhairi and Martin about this project, it was a pleasure to help and ensure they achieved everything they needed from their green roof.”