Green Roof FAQs

Simply put, a green roof is a vegetation layer covering a roof structure. Sometimes a green roof is referred to as a grass roof, living roof, roof garden or sedum roof

Intensive roof greening usually requires irrigation and maintenance, as the roofs have plants of reasonable size for a traditional roof garden. Extensive green roofs are very low maintenance and largely self sustaining. We firmly believe that due to its unique properties Riefa® Board is the best green roofing solution on the market.

Riefa green roofs do not require any irrigation in the UK, the boards and sedum turf are capable of surviving and thriving in extreme conditions of drought for at least 6 weeks. However, at the time of installation considerable watering is required.

* High water absorption and releasing capacity up to 11 l/m2
* Perculation rate of 1 litre per hour
* Temperature regulating properties, resistance against ultraviolet radiation
* Non-residual, because boards consist of regrowing raw materials and mineral additives
* Low density and thus low weight of 250-350 kg/m3
* Excellent structural stability
* Neutral pH values between 6.5 and 7.5

There are many benefits of having green roofing for your home or place of work, including a number of significant structural, environmental and social benefits. Riefa® green roof systems are an ecologically and economically useful alternative for conventionally covered roofs. 

Benefits include:

* Due to the light weight of Riefa® Board you are able to retrofit it to existing conventional roofs – both pitched and flat
* Cost – a Riefa® Board greening system is a fraction of the cost of any conventional green roofing systems on the market
* Speed – The light weight construction makes fitting quick and easy
* Low maintenance – Like conventional roofs, an annual inspection is all that is required
* Energy conservation – save on heating costs thereby saving on your carbon output
* Sound insulation – Riefa® Board is ideal for properties in high noise areas (e.g, near airports) or where noise abatement is required (e.g, respite homes, recording studios)
* Improved biodiversity
* Extend the life of the covered roof – by up to three times over a roof that is exposed to the elements and UV radiation
* Improved air quality – Riefa® Board with a vegetation layer will absorb not just CO2, but also dust particles
* Storm water management – planted Riefa® Board will not just significantly reduce water off-flow, it will also filter the water that passes through it. Reducing lead, copper, cadmium, zinc, nitrogen and other impurities that flow off into rain sewers and the surrounding rivers

Riefa® Board is an innovation in roof greening systems. The lightweight boards are based on natural and renewable raw materials according to a patented process. Riefa® Board guarantees a stable, sustainable, secure medium for the development of hundreds of different types of vegetation. Riefa® Board is also the first and only system available that is completely suitable for retro-fitting to existing pitched and flat roofs. This is due to Riefa® Board’s ultra light weight.

The applications for the Riefa® Board system really are countless. The only limitation is your imagination. Due to its unmatched lightness, Riefa® Board is fully retro-fittable to existing pitched or flat roof applications. Once moistened Riefa® Board becomes extremely flexible without tearing. This means it can be molded around and/or pressed into extreme contours (e.g, gullies, tight curves and apexes). But Riefa® Board is so much more than a green roofing solution, almost any surface can be covered with Riefa® Board and sedum. From a garden shed or bus shelter right up to an airplane hanger. It’s even been used as part of a modern art installation! And due to the excellent erosion reduction properties of Riefa® Board it is also ideal for covering embankments and cuttings, giving them an instant, beautiful covering of living colour

Place the Riefa board on top of the waterproof membrane and then water intermittently until soft. Once the board is soft, you can place the sedum (or other vegetation covering) on top. Then spray the sedum with more water. During particularly wet weather you may want to use less water and the opposite may apply during a dry spell. Further details on installation can be found on our installation guide sheet which you can request via out contact form

NB. If working on a pitched roof, you may require more water due to greater run off depending on the degree of pitch. The absorption rate on pitched roofs under normal conditions tends to be longer than on a flat roof.

There is no minimum pitch specification for our green roofing system. If you have a specific question regarding the pitch of your roof then please do get in touch. We are always more than happy to answer your questions.

The Riefa® green roof system is very easy to install. The ultra light weight nature of the board and the ‘ready to roll’ pre-grown sedum vegetation layer means no specialist tools are necessary. This makes it an ideal product for everyone, from professional roofing contractors and builders right down to a competent D.I.Y enthusiast

All of the roofs referred to by the GRO, in fact those manufactured and fitted by the main sponsors of the GRO, are plastic or oil based , whether it be in the membrane or the plastic trays in which the water and granules sit , all these are flammable.

It makes sense when you are using combustible materials to take some measures to limit the initial spread of flame, the GRO/FFL also recommend that fire breaks are installed every 50m2, again to limit the spread of flame.

RIEFA is of course 100% organic , but more importantly, as it is always wet, whilst not fire proof, it is non-combustible, and therefore non-compliant with the GRO/FFL guidelines in that regard.

We feel that the guidelines should be reviewed. However, as Riefa is not part of the Alumasc/Bauder sponsorship team, we don’t think that will happen soon!