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Questions on green roofs

  • What deck should be used beneath a green roof?
    When deciding on a deck, thought should always be given to the loading it will have to take.  It is possible to use a concrete deck with a wood float finish, metal or timber (plywood should be an exterior WBP grade).  If you are considering an alternative deck, please give us a ring and we will confirm suitability with you.
    More about weight loadings of a green roof
  • I need a really lightweight green roof, what should I use?
    The lightest weight green roof is the XF301 sedum blanket system which is a pre-cultivated 'turf' comprised of low growing, low maintenance succulent plants (sedums) that is rolled out directly on top of the root resistant or protected waterproofing.  It only has a saturated weight loading of 44Kg/m² making it ideal for new build or retrofitting to a current building.  More about sedum blanket green roofs
  • How do I look after my green roof?
    All green roofs require a minimum of two inspections a year to ensure that the rainwater outlets are maintained.  An intensive green roof will need the regular care associated with the garden planting scheme and landscaping.  An extensive green roof will only need minimal maintenance to ensure that any unwanted species do not become established. More information on maintaining a green roof
  • What is the difference between substrate and soil in a green roof?
    A substrate is a lightweight alternative to soil which reduces weight loadings on the green roof whilst still providing a base for the plants and vegetation to grow in.  It doesn't hold nutrients as efficiently as soil and so annual applications of granular fertiliser are often required to sustain the plants. More information on green roof components  
  • My extensive green roof is to incorporate a vegetation barrier.  What is it and why will it be on my green roof?
    A vegetation barrier is created using washed round pebbles and is primarily incorporated to prevent vegetation encroaching on elements such as rainwater outlets, provide wind uplift resistance at roof perimeters.  More information on functions ►
  • How do I decide between having a green roof or PV on my roof and which gives the best environmental benefit?
    You don't have to choose between the two technologies, you can have both in an integrated solution.  A BioSOLAR system incorporates a water retention board in the mounting system and uses the substrate and vegetation as the ballasting mechanism for the installation method.  A key element of a combined system is that the PV panels are elevated to allow for vegetation growth without blocking light to the modules.  More on BioSOLAR
  • What is the weight loading of an intensive green roof?
    This is dependant on the depth of substrate and the planting scheme, though a typical guide for a roof garden ustilising 200mm of substrate would be 270Kg/m².  This system summary pdf covers the components typical and the associated weight loadings or more information on our website regarding a generic roof garden build up
  • What is a sedum blanket?
    It's a pre-cultivated vegetation mat incorporating a mix of established sedum plants that is supplied in a 'turf' format to be rolled out onto a roof giving instant coverage.  More on sedum roofs ►
  • I need to incorporate a green roof to meet a Biodiversity Action Plan (BDAP), what shoudl I be specify?
    This will depend on what biodiversity species you need to encourage on the roof and the plants stated in the report.  If the requirement is more generic, you can consider a wildflower blanket or seed mix which will satisfy the requirements of BREEAM or planning.  More on biodiversity green roofs  ►