A Roof with an Alpine View

Now this one hell of a view. A small scale green roof with  an Alpine view in the Canton of Valais, Switzerland. Built on top of a garage in Vex, this is the home of the parents of  a good friend of ours, Nathalie Baumann.. Nathalie has been researching and working on green roofs for over 10 years. Her main focus of research initially was breeding birds on green roofs. Now she is also working on green roofs, solar panels, biodiversity and pollinators – a project aptly named Biosolarroofs.com.


 

Slate green roof
Roof with an alpine view using local substrate

What is interesting about this roof is that it is now three years old. The vegetation has established well, but for many, the fact that it is not totally green may be a challenge. However Nathalie says ‘ my colleagues and I are very happy with the growth and how the plants planted are spreading…the roof has no neophytes or invasive plants.’

Roof with an Alpine View – use of local natural substrate

Substrate for a roof with an Alpine View
Slate waste from road and tunnels makes a good green roof substrate

Slate is a local material in the Canton of Valais.Therefore it is the perfect material for a roof with alpine view. Valais is also one of the drier areas of Switzerland. Therefore moisture is a real factor, when making a green roof. And this is where slate comes in. Nathalie points out:

  • Slate has natural properties that make the aggregate retain moisture
  • The course material (0mm- 60mm) the different shapes and sizes help to keep humidity with in the substrate
  • The course material and varying shapes also helps to collect dew in the morning, helping the plants during the especially dry periods experienced in the summer in Valais
  • Tests under lab conditions have shown that slate can retain up to 60-70% of the moisture that falls as rain and the slate collects itself from the atmosphere
  • And slate is local and natural – and it really is thrown by the wayside as tunnels and roads are constructed in Valais

So using a locally sourced growing medium that is sadly wasted adds another ‘sustainability’ plus to this roof.

Roof with an Alpine View – Lessons learned

Whilst the vegetation cover is well below what many in the green roof world would expect/desire, Nathalie and her colleagues think that they would blend the substrate slightly differently for  future projects. ‘Better blending would ensure that there was more air in the growing material.’ Furthermore they would double the planting. The roof was not seeded. They only used native wildflower plugs. Doubling the planting regime would give more cover and provide more spread from self-seeding over a three-year period.

The roof is planted with a good selection of native southern, central European wildflowers:

 

Common Name Latin name
Harebell Campanula rotundifolia
Yellow Harebell Campanula thyrsoides
Fairies Thimble Campanula cochlearifolia
Mountain Onion Allium lusitanicum
round-headed leek/Drumsticks Allium sphaerocephalon
Mouse-ear hawkweed Hieracium pilosella
broad-leaved thyme Thymus pulegioides
Spring Cinquefoil Potentilla neumanniana
St. Bernard’s Lily Anthericum liliago
Stiff hedgenettle Stachys recta
Wild strawberry Fragaria vesca
Common Speedwell Veronica officinalis
Barren Strawberry Potentilla sterilis
Hyssop Hyssopus officinalis
Winter Savory Satureja montana
Goldilocks Aster Aster linosyris

 

 

There are several here that are not native to the UK but are real.

Slate green roof
Roof with an Alpine View

Roof with an Alpine View – the final word

The final word should go to Nathalie’s father, who built the roof with Nathalie’s colleagues…

As my daughter is involved in green roof planning, designing and installing. iIt was good for me to have ago. I’m not experienced in this field. Therefore I was a bit suspicious as well as to whether it would work.

In fact it was for me very interesting to go into this process to understand how such a surface can become green. It was good to understand how it provides  good ecosystem services.

So now three years after the installation, I can see the growth and the changes in the plants.  I can also now understand that it is a complex system that does work. And of course a roof with an alpine view is worth it!’

 

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