Hi,

Can anyone help? I have recently seen a shed roof turned into a garden. How is this best done so as not to damage the roof of the shed?

Cheers,

Devil

Our Gardening Expert replies::

Hi Devil,

You've hit the nail on the head here - it's crucial that the shed walls and roof are strong enough to take the weight of whatever you are putting on top. Often roofs are specially reinforced even to the extent of having a substantial exterior quality waterproofed plywood layer. On top of the plywood goes robust waterproof sheeting - sometimes metal sheeting is used. It's also important to deal with the edges of the roof properly so that moisture cannot enter that way.

The compost that is used on the roof is determined by what type of plants you want to grow. For example, Sempervivums and quite a few small-leaved Sedums will actually grow quite happily just on top of roofing felt. But if you want a proper 'living roof', these usually consist of a mixture of species containing grass - often Festuca and a few spreading Sedums, such as Sedum oreganum, and Sedum spathulifolium. Along the edges you could put Saxifraga oppositifolia to trail downwards and maybe a few Sisyrinchium douglassii for flower power! Ferns will often grow well in these situations - Blechnum or Dryopteris types should be successful. With such a mixture you may need a drainage layer before adding the compost.

Don't get too carried away though - if your shed is a prefabricated one, bought in a kit that you have erected yourself, it is very unlikely that it will be strong enough to take the substantial weight represented by the above. You would be well advised to substantially strengthen the walls and to consider replacing the roof if necessary.

This is quite a good project to undertake and the results, if successful, can be spectacular but you need to plan carefully before proceeding.

Good luck!

Sibe.