by Michael Smith (Veshengro)
A green roof, or living roof, can aid to regulate the temperature of a house or building by keeping it cooler in the summer and warmer in the winter.
In essence one could even graze some goats on them as goats can indeed climb ladders being quite agile. In fact in many mountain areas this used to be a rather common sight, as well as in some Scandinavian countries.
Generally only grass and/or wild plants that do not require deep soil are used, or found, on living roofs, and it is better to plan a building from the beginning to accommodate a green roof, as retro-fitting is an expensive idea.
If you have the right kinds of roof that is not too steep you could retrofit a green roof, sort of, in that you could have plant boxes on your roof in which you could grow either wild flowers or even herbs, if you can access the boxes for harvesting.
It must be considered though that soil, especially wet soil, is heavy and many a roof that was not built for a green roof might not withstand too much of that kind of weight. The flat-roofed garage, for instance, might be a candidate for the use of planters for wild flowers, bedding flowers, or herbs, especially if the roof is tar-paper, aka roofing felt.
As said previously, the real green or living roof is only something for the house that has been designed and built with it in mind. Retro-fitting is a little too difficult and costly.
In the future we could be seeing more green roofs as standard incorporated in the designs of homes and especially into the self-build ones. The earthships are a real example of this but so are the houses with grass on the roofs in other countries that are already a design that is centuries old.