"JK" wrote in message ...
Is it possible to lay a lawn on a roof terrace? How would one do it? I
imagine drainage would be an issue, but maybe there's a way round it.

No reason in theory why you can't do it.

All you need is a very large very shallow plant pot :-)

What you are likely to need:

(1) Report from a structural engineer stating that the terrace can support
the proposed load.

(2) A waterproof base (not just one that is O.K. when water falls on it and
runs off, but one that can cope with continuous wetness).

(3) Sides to contain the soil, with provision for drainage - small holes
around the base. I imagine you could line the whole thing with plastic or
butyl as long as you make holes in it for drainage.

(4) A reasonable depth of soil laid on gravel or similar to provide drainage
at the base. I have no idea how deep this should be but I would imagine at
least 6"-9" of soil to provide a resevoir for nutrients and water.

(5) Provision for regular watering - again just as you would need for other
container grown plants.

(6) A plan for cutting the lawn and disposing of the clippings - I guess you
would need a tool shed (or room) for the lawn mower etc.

Plenty of places have lawns on the roof. One notable example is the Willis
Faber (now Willis Caroon I think) big glass building in Ipswich. This has
won awards and featured on several documentaries.

The main issue you are likely to face is the structural strength needed to
support the soil and turf.

Another issue may be the depth of soil needed to prevent the lawn from
drying out and dieing - this will raise the level of your terrace and may
cause problems with access by preventing doors opening.

You should also be careful of raising the floor level to the point where the
terrace railings are below the height specified in building regulations -
assuming the lawn come to or near the edge of the terrace. Don't want people
falling over the edge and spilling their drinks :-)

HTH
Dave R