In message , Andrew Mawson
writes
I may have to cover perhaps a 1/3 acre of builders rubble that a
previous owner has used to infill a small valley (amazingly with
planning permission it being greenbelt) with soil to return it to a
semblance of normality. It will probably only be grassed over and
possibly used as paddock

People are telling me that bricks will 'float' up from below through
the soil - has anyone any experience of this phenomenon, and what is a
reasonable depth of top soil to aim for?

The proper solution would be to lay a membrane before spreading the
soil. Allows the water through but retains the soil.

I don't have a URL but they are commonly used for horse *menage* areas.
We tend to find them used the other way i.e. to prevent hard surfacing
disappearing into the soil.

I guess 1/3 acre worth would be costly:-(

Google on terram.

Grass will grow on a concrete yard in a few mm of soil but will be very
drought prone. Assuming you are going to seed the end result, why not
speak to a seed merchant and explain your problem. He may be able to
recommend drought resistant varieties.

regards

--
Tim Lamb