Posted: 02/01/2017 at 17:21
First thing will be to level it, otherwise mowing will be a bit of a nightmare. Dig the area over, remove any large stones and any building debris (which you may well find on a new build, it's a very common issue.) Once roughly level, shuffle over the whole area wearing boots or wellies to re-compress the soil and then rake it level again. I wouldn't do any of this until spring as wet clay will compact when walked upon and get worse, so keep an eye on the area over winter and note if any parts of it become waterlogged. If they do, you'll need to dig deeper and add something to improve drainage, such as grit and compost.