dubliner10 wrote:

Can I start by apologising if this is the 100,000 time the following
question has been asked but I am struggling to get a decent answer
(from my in laws!)

We have a v.old lawn (60 years), and it is showing its age. Added to
that the soil is very heavy clay, and the drainage is a nightmare.

We plan to dig a soakaway, and lay the special drainage 'pipes' to
drain the worst areas. Once we have done this we plan to top the
ground with topsoil and horicultural grit to help the drainage.

My question is - do I have to completely 'lift' the old lawn or can I
:

a) leave it as is and lay topsoil + grit over it

b) rotovate it and lay topsoil + grit over it.

You can do either.

Your existing grass will grow through unless you kill it all first. If
you want more of the same type of grass, let it live.

I would take the opportunity to mix the new soil in with the old by
rotovating.

--
Steve Bell
New Life Home Improvement
Arlington, TX, USA