I'm no lawn expert, be that known. My soil is also heavy clay. As far as not
mixing sand in the clay, I'd have to disagree. I have used top soil in 75%
of my yard. 25% was clay that I just picked and broke up and mixed with
sand. Get a course bank run sand and mix it in. I feel it does help the
texture. The worst part of clay is it compacts and lets no air into the
roots of the grass. Clay holds moisture more so than any soil so water or
should I say lack of is not a problem for the grass. For the last 5 years,
every spring and fall I spread gypsum pellets. They work into the
established lawn and over time help improve the aeration of the clay. As
far as the french drain? My opinion is bite the bullet. Dig a shallow trench
around the foundation, sloping it so the water runs off. You can put drain
tile in it covered with gravel or just fill with gravel and cover with vapor
barrier. A french drain will not disperse the water effectively in a clay
soil. Just my opinion for what it's worth.
"peter" wrote in message
news:K0h9e.21198$H_5.14634@trnddc01...
I want to redo the lawn in the backyard because it had too much weed, moss,
and the ground does not slope away from the foundation enough (my crawspace
gets wet).

The plan is to till the soil, add compost, add a french drain, regrade the
slope and then reseed the lawn.

After killing off the existing lawn, I found that under the surface it is
crisscrossed with tree roots up to 2-inch in diameter. They appear to come
from a birch tree in the corner. I yanked out some of those roots and have
some more to go. Other than cutting down the tree, is there a way to
prevent the roots from invading the lawn in the future?

Also, the soil seems very clay-like. In fact, when it rains some puddles
would form and drain away very slowly. Should I do something about this,
like add sand?

Some books suggest the french drain be put near the foundation wall. I
fear that losening the soil near the foundation would weaken the support
of the foundation, so I'm inclined to put the french drain on the
perimeter of the lawn, i.e. the lowest point after it is regraded. Would
this work?

-peter