need landscaping advice

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
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I think you're stuck with the roots, I had a tree like that once and they were just all over the place. However on that issue and on the issue of clay soil, the real question is whether you can grow grass or not. Clay soil is a drag to deal with, grass eventually did take hold in my case but it took a few years to look like a lawn at all. I have seen on tv where they'll put organic matter back into the soil as you are probably contemplating. Not sure about sand; sand does not absorb water and if you have clay down 3 feet, it might turn out to be the same situation. Sand or granular matter in a houseplant's pot works because there's holes at the bottom and the water can run out, but does the rain water have any place to go ?
I think the french drain really does go by the foundation. That is SO much work though it may be worth paying someone to do it, or pay them for their advice. For example, does a french drain function the way you want it to in clay soil ? I have no idea. I cannot imagine shoveling a trench in clay soil but if your crawl is wet it's gotta be done.
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Shallow tree roots may be a sign of too frequent watering or standing water, or very shallow water table. Trees shoot out surface roots when they are drowning, or lack oxygen due to impervious clay soils. Before trying anything drastic, I would water the lawn infrequently, but deeply. That tends to grow grass better than weeds. It also causes grass and tree roots to grow deeper, making them more resistant to drought. If you are already in the process of regrading, the drain and resloping will help, but not without changing watering frequency as well. Sand does not help drainage in clay soils, it turns it into concrete like stuff. Organics break down clay quite nicely. You should consult a lawn and garden book for your area, and pay special attention to watering and soil conditioning practices. Your local ag extension office and nurseries will also provide brochures on how to improve clay soils.
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SO
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If you install the french drain by the foundation, don't forget to have termite treatment reapplied. Disturbing the soil near the foundation breaks the termite barrier and it will need to be reestablished.
Bob S.
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Throw down sheets of plywood over the entire yard.
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My pecan trees have virtually no shallow roots. My pine and willow trees have shallow roots that are pervasive. Deep and infrequent watering helps.
The sand will help and now is the time to apply it liberally.
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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.

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peter wrote:

Ix-nay on the sand. Use Gypsum. Use a LOT of Gypsum.
Gypsum turns clay into a cross between peat, compost, and bottom-land.
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