I have a function u[y] and I want to find the limit of integration that integration is equal zero.

Λ = -30;
u[η_] := (2*η - 2*η^3 + η^4) + Λ/6*(η - 3*η^2 + 3*η^3 - η^4);
θ = Integrate[u[η]*(1 - u[η]), {, 0, 1}] // N;
δ = 1/θ;
u[y_] := Piecewise[{{1,y > δ}}, (2*y/δ - 2*(y/δ)^3 + (y/δ)^4) + Λ/6*
((y/δ) - 3*(y/δ)^2 + 3*(y/δ)^3 - (y/δ)^4)];

FindRoot[Integrate[u[y], {y, 0, yd}] , {yd, 5}]

I have the following error: "Unable to prove that integration limits {0,yd} are real. Adding assumptions may help."