As the subject-line indicates, I've been having a problem with the pies I bake. The top crust balloons up during baking. So when the pie cools, the top crust is not adhered to the filling - it breaks down when you slice the pie.
I do use a 'vent'. I typically cut a 1/2-inch circle in the centre. Too small? Too few? It does seem to allow steam to escape, but... the problem persists.
If anyone has any tips for preventing the undesirable pie balloons, let me know!