We have just had block paving laid on our drive. the job looks good, but I looked at your website for advice on maintenance and found the stuff about not using polythene sheets between the sand and the sub-base. Guess what our contractor's done?!!
We can't redo the whole drive, but is there any point in getting some bricks lifted and making holes in the polythene? Our drive does have a decent slope away from the house.
No - get a written statement from your "contractor" in which they guarantee to undertake any necessary repairs or remedial work should any problem develop over the next 5 years.
And ask the gormless sods why they've put down polythene in the first place!