In regards to extra material overhanging the pool wall for Overlap Pool Liners, this extra pool liner material may vary. But here is some general information that may help you when installing new above ground pool liners, in ground swimming pool liners, and replacement pool liners.
Depending on whether your pool wall height is a 48”, 52”, or 54”, this will determine the amount of excess material. In general, there should be an excess of 3”-6” of pool liner over the pool wall. It is best to almost always keep approximately 2” of the 3”-6” excess material over the pool wall for cold weather shrinkage purposes. You don't want your pool liner pulling inward into your pool water during the winter season. The remaining 4” can be folded and tucked under the coping and top rails of your swimming pool.