I am considering extending my pond and wondered if it is possible to link two pieces of butyl liner instead of relining the whole pond..The pond's current dimensions are 8ft by 6ft and around 4ft deep... I've seen butyl linking tape on the internet...Will this be suitable for such a project and is it likely to last?
Join the liner etc, it leaks, give up, buy a new bigger liner. So you have wasted money on another liner and a lot of tape.
You really can join a liner with specialist tape, but you have to make sure both edges /surfaces to be joined are spotless, and you should use a roller and a flat surface to make sure there is a good bond. Usually this is done at the build stage, not a few years later, the other thing to consider is that although butyl lasts for many years, one part of your proposal will be considerably older than the other.
You don't have to use butyl for a liner, there are a whole variety of other non butyl liners out there, some even have a life expectancy longer than butyl, and cost less.
Good quality costs. Bear this in mind before you start.
Sorry if my reply is NOT want you want to hear, but what I have said is true.