I am getting ready to replaster my pool. It is a 25,000 gallon kidney shaped pool with a 10 foot diving end that I want to make a 6 foot depth prior to the new plaster. I have gotten several contractor bids and been told that what I am proposing is not that uncommon. However, one of the contractors mentioned that he would fill the deep end in with concrete or gunite and I should be aware that where the new gunite joins the existing gunite there will be a risk if cracking (even though they will drill into the existing gunite to tie-in new rebar). This is because the new gunite will taper down to be very thin where it meets up with the existing gunite.
None of the other contractors even mentioned this possibility. Does anyone have thoughts on how likely it is too crack or can someone suggest a method to reduce the risk? One person mentioned you should jack hammer into the existing gunite a couple of inches deep where the new gunite will join the existing gunite and then level it back with the new gunite to avoid a thin area. Any thoughts would be appreciated.