I had a company encapsulate my crawlspace with 20 mil liner. The liner installed has 3 dime size holes as well as a 4-5 inch gash they covered with tape. They now would like to cover the holes with tape as a fix. They also mentioned they are going to foam then since they have to come back. Is the only real fix for them to reinstall a new liner or is there an actual fix to this? What issues can I have in the future?
It is a common practice to patch seams and holes in the vapor barrier with tape. The type of tape you need is often called house wrap tape. You can get it at your local home improvement store.
If you use the correct tape, then you shouldn't have any issues with it.