We are very grateful that you have taken the time to share your review on Shaw Vista Shoreline. It is very important to prepare the subfloor before installing this flooring. All subfloors must be clean, flat, dry and structurally sound. Subfloor must be at – 3/16" in 10' or 1/8" in 6'. During the installation, you may need to use a pull bar, rubber hammer and a tapping block to assist with locking the sides together, but you are correct, once they are locked, you will know. This product is very durable and we hope that you enjoy your new floors for many years to come. We have a Consumer Concierge team available if you should have any questions or concerns. Please contact this team at askshaw@shawinc.com or (844) 742-7429, Monday through Friday, 8 am until 6 pm est. Thank you again for the review and have an awesome day!~clf