you must paint or coat the ends with wax to slow down or prevent splitting. There are products specifically for this purpose but things like mobile home roof sealers will also work.
As for the 14% M.C., how did he come up with that figure? If he had a moisture meter, he would have volunteered to show you just as a matter of salesmanship.
Tony B Retired woodworker, among other things.
"Strive for excellence and settle for completion" Tony B