SQL 2012/14 detection methods

Hi,

I have an issue deploying SQL through SCCM.  My detection method is to check the registry for version number.

Current I check : SOFTWARE\Microsoft\Microsoft SQL Server\110\SQLServer2012\CurrentVersion

Version

11.0.2100.60

I have a separate package for SP3 and I check for version 11.3.6020.0

The problem I have is when SP3 installs it thinks the original package is not present.  I package different service packs separately as the user choose what service pack they need to replicate the environment they are building.

I have the same problem with SQL14

Whats a better method of detection for SQL?