"To build a base" means to establish a strong foundation or starting point for something. It involves creating a solid framework or support system that can be built upon or expanded upon in the future. Full definition
It addresses an industry need for realistic standards for energy and environmental performance of existing buildings based on accurate, independently verified information. (remonline.com)
As a beginner, you should focus on building a base of strength and mastering technique on a few basic compound exercises — dramatic muscle gains will follow. (kingofthegym.com)
These cards are very important first step in building a base for a good credit score, so it is important for the students to make payments regularly. (echeck.org)