today i will represent simple trick to building an RPM without having root access. You can build it in your home directory
In this tutorial we will see how to create the RPM build directories and how to setup your ~/.rpmmacros
The .rpmmacros file is used by rpmbuild to provide defaults. You may find references to the .rpmrc file, but it has been deprecated in favor of this file.
we need also to create build directories. By default, rpm will expect to find and use the following directories:
%{_topdir}/BUILD
%{_topdir}/RPMS
%{_topdir}/RPMS/i386
%{_topdir}/SOURCES
%{_topdir}/SPECS
%{_topdir}/SRPMS
I will not do this manually i will use herrold script 
let start
Building Source RPM as non-root under CentOS
Ref : http://www.owlriver.com/tips/non-root/