how much disk space it need to build from source?

[moonmoonbird]

i followed the process:
# pkg install git
# cd /usr
# git clone https://github.com/opnsense/tools
# cd tools
# make update
# make dvd

my disk is 80GB SSD, after 5hours more or less, error occurred : no more space, /usr/ports and /usr/src took much space. each took 40GB around. so why it too so much space and how much we need.