For those who are very much interested in architecture the NAI - Netherlands Architecture Institute has special tours and can be visited. Go to the official site http://www.nai.nl/ or visit them.
The fees include the entrance to Sonneveld house:
Adults 8 euros
Children up to 4 years of age free
Children between 4 and 12 1 euro
Youth between 12 and 18 5 euros
The post image is from one of Rotterdam buildings.