@ Wouter
I'll post the measurements later today when I come home. Thxa lot for the effort.

@ Mary
It's not the Sea Spray; looking at these photos my cat is much larger. The cat was home built by the plans of some English designer about 15 years ago. I don't know the name of the original designer, since I've bought it used. I'm form Europe, Slovenia.

@ arbo06
Yes, I have 3 beams.