Is it safe to make 11cm holes in balcony beams

It's hard to say. The balcony beam is not large, and the force of the beam after punching has to be somewhat affected.

Strictly speaking, the beam body is not allowed to open holes, if it is really necessary, the size of the holes should also be controlled, and the height of the beam is generally 40-50 cm high. It is recommended that the maximum opening of 10 cm is better, and try to stagger the main reinforcement (the upper and lower parts of the beam are the main reinforcement) that is, the middle hole of the beam.

The design load of the balcony is regulated, and the beam of the balcony is an important component that supports the balcony, and for the safety meter, the component that bears the load is not perforated. It is not uncommon for balconies to collapse in use, causing casualties. If you really want to drill the hole, you should ask the original design unit or a qualified design unit to come to investigate and conclude whether you can punch the hole.

If the design unit can not punch holes in the final conclusion, you can ask them to make a strengthening plan, choose a suitable place, draw drawings and instructions, stamp the official seal, and strengthen the construction of the balcony and beams according to the drawings to achieve your purpose.