Balcony Slab Waterproof Job

Why so much different waterproof job price in market, a big gap different with different contractors

We do a right step for waterproof job 

• hacking old concrete 
• 3 time lay waterproof 
• Air leaking testing 
• new floor level 
• adhensive cement tiles work 
• 30/60 porcelain matching 30/30 decor tiles