What is the best way to do a waterproofing of an old concrete roof?
There are many numbers of systems. Most affordable options include Acrylic Cementitious Waterproofing Coating, IPS Coba, etc. But it all depends on several factors such as
How old is the slab?
What is the present status?
What is the life span expected?
What is the budget considered?
The best way to waterproof old concrete roof/terrace depends upon the surface conditions and the age of the structure/roof.
The best option which is Polyurethane Coating. The procedure involves surface preparation with wire brushing followed by cleaning and filling the exposed cracks with elastomeric material. Then priming the surface for better adhesion of the PU coating. Then apply the coating using brush/roller/spray in two coats. Ponding tests can be done to ensure zero water leakage. Although this system is little expensive but for achieving long term results and durability this system can installed.