What is the proper way to cut joints in floor toppings one-fifth of the thickness as in regular slabs, or all the way through the topping to the joint in the base slab?
The joint should be located accurately over the joint in the base slab and sawed or formed to one-half the depth of the topping. This is proportionately deeper than joints in slabs and will ensure cracking below the joint. It will also provide support for the joint sealant.