Concrete flat roof on all buildings should be construct based on the principles for managing water known as the 3 Ds – diversion, drainage  and durability. 

1. DIVERSIONS - the art of protecting the joints

First thing to think about is to redirect water that is being forced onto the roof and direct it elsewhere before it infiltrates or absorbs into the substrate. Keeping water away from entry points will greatly reduce the chance of a joint developing a leak. 

Eg: Roof decks, balconies and any exposed areas should be designed with a slope to fall. Gutters to be designed on flat roof. Vertical drainage mats to be installed to below grade walls.

The longer the area is exposed, the higher the risk of water penetration

2. DRAINAGE - allowing unwelcome water to escape

It is important to allow for water which has entered to drain away. Envelope components that might permit water absorption and some infiltration through substrate but provide a means to collect this water and divert it back out to exterior before causing leakage.

3. DURABILITY - waterproofing membrane that last

Choosing the right waterproofing system and waterproofing membrane with good properties such as tensile strength, elongation and crack bridging ability is highly essential to withstand the harsh outdoor environment.

Waterproofing systems that are protected with a protective mortar screed is always recommendable because we always want the acting barrier of the waterproofing system to be the last line of defence from water infiltration.

If waterproofing systems are exposed, it is essentially being put as the first line of defence from harsh conditions such as hot temperature from direct exposure to sunlight, heavy rainfall and UV ray attacking the membrane.

The protective mortar screed can be installed with a slope to fall above the Roof top Waterproofing system which will serve two important functions: a diversion for rain water and extra protection over the waterproofing system.

The Importance of 3 Ds in Construction and Renovation

The importance of using this basic principle when building and renovating your property will will ensure that construction is robust and durable and will manage any water that impacts upon the building or penetrates the exterior cladding. On top of that, you’ll have a healthy and sound structure over time worry free!