Edition 3 – Drainage & Waterproofing
The Australian Institute of Waterproofing (AIW) of which Wet-seal is a member has written an article that appeared in the State based Master Builder magazines, the article was titled “Waterproofing – Common Causes of Failure”.
This news article informs you of another common cause of waterproofing failure – Drainage.
DRAINAGE & WATERPROOFING
- Common failures are caused by poor drainage of surface moisture adversely affecting the waterproofing.
- A builder would not install a metal or tiled roof without the minimum specified gradient for surface drainage.
- This however is not the case with waterproofing.
- It is still a common occurrence that waterproofing membranes are installed on horizontal surfaces without falls for substrate drainage.
- Single component acrylic membranes were renowned for re-emulsification under saturated conditions in the 1980’s and 1990’s. (Wet-seal does not have acrylic membranes).
- While products have changed, the construction methods have not.
- Nearly every part of a building exposed to surface water or conveying water has specified gradients including stormwater pipes, eave gutters, box gutters, sanitary pipes, culvert drains and kerbs.
- A major problem of saturated mortar screeds built up for surface drainage over waterproofing membranes is salt calcification or efflorescence to tile surfaces.
- Waterproofing ideally should be installed to a gradient that creates correct fall for drainage.
- There is a misconception within the building industry that a PVC drainage pipe embedded in or passing through a concrete floor slab is a rain water outlet (RWO).
- The drainage pipe is not the outlet. Providing a waterproof seal and connection to a PVC pipe often results in failure.
- All drainage outlets should be an RWO cast into the concrete slab and connected to the drainage pipe.
- The RWO will provide the required flange for connecting the waterproofing membrane at the drainage point.
- A major problem in subsurface drainage is sleeved PVC floor grate housings which are pushed into drainage pipes damaging the membrane junction and blocking subsurface drainage.
- Whilst waterproofing is designed to protect the structure and prevent water ingress into the building there is often little consideration given to the drainage to ensure the waterproofing membrane’s performance.
- The failure of waterproofing is often associated with poor or non-existent drainage particularly at the subsurface level.
For any other advice of a technical nature, Wet-seal’s highly experienced technical expert, Robert Rath, will be happy to take your call. Robert can be contacted on 0413 008 303 or via email firstname.lastname@example.org
Alternatively, please speak with your local Franchisee directly. Details of how to contact your local Franchisee can be found at Find A Franchisee