Tiled balconies, decks and podiums areas are also notorious for leaking and are usually much more difficult to fix so every effort should be made to get it right first time.
New Balconies, Decks and Podiums Construction
Concrete shrinks and cracks, bricks grow and crack, fibre cement (FC) and plywood sheets shrink at the joints. Hence it is obvious that the membrane used must have elastic properties. First option is to use fully bonded SBS bitumen sheet membrane wherever possible, second option is to use solvent based Polyurethane and related Polyurea and possibly SBR latex
Since FC and Plywood is nearly always butted, a 2mm movement in a 1mm joint is 200%. For this reason, specify Wrimco SBS for these substrates. Because liquids are difficult to apply uniformly to the desired average thickness over large areas, best to limit their use to small balconies and to stick with Wrimco SBS sheet membrane especially for decks and podiums and where over habitable rooms.
If the membrane is accidentally cut while a mortar bed is being spread, this can lead to disaster. If the membrane has been water tested OK, then warranties go out the window. Water testing the tile bed is rarely carried out by the tiler.
The answer is for the waterproofer to spot torch or glue XPS protection board over his work. Besides protecting the membrane, this 6.4mm extruded polystyrene (XPS) fan fold board will virtually eliminate heat transfer in the hot summer months and provide impact sound resistance to CSIRO requirements, of particular importance for balconies over habitable rooms.
How the membrane terminates is of critical importance. Since screeds and mortar beds tend to shrink, it is best to separate them from the membrane with a bond breaker such as closed cell polyethylene foam (Abelflex). If pre-slit to apply a urethane sealant, then care must be taken to seal the SBS from the solvent in the urethane sealant with WBE primer. Better still is to stop the SBS at or just below tile height and applying an acrylic to say 50 above finished tile height so there is no tendency for shrinkage of the tile bed to pull the SBS membrane off the wall.
The mortar bed itself should be waterproofed as a second line of defence and to prevent efflorescence and discolouration that may occur with porous tiles like marble and travertine from the damp alkaline mortar bed.
Prime with WBE and apply two coats of acrylic. Make sure the bed is sealed around the edges. Steps and balcony edges without turn-ups are particularly prone to exhibit efflorescence which is the leaching of lime by water to form white crystalline calcium carbonate (limestone).
Finally, seal the tiles with a water repellent type sealer such as Wrimco supplied S900 Siloxane but if highly glazed, just seal the grout between the tiles.
Repair leaking balcony, deck or podium
Obviously the first thing to do is to try and identify the source of the leak and its location by removing the Gyprock to reveal the crack in the concrete. This will however not help you if the membrane used was a loose laid membrane, you would have to check for any recent activity such as installing AC, satellite dish or solar panel. If you can find nothing; then try sealing the tiles. If this does not work then everything has to be removed and you start again with the fully bonded Wrimco SBS sheet membrane system with XPS protection board / insulation board.
A frequent cause of water penetration is due to water bypassing the membrane system, especially where there are structures above the balcony in question. Check that flashings are functioning as intended, walls are properly sealed, windows and doors drain correctly, etc.
When appearance is not of importance, then simply torch apply Wrimco SBS Granules or an appropriate urethane system over the tiles to solve the problem.
