Balconies & Podiums

Failed Screeds

Balcony and podium screeds provide the drainage falls and surface substrate for tile and waterproofing systems. Screed failure — through cracking, delamination or inadequate falls — undermines the performance of all finishes above it. A delaminated screed creates a void that collects water and prevents the membrane from drying, accelerating failure. Cracked screeds transmit cracks to the membrane and tile system above. Screeds with insufficient falls trap water on the balcony, increasing hydrostatic pressure on the membrane. Screed failures are frequently discovered during tile removal works and must be fully addressed before any waterproofing system is reinstated.

Common Signs

Hollow sound when tiles are tapped over large areas — indicating screed delamination
Cracking of tiles following the pattern of screed cracks below
Ponding water on balcony surfaces — indicating inadequate screed falls
Screed visible at broken tile edges in a friable or low-strength condition
Delaminated screed sections lifting with tiles during removal
Drainage outlets sitting above the screed surface level
Previous screed repair patches that have themselves cracked or delaminated

Common Causes

Screed applied too thin — less than 25 mm minimum for bonded screeds
Screed applied to a contaminated or un-primed substrate reducing bond
Insufficient drainage falls formed in the screed — minimum 1:100 to outlets
High water-cement ratio in the screed mix causing excessive shrinkage cracking
Screed not protected from rapid drying during curing in hot or windy conditions
Drainage outlet frames not set at the correct level before screed is applied
Heavy loads applied to the screed before it reaches sufficient strength

Risk of Neglect

Water entrapment between the screed and membrane accelerating waterproofing failure
Crack transmission from screed to the membrane and tile system above
Ponding from inadequate falls increasing membrane hydrostatic loading
Significant tile and waterproofing system cost if failed screed is not identified before relaying
Screed replacement required — cannot be repaired in place where delaminated or cracked
Ongoing staining and structural deterioration if water is trapped in the screed layer
Total system failure if screeds are reinstated without addressing the underlying issues

Inspection Requirements

Conduct a full hammer tap survey of the balcony surface to identify delaminated screed zones.
Lift a sample tile and assess the screed condition — test strength by scratching with a key or nail.
Check screed falls at drain locations using a digital level — falls should be minimum 1:100.
Measure screed thickness at exposed edges or break-out locations — minimum 25 mm required for bonded screeds.
Assess the substrate under the screed where delamination is confirmed — check for contamination and moisture.
Inspect all drain outlets to confirm they are set flush with or below the screed surface.
Engage a waterproofing consultant to assess whether the membrane below the screed has been compromised.
Document the extent of failed screed with photographs and measurements for the removal and replacement scope.

Start Inspection Checklist

Create a project inspection record, add defect locations, upload photos, and save notes for scope writing.

Typical Repair Methodology

01.Remove all delaminated and cracked screed identified in the survey — do not attempt to patch screed in place.
02.Remove all adhesive and remaining screed material to expose the structural slab or waterproofing membrane.
03.Clean the structural substrate of all dust, contamination and adhesive before applying a new screed.
04.Prime the structural substrate with a compatible screed bonding agent.
05.Set all drain outlet frames to the correct finished level before placing screed.
06.Apply a polymer-modified sand and cement screed at minimum 25 mm thickness, formed to achieve a minimum 1:100 fall to all drainage outlets.
07.Cure the screed for a minimum of 28 days before applying the waterproofing membrane system.
08.Apply the waterproofing membrane over the cured screed in accordance with AS 3740.
09.Conduct a flood test before relaying tiles.
10.Lay tiles using a polymer-modified adhesive with minimum 95% coverage and appropriate movement joints.

Related Repair Systems

Screed removal and replacement systems
Polymer-modified screed systems
Screed fall reformation systems
Waterproofing membrane systems over screed
Drainage outlet installation and adjustment systems

Open Repair Systems →