Incorrect drainage falls on a balcony are a silent cause of ongoing damage. When a balcony surface doesn't drain freely to its outlet, water ponds and dwells on the membrane and tile joints. Over time, this accelerates membrane degradation, forces water through even minor joint defects, and causes hydrostatic pressure to build up in the screed layer. It's also a slipping hazard and a maintenance burden for building managers.

Correct falls are not a cosmetic detail — they are a structural and waterproofing requirement. AS 4654.2 requires a minimum fall of 1:80 on trafficable waterproofed surfaces, with steeper falls specified at drain proximity to prevent ponding. Atomic Projects corrects screed falls as part of complete balcony remediation programs or as a standalone scope where drainage is the primary issue.

How We Correct Balcony Screed & Falls

• Falls Survey: Before any works commence, we survey existing falls across each balcony using a digital level or laser to map ponding zones, identify the lowest points, and confirm drain outlet positions relative to the surface profile.
• Tile & Screed Strip: Existing tiles and screed are fully removed to expose the waterproofing membrane or concrete substrate. The condition of the membrane is assessed at this stage — if it has failed or is at end of life, membrane replacement is incorporated rather than re-screeding over a compromised layer.
• Substrate Preparation: The exposed concrete slab or existing membrane is cleaned and primed in accordance with the screed manufacturer's requirements to achieve full adhesion of the new screed layer.
• New Screed Application: Screed is applied to engineered depth and profile to achieve a continuous fall across the whole balcony surface toward the drain outlet, with no flat spots or reverse falls. Fibre-reinforced screed is used where movement risk is elevated to reduce cracking.
• Integration with Drainage & Waterproofing: New screed is finished to correctly seat drain puddle flanges and perimeter upstands before membrane application or tile reinstatement. Where drainage upgrades are required, these are completed within the same scope before screeding.
• Tile Reinstatement: After screed cure and membrane application, tile reinstatement completes the surface, with movement joints installed at perimeters and bays to manage thermal and structural movement without cracking.

Frequently Asked Questions

How much fall does a balcony need to drain properly?

AS 4654.2 specifies a minimum fall of 1:80 (12.5mm per metre) for trafficable waterproofed surfaces. In practice, a fall of 1:60 is preferred to provide drainage margin. Falls should increase near the outlet to prevent the last metre of water path from ponding. Flat or reverse falls are a defect that cannot be corrected without stripping and re-screeding.

Can the falls be corrected without replacing the waterproofing membrane?

If the existing membrane is still serviceable, it may be possible to apply a new screed layer directly over the existing membrane using a compatible bonding system. However, this depends on the membrane's adhesion, condition, and age. In most cases where falls are being corrected, the membrane is also replaced as the cost of stripping makes it economical to do both at once.

What causes incorrect falls in the first place?

The most common causes are inadequate original construction, where screeds were laid flat or the drain outlet was positioned too high relative to the finished surface; screed settlement or shrinkage over time; and renovation work where tiles were relaid over existing screed without correcting the profile. In older buildings, falls were often not specified at all during original construction.

How long does screed need to cure before tiles can be laid?

Standard sand/cement screeds require a minimum of 28 days to reach design strength before tiling, though the actual program depends on ambient conditions and screed depth. Rapid-set screed systems can reduce this to 3–7 days where program is critical. Tiling over green or damp screed is one of the most common causes of tile debonding defects in residential buildings.

Is screed and fall correction a capital works item or a maintenance item?

For strata buildings, screed and fall correction is typically a capital works item funded through the sinking fund, particularly where it is part of a broader balcony waterproofing program. It is a defect rectification if the original falls did not comply with the applicable standard at the time of construction.

Incorrect falls are one of the most easily preventable causes of ongoing balcony leakage — and one of the most frequently overlooked. When combined with correct waterproofing and drainage, a properly graded screed can extend the life of the balcony system by a decade or more. Atomic Projects is a Class 2 Registered Builder with over 10 years of experience in balcony remediation across Sydney. Contact us to arrange a falls survey and scope assessment for your building.