A leaking terrace is not just a problem for the owner of the upper apartment — water that penetrates the slab slowly corrodes the reinforcement, damages the tenant below, and a repair postponed until "next season" ends up costing twice as much. This article describes how to determine where the leak actually is, what the repair options are and how much it costs.
Why Terraces Leak — Most Common Causes
- Old or damaged waterproofing — bitumen membrane or coating on an older terrace cracks from UV rays, frost and thermal cycling. The lifespan of a standard bitumen membrane is 10–15 years without maintenance.
- Damaged or cracked tile grout — grout is not just aesthetic; it prevents water from penetrating the layers below. A cracked grout line is an entry point for moisture.
- Poorly installed drains and outlets — if the drain lacks a proper waterproofing collar, water bypasses the insulation layer directly alongside the pipe.
- Capillary moisture through the parapet wall — a terrace can "leak" at the junction of wall and floor, rather than through the slab itself.
- Expansion cracks in the concrete slab — concrete expands and contracts; without proper expansion joints, cracks are inevitable.
How to Diagnose the Problem
Before calling a tradesperson, you can narrow down the cause:
- Does it drip immediately after rain? Water is not passing through a thicker layer — look for a crack in the floor or drain.
- Does it drip 12–24 hours after rain? Water is passing through multiple layers — the waterproofing membrane below the floor is damaged.
- Only the edge or corner is wet? The junction of the terrace and wall (parapet) is likely leaking, not the centre of the slab.
- Only wet around the drain? The drain lacks a properly installed waterproofing collar.
Hose test: If you're unsure where the water is coming from, you can spray a hose (not under pressure) on a specific zone and observe. Start from the drain, then move toward the walls, then toward the centre. Useful before calling a tradesperson — it shortens diagnosis time and reduces cost.
Types of Repair and Costs — 2026
Grout Repair and Localised Damage
If only the grout is cracked or there is localised tile damage:
- Belgrade: re-grouting terrace (10–20 m²) 8,000–15,000 RSD labour + materials; replacing individual tiles 1,500–3,000 RSD per tile
- Pančevo: 6,000–12,000 RSD for re-grouting; tiles similar
- Valjevo: 5,000–10,000 RSD for re-grouting
Hydrophobic Coating (Temporary Solution)
Applying liquid waterproofing (acrylic or polyurethane) directly onto tiles without demolition:
- Belgrade: 1,200–2,000 RSD/m² (labour + materials); 15 m² terrace — 18,000–30,000 RSD
- Pančevo / Valjevo: 1,000–1,700 RSD/m²
- Durability: 5–8 years with annual inspection. Not a substitute for a full waterproofing renewal.
Complete Waterproofing Renewal (Permanent Solution)
Floor demolition, slab repair, new membrane, new floor:
- Belgrade: 6,000–12,000 RSD/m² total (all-in — demolition, waterproofing, new floor)
- Pančevo: 5,000–9,000 RSD/m²
- Valjevo: 4,500–8,000 RSD/m²
- Durability: 20–30 years using quality materials (APP/SBS bitumen membrane or polyurethane membrane)
Warning: Do not apply a new waterproofing layer directly over an old damaged layer without removing it. The new layer will not bond properly and the damage will recur within 1–2 years.
Who Pays for the Repair if the Terrace Leaks into the Apartment Below?
This is a common dispute in residential buildings. The basic rule: a terrace that is "exclusive" — used only by one apartment — is the responsibility of that apartment. A shared flat roof is the responsibility of the residents' association and is funded from common funds. If you are unsure what your ownership deed or building rules state, contact the building management or seek legal advice.
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