# How to Waterproof a Bathroom? Solutions Without Demolition and Technical Errors
Bathroom waterproofing is the most critical stage of bathroom renovation. Incorrectly applied waterproofing leads to water leakage to downstairs neighbors, moisture in walls, mold formation, and structural damage. In this guide, we address the waterproofing techniques we use, solutions without demolition, and the most common technical errors from a master's perspective when doing bathroom renovation in Kadıköy, Bakırköy, Beşiktaş, Şişli, Üsküdar, and all Istanbul districts.
Importance of Bathroom Waterproofing: Why Critical?
The bathroom is the part of the home that uses the most water. Walls, floors, and ceilings are constantly in contact with water and vapor. Without waterproofing:
1. Water Leakage: Water leakage occurs to downstairs neighbors
2. Moisture and Mold: Moisture accumulates in walls, mold forms
3. Structural Damage: Reinforcement (steel) corrosion begins in reinforced concrete structures
4. Health Risks: Mold and fungus lead to respiratory diseases
5. Costly Repairs: Waterproofing errors may require the entire bathroom to be redone
Master's Note
Bathroom waterproofing should be done in accordance with TS 11758-1 standard. If application is not done in accordance with this standard, insurance companies may not cover water leakage damages.
Materials Used in Bathroom Waterproofing
In bathroom waterproofing, different materials are used in different layers. We apply this systematic approach:
1. Polyester Fabric-Reinforced Bitumen-Based Membrane
Polyester fabric-reinforced bitumen-based waterproofing membrane is the main material for bathroom waterproofing.
Membrane Characteristics
- Thickness: 3-4 mm
- Waterproofing: 100% (TS 11758-1 compliant)
- Flexibility: Adapts to cracks
- Adhesion: Adhered to floor and walls
Membrane Application Technique
Step 1: Surface Preparation- Floors and walls are cleaned
- Imperfections are removed
- Wet surfaces are dried
- Bitumen primer is applied to floors and walls
- Primer ensures membrane adhesion
- Drying time: 2-4 hours
- Membrane panels are adhered to floors and walls
- Extended 20 cm upward on walls (180 cm in shower enclosure area)
- Extra layer applied at corners and joints
- Adhesion: Special bitumen adhesive or by heating (torch-on)
Master's Note
In membrane application, corners and joints are the most critical points. Extra layer (overlap) must be applied in these areas. Otherwise, water leakage starts from these points.
2. XPS Foam Insulation
XPS foam provides both thermal and moisture control.
XPS Foam Characteristics
- Waterproofing: Waterproof thanks to closed-cell structure
- Thickness: 3-5 cm on bathroom floor
- Thermal conductivity: Lambda value 0.030-0.035 W/mK
XPS Foam Application
XPS foam is placed under floors and walls. Its functions:
- Prevents floor and wall coldness
- Reduces condensation risk
- Prevents heat loss
In old buildings in Kadıköy and Bakırköy, XPS foam usage is especially important because floors are cold.
3. Waterproof Screed (Special Additive Screed)
Waterproof special additive screed is applied to bathroom floor.
Screed Characteristics
- Additive: Waterproofing additive (3-5%)
- Thickness: Minimum 4 cm
- Curing Time: 7 days (by wetting with water)
Master's Note
In screed application, waterproofing additive must be used. Normal screed allows water passage and reduces the effectiveness of the insulation system.
4. Ceramic Underlayment Insulation Additive
Waterproofing additive is added to ceramic adhesive. This additive:
- Provides an additional protection layer
- Prevents water passage through joints
- Prevents mold formation
Waterproofing Solutions Without Demolition
In some cases, bathroom waterproofing can be done without demolition. These solutions:
1. Insulation Over Existing Ceramics
If existing ceramics are sound, waterproofing can be applied over them.
Application Technique
Step 1: Ceramic Surface Preparation- Ceramics are cleaned
- Joints are cleaned and filled
- Surface is roughened (abraded)
- Polyurethane or acrylic-based waterproofing coating is applied
- Applied in 2-3 coats
- Drying time: 24 hours per coat
- New ceramics are installed over waterproofing coating
Master's Note
Solutions without demolition are temporary solutions. For permanent solution, membrane must be applied by doing demolition.
2. Shower Enclosure Underlayment Insulation
Water accumulation under shower enclosures leads to water leakage. In shower enclosure underlayment insulation:
Shower Enclosure Underlayment Insulation System
Step 1: Floor Slope- Floor under shower enclosure is made with 2% slope toward toilet
- Water flows toward toilet side
- Floor and walls under shower enclosure (up to 180 cm height) are covered with membrane
- Extra layer applied at corners
- Drain (outlet) is placed under shower enclosure
- Drain perimeter is insulated with special insulation tape
In luxury apartments in Beşiktaş and Şişli, shower enclosure underlayment insulation is especially important.
Most Common Technical Errors in Bathroom Waterproofing
In our 20 years of experience, we frequently see the following errors in bathroom waterproofing:
Error 1: Insufficient Membrane Wall Height
Incorrect Application: Membrane is extended only 10-15 cm upward on walls. Correct Application: Membrane should be extended minimum 20 cm upward on walls. Should be extended up to 180 cm height in shower enclosure area.Master's Note
If membrane height is insufficient, water leakage occurs from wall joints. This error is the most common waterproofing error.
Error 2: Not Applying Extra Layer at Corners and Joints
Incorrect Application: Membrane is applied flat at corners. Correct Application: Extra layer (overlap) should be applied at corners and joints. At corners, membrane should be cut in L shape and applied.Error 3: Not Using Waterproofing Additive in Screed
Incorrect Application: Normal screed is applied, waterproofing additive is not used. Correct Application: Waterproofing additive must be added to screed.Error 4: Installing Ceramics Directly on Membrane
Incorrect Application: Ceramic adhesive is applied directly on membrane. Correct Application: Protective layer (non-woven geotextile) should be applied on membrane first, then screed should be done.Error 5: Insufficient Drain (Outlet) Insulation
Incorrect Application: Drain perimeter is uninsulated. Correct Application: Drain perimeter should be insulated with special insulation tape and membrane.
Bathroom Waterproofing Costs: 2026 Current Prices
Bathroom waterproofing costs in Istanbul vary according to bathroom size and application type.
Complete Waterproofing (Membrane + Screed + Insulation)
| Bathroom Size | Premium Segment | Standard Segment |
| 4-5 m² | 15,000 - 25,000 TL | 10,000 - 18,000 TL |
| 6-8 m² | 25,000 - 40,000 TL | 18,000 - 30,000 TL |
| 10 m²+ | 40,000 - 60,000 TL | 30,000 - 45,000 TL |
Partial Waterproofing
- Only Membrane Application (5 m²): 8,000 - 15,000 TL
- Shower Enclosure Underlayment Insulation (2 m²): 5,000 - 10,000 TL
- Coating Without Demolition (5 m²): 6,000 - 12,000 TL
In districts like Kadıköy, Bakırköy, Beşiktaş, Şişli, labor costs are higher.
Frequently Asked Questions (FAQ)
Is bathroom waterproofing mandatory?
Yes, bathroom waterproofing is mandatory according to TS 11758-1 standard. Bathroom renovation cannot be done without waterproofing.
How many years is waterproofing guaranteed?
Correctly applied waterproofing is guaranteed for 10-15 years. However, this depends on application quality and usage conditions.
What should I do if water leakage occurs?
In case of water leakage, water source should be cut first. Then, contact should be made with a professional renovation company. Insurance company should be notified.
Are solutions without demolition permanent?
Solutions without demolition are temporary solutions (2-5 years). For permanent solution, membrane must be applied by doing demolition.
Conclusion: Get Professional Support
Bathroom waterproofing is a technical process requiring expertise. Incorrect application leads to costly repairs. With 20 years of experience, we offer bathroom waterproofing service in Kadıköy, Bakırköy, Beşiktaş, Şişli, Üsküdar, and all Istanbul districts.
By booking a free site visit appointment, you can get detailed waterproofing analysis and cost proposal for your bathroom. Free Architectural Site Visit Line: 0501 022 33 75
