Bathroom Renovation Guide for Istanbul's Asian Side

1. Regulations and Permit Process

Under the Istanbul Metropolitan Municipality’s ‘Building and Environment Regulation’, a construction permit (Permit No: 12/2023) is mandatory for bathroom renovations. Changes to plumbing and wall waterproofing must be approved by the municipality.

• •Permit application requires: 1) Project drawings, 2) Technical data sheets for materials, 3) Plumbing layout, 4) Waterproofing details.
• •In historic districts such as Kadıköy and Üsküdar, an additional archaeological assessment may be requested.

2. Design Planning and Budget Allocation

In design, 60‑70% of the existing bathroom footprint is usable. To minimize space loss, consider wall‑built cabinets and sliding doors. Roughly 40% of the budget should cover fixed items like tiles, fixtures, and cabinets; the remaining 60% covers labor, infrastructure and contingencies.

• •Humidity on the Asian side can reach 70%; use waterproof plaster and flexible silicone sealants.
• •If underfloor heating is installed for winter, radiant heating pipes must have at least 30 mm insulation.

3. Infrastructure Works – Plumbing and Electrical

Existing plumbing often consists of old copper pipes; because water pressure on the Asian side is high, upsizing from 15 mm to 20 mm pipe diameter reduces flow issues. Electrical installations must use IP44‑rated switches and sockets suitable for wet environments.

• •A post‑installation water leak test (24‑hour pressurized water) is mandatory.
• •The electrical circuit must be connected to a dedicated breaker as per ‘Bathroom and Toilet’ classification.

4. Waterproofing and Flooring Selection

Waterproofing should consist of a double layer of polyurethane membrane topped with a liquid‑applied acrylic coating. In older Kadıköy buildings where wall thickness is under 12 cm, an additional 10 mm waterproofing board is added.

• •Choose tiles with slip‑resistance class R‑10 and low water absorption (30‑40%).
• •For thermal insulation, install 30 mm stone wool behind walls and use waterproof plaster instead of regular drywall.

5. Finishing, Inspection and Warranty

Upon completion, a municipal inspector must issue a ‘Bathroom Completion Report’. This document triggers the start of the workmanship warranty.

• •Warranty period should be at least 2 years for workmanship and 1 year for material defects not covered by manufacturers, as stipulated in the contract.
• •A user‑satisfaction survey should be conducted within 30 days of hand‑over; any deficiencies must be corrected within 7 working days.

Frequently Asked Questions

Can I start bathroom renovation without a permit?

No. Changes to plumbing and waterproofing require a municipal permit; proceeding without one can lead to fines and mandatory re‑work.

Is water pressure higher in old Asian‑side buildings?

Yes, the network pressure typically ranges between 4‑5 bar, so upsizing pipe diameters helps reduce flow noise and pressure drops.

Which tile class is best for bathroom renovation?

Tiles with slip‑resistance class R‑10 and water absorption below 30% (porcelain) are recommended, especially for high‑traffic wet areas.

How long does the workmanship warranty last?

Güven Kardeşler provides a minimum 2‑year workmanship warranty; defects not covered by manufacturers are covered for 1 year.