Water tank waterproofing for duplexes in Unaizah

Prepared by the technical team · editorial review · last updated 13 November 2026 · Sources

Why water tank waterproofing differs in Unaizah

The centre of Unaizah sits about 667 m above sea level (SRTM open elevation data). Team note on Unaizah: Kashf teams serve this city and its nearby districts with the same documented inspection standard: device-based leak detection without demolition, a written report, and a clear scope before any work begins..

Picture a family who owns a duplex in Unaizah. The upper and lower units share a rooftop water tank, and over the past few seasons they have noticed damp patches on a wall, a faint stain near the tank stand, and a musty smell in the lower bathroom. They are not sure whether the problem comes from the tank, the roof, or the walls, and they want a clear plan before they spend money on repairs that might not address the real cause.

Unaizah sits at about 667 m above sea level, so the town is not in the coastal humidity that drives moisture problems in lower-lying cities, but seasonal rain, sun-driven expansion of roof surfaces and the daily cycle of filling and draining a tank all still put stress on joints and coatings. For a duplex, this matters because a leak from one tank can reach both units, and an owner has to decide which surfaces to treat. A roof and tank that are fixed together, rather than piecemeal, usually avoids repeating the same job. Typical rates in the local market show a wide range: liquid roof waterproofing runs from SAR 10–25 per m², a bitumen membrane from SAR 15–35 per m², and tank internal coating from SAR 25–55 per m². Ask for quotes that state the area and the surface being treated, so you can compare like with like.

Start by inspecting the tank and roof together. Drain the tank, look for hairline cracks and check the joints, then trace any wet marks down the wall to see whether the water is entering from above or from a pipe. Next, mark each crack and measure its length, because crack injection is priced per metre at SAR 40–115 per m, and this gives you a firm figure to discuss. Clean and dry the surfaces before any coating is applied, since a coating on a damp base will fail early. Then choose the system: a tank internal coating for the water side, and liquid or membrane waterproofing for the roof. Where a bathroom or wall shows damp, bathroom waterproofing at SAR 15–40 per m² may be needed. Finally, arrange a short check after the first full fill cycle to confirm that the repairs have held before you close the job.

In a duplex, the two floors often share lines, so tests are done floor by floor.

Signs that call for water tank waterproofing

The following signs are worth checking before they grow:

• Unusual colour or taste in the water
• A tank that leaks after testing
• Deposits and flaking inside the tank

The most common causes

• Construction joints.
• Damaged old coating.
• Cracks in the walls or floor — we check this before anything else.

Tools and methods, and when we use them

From the first visit to the report

1. Emptying and ventilation: The tank is emptied and ventilated before entry.
2. Cleaning and preparation: Loose material is removed down to a sound surface.
3. Crack treatment: Active cracks are treated first.
4. Coating layers: A material intended for drinking-water tanks is applied.
5. Disinfection and fill test: The tank is disinfected and the level is monitored after filling.

Quick comparison: facts and costs in Unaizah

Short answers for Unaizah

What we advise against

• Using a material that is not intended for drinking water

What you receive

You receive: the material name, its batch number and the fill-test result, in a technical report with a verification code.