Roof waterproofing for duplexes in Khafji

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

Before we start: what we know about Khafji

Main roads in or near Khafji: King Abdullah Road. Team note on Khafji: 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..

Khafji is about 2 km from the sea coast (OpenStreetMap). The centre of Khafji sits about 9 m above sea level (SRTM open elevation data).

Consider a duplex owner in Khafji who has noticed a damp patch spreading across the ceiling of the upper flat after a windy evening. The roof is shared between two households, so it is unclear who should pay, and the owner wants a fix that lasts without repeated visits. Like many homes in the town, the building is not far from the coast, and the owner has heard that the roof needs attention before the problem reaches the rooms below.

The local facts matter here. The centre of Khafji sits about 9 m above sea level, so rainwater runs off the roofs and does not pool in the way it might in a low-lying district, but the roof surface still needs a continuous, sealed layer to stop water finding its way into joints. Khafji is also about 2 km from the sea coast, which means salt-laden air is present and can wear down exposed surfaces and sealants over time. For a duplex, these conditions favour a waterproofing system chosen for exposure, with clear responsibility agreed between the two owners before work begins.

Start by inspecting the roof surface together with both households and marking every crack, blister and joint that shows wear. Next, repair the cracks, which can be treated by crack injection at SAR 40–120 per m, so that the substrate is sound before any coating goes on. Then choose the system: liquid roof waterproofing at SAR 8–25 per m² suits many flat roofs, while bitumen membrane at SAR 15–35 per m² offers a heavier layer where movement is expected. Where thermal protection is also wanted, XPS boards at SAR 12–30 per m² can sit beneath a protective finish. Agree the scope and cost split in writing, book the work, and schedule a check after the first heavy rain.

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

Signs that call for roof waterproofing

If you notice one of these signs in Khafji, it is a good moment to talk to the team:

• The old waterproofing is cracking
• Water pooling on the roof
• Stains on the top-floor ceiling after rain

The most common causes

• Cracks in the roof slab.
• A common cause: wrong falls towards the drains.
• Damaged waterproofing around tank and AC bases.

Tools we use in Khafji

From the first visit to the report

1. Survey: Falls, drains and the condition of the old layer are recorded.
2. Preparation: Cleaning and repairs before any new layer.
3. Primer: The base coat that the system needs.
4. Waterproofing layers and details: Corners, upstands and bases get their own detail.
5. Flood test: The roof is flooded and checked before it is covered.

Quick comparison: facts and costs in Khafji

Short answers for Khafji

What we advise against

• Ignoring the tank bases
• Covering the waterproofing before the flood test

What you receive

You receive: a quality record with photos and the flood-test result, in a technical report with a verification code.