Roof waterproofing for duplexes in Alzulfi

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

Before we start: what we know about Alzulfi

Team note on Alzulfi: 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.. The centre of Alzulfi sits about 615 m above sea level (SRTM open elevation data).

Main roads in or near Alzulfi: King Fahd Road, Sheikh Ibn Baz Square, King Salman Road.

Picture a family who owns a duplex in Alzulfi, with one unit they live in and another they rent out. Their main worry is the roof. Each rainy season they notice a faint stain on a ceiling, or a patch of damp near the stairwell, and they wonder whether it is a small problem or the start of something costly. Like many owners of two-unit homes, they split the repair decision between themselves, which means the roof often goes unattended until a leak becomes hard to ignore.

The local facts matter here. The centre of Alzulfi sits about 615 m above sea level, so the town is in the highlands rather than on the coast, and roofs there face their own mix of sun, temperature swings and occasional heavy rain. For a duplex, that means the roof covers two households, so a leak can damage both units at once and affect shared finishes. Prices for roof work are listed per square metre, with liquid roof waterproofing at SAR 8–25 per m² and bitumen membrane at SAR 15–35 per m². Because the two options sit at different points on that range, the owner should compare the roof's size, its current condition and the expected use before choosing. A roof that is simply ponding in places has different needs from one with cracks at its edges.

A practical order helps. First, walk the roof after rain and mark every damp spot, crack and loose edge, then check the ceilings below for matching stains. Second, decide whether the roof needs a full new layer or a repair, since liquid coatings suit smooth surfaces while bitumen membrane suits a larger, more uniform area. Third, where cracks run through the surface, plan for crack injection, priced at SAR 40–120 per metre, before the coating goes on. Fourth, collect at least two written quotes that state the area measured in square metres so they can be compared fairly. Finally, schedule the work outside the peak rainy weeks and keep the receipts and a dated photo record, which will be useful for both owners and any future tenant.

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 Alzulfi, it is a good moment to talk to the team:

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

The most common causes

• Cracks in the roof slab — we check this before anything else.
• Damaged waterproofing around tank and AC bases.
• Wrong falls towards the drains — we check this before anything else.

How we choose the tool in Alzulfi

The steps in order

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.

Facts and costs — Alzulfi

Questions from Alzulfi

What we advise against

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

What you receive

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