Roof waterproofing for schools in Baish

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

Before we start: what we know about Baish

Team note on Baish: 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 Baish sits about 84 m above sea level (SRTM open elevation data).

Baish sits about 84 m above sea level, according to SRTM open elevation data, which places it in a low-lying part of the Jazan region rather than on high ground. For a school roof, this matters because the site is not exposed to the same altitude-driven wind and cold that affect higher towns, but seasonal rainfall still runs off flat school roofs and can pool where drainage is weak. Our survey starts with a check of the roof's falls and outlets so that water is moved away from the membrane rather than left standing on it.

Each fact shapes the work in a practical way. Because the centre is at a modest elevation, we focus on drainage paths and gutter outlets more than on exposure, and we plan the membrane layout around the existing slope of the roof. Liquid roof waterproofing, priced at SAR 8–25 per m², is often suitable for large, continuous school roofs with fewer penetrations, since it forms a seamless layer that can be carried up parapets and around vents. Bitumen membrane, at SAR 15–35 per m², suits roofs that need a heavier, more durable sheet over areas with more foot traffic. Where the roof is also used for insulation, XPS boards at SAR 12–30 per m² can be fitted beneath the waterproofing to reduce heat gain in classrooms below. Cracks in older concrete slabs are sealed by crack injection at SAR 40–120 per metre, and any water tanks on the roof can be lined with tank internal coating at SAR 25–60 per m².

Owners of school roofs commonly avoid several mistakes that cause early failure. They do not wait until ponding or staining appears inside classrooms before calling for work, because small cracks and blocked outlets allow water to spread under the surface. They avoid applying a new coating over a damp or dusty substrate, since adhesion fails without proper preparation. They also avoid leaving parapet edges and pipe penetrations unsealed, as these are the most common routes for leaks. Finally, they plan repairs during school holidays so that the roof can cure without disrupting lessons.

For schools, the larger jobs are planned for weekends and holidays.

Signs that call for roof waterproofing

These are the signs most often linked to roof waterproofing:

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

Causes we see in the field

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

Tools we use in Baish

How the work is done, step by step

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 Baish

Questions from Baish

Mistakes that cost more

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

What you receive

The written output: a quality record with photos and the flood-test result. The report is numbered and can be checked with its verification code.