Key points
- Expansive soils swell when wetted and shrink when dried; a 2025 regional review puts them at about 37% of Saudi Arabia's area.
- Sabkha can collapse when wetted and is corrosive; it is widespread on the Red Sea and Gulf coasts.
- Rising damp is usually linked to a missing or failed damp-proof course; water pooling at the wall base makes it worse.
- Slope yards away from walls (ICPI: at least 1.5% for paved surfaces), and keep AC and downpipe outlets away from foundations.
Written for:OwnerContractor
Water that collects around a house does not stay on the surface: it soaks into the soil under the foundations and rises in the base of walls. In our homes its sources are often not just rain but garden irrigation, AC condensate, yard washing water and roof downpipes.
1) Why it matters
- Expansive soils: clays that swell when wetted and shrink when dried, covering about 37% of the Kingdom's area, with damage ranging from minor cracks to large movements of footings1. Intermittent irrigation next to a wall means wetting and drying cycles under the foundation.
- Sabkha: on the Red Sea and Gulf coasts, it may collapse when wetted as its cementing materials dissolve, and it is corrosive2.
- Rising damp: usually linked to a missing or weak damp-proof layer in walls or floors3; water pooling at the wall base worsens it and shows as efflorescence and peeling. See damp walls.
- Mold: the key to mold control is moisture control4.
For details: soil and foundations.
2) Common sources and fixes
| Source | Problem | Practical fix |
|---|---|---|
| Garden and tree irrigation | Constant wetting of soil against the wall | Move planters and drip lines away from walls, and avoid large-rooted trees against the building (practical advice) |
| AC condensate | Daily dripping at the same spot for years | Keep AC drip pans clean and drain lines unobstructed, and make the ground slope away from the foundation so water does not collect around it4 |
| Roof downpipes | Concentrated rain dumped at the wall base | Extend the outlet away from the wall or into a drainage system (practical advice) |
| Yard falls | Washing and rain water run back to the wall or thresholds | At least 1.5% fall on paved surfaces5, directed away from the building. See yards and interlock |
| Buried pipe leaks | Unseen water under floors | The meter test6. See leak detection |
3) A checklist around your house
- Walk round the house after irrigation or rain: where does water collect?
- Is the base of the outside walls damp or white with salts?
- Where do AC condensate and downpipes discharge?
- Any new cracks in paths around the house or in walls near the ground? Widening cracks need an engineer. See concrete cracks.
- Are the pavers or tiles around the house sloping down towards the wall?
When to call an engineer: diagonal or widening wall cracks, doors and windows starting to stick, or visible floor settlement: these can be foundation-related and are not fixed by patching.
Sources
The number next to a statement points to its source in this list. Sources back the general information; anything marked “practical advice” is editorial experience, not a quoted source. Anything that affects safety, structural design or electrical installations needs a licensed professional, and in Saudi Arabia the binding reference is the Saudi Building Code.
- 1Geotechnical characterization of expansive soils in Saudi Arabia: A regional review — Journal of Umm Al-Qura University for Engineering and Architecture (Springer)
- 2A review on the characteristics of sabkha soils in the Arabian Gulf Region — Arabian Journal of Geosciences (Springer)
- 3Diagnosing the causes of dampness in buildings — BRE (Building Research Establishment)
- 4A Brief Guide to Mold, Moisture and Your Home — U.S. Environmental Protection Agency (EPA)
- 5Tech Spec 2: Construction of Interlocking Concrete Pavements (rev. February 2020) — Interlocking Concrete Pavement Institute (ICPI) — copy hosted by ORCO Block & Hardscape
- 6Fix a Leak Week — How to check for leaks (meter test, toilet dye test) — U.S. EPA — WaterSense
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This guide is for general information and planning, based on standards and technical guides. Standards are revised periodically; in Saudi Arabia the binding reference is the Saudi Building Code and the instructions of the competent authorities. For design and execution, use a licensed engineer or technician. Found an error? Tell us.