A plinth is the lowest, often slightly protruding section of a facade or wall, forming the transition between the foundation and the rest of the wall. The plinth protects the masonry from splashing rainwater, ground moisture and mechanical damage. On houses, the plinth is usually 30-60 cm high and sometimes finished in a different material or colour than the rest of the facade.
Plinth vs. skirting board
| Term | Location | Function |
|---|---|---|
| Plinth | Exterior facade | Protects bottom of facade from moisture/impacts |
| Skirting board | Interior wall, floor edge | Covers the floor-wall gap |
Types of plinths
| Type | Material | Features |
|---|---|---|
| Brick plinth | Different brick type/colour | Classic, visible contrast with facade |
| Concrete plinth | Cast or precast concrete | Strong, smooth, common in commercial buildings |
| Natural stone plinth | Bluestone, granite | Durable, stately, expensive |
| Rendered plinth | Masonry + waterproof render | Sleek appearance |
| Coated plinth | Masonry + water-repellent coating | Invisible, good protection |
Maintaining and protecting a plinth
Refurbishing an existing plinth
1. Remove loose paint/render — Scrape and brush
2. Repair joints — Remove damaged mortar and repoint
3. Primer — Moisture-resistant
4. Apply plinth paint — Specifically for exterior use, water-repellent, breathable
Rising damp and the plinth
The plinth is the most vulnerable part for rising damp: groundwater that travels upward through masonry via capillary action. Signs include:
- White deposits (salts) on the brickwork
- Flaking paint
- Damp interior walls on the ground floor
Solution: Injection with a water-repellent agent (silicone/silane) at approximately 15 cm above ground level.
Common mistakes
- Ground level too high against the plinth — Keep at least 15 cm between ground level and the top of the plinth
- Non-breathable paint — Moisture can’t evaporate, worsening the problem
- Backfilling with clay — Retains moisture against the facade
Related terms
- Facade
- Skirting board
- Foundation
- Bond pattern
- Mortar joints
- Cavity wall