What is absorption in construction?
Absorption is the uptake of a substance (liquid, gas) or energy (sound, heat) by a material. In construction, absorption plays a role in moisture management, sound insulation and thermal comfort. It is a fundamental concept in building physics.
Types of absorption in construction
Moisture absorption
Building materials absorb water to varying degrees. This is expressed as the water absorption percentage: the weight of absorbed water relative to the dry weight of the material.
| Material | Water absorption (indicative) |
|---|---|
| Brick (facing) | 8–20% |
| Concrete | 3–8% |
| Natural stone (granite) | 0.2–0.5% |
| Natural stone (sandstone) | 3–12% |
| Timber (softwood) | up to 200% (fibre saturation) |
High moisture absorption can lead to frost damage, salt efflorescence and mould growth.
Sound absorption
Acoustic absorption is the ability of a material to absorb sound waves rather than reflect them. Porous materials such as mineral wool, acoustic ceiling tiles and textiles absorb sound well. The absorption coefficient (α) ranges from 0 (total reflection) to 1 (total absorption).
Heat absorption
Dark materials absorb more solar radiation than light materials. This affects the thermal comfort and energy performance of a building.
Application
- Cladding — choosing materials with low moisture absorption prevents damp problems
- Acoustics — absorptive materials are used in ceilings and walls to reduce reverberation
- Solar energy — solar collectors absorb heat for hot water production
Related terms
- Insulation
- Building physics
- Sound insulation
- Moisture
- Brick
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