What is the downside of rockwool?

The core disadvantages of rock wool mainly lie in three aspects: construction and health risks, poor water resistance, and high bulk density, which directly affect its installation convenience and applicable scenarios.
1. High Construction and Health Risks
This is the most prominent disadvantage of rock wool, which has a great impact on construction workers and subsequent maintenance.
Fibers are easy to fall off: Rock wool is composed of ultra-fine glass fibers. The fibers are prone to scattering during cutting or handling. Inhalation may irritate the respiratory tract, and long-term exposure poses health risks.
Protection is required during construction: Professional masks, gloves, and protective clothing must be worn, which increases construction costs and operational complexity. In addition, fibers sticking to the skin can easily cause itching.
2. Poor Water Resistance
The water-absorbing property of rock wool limits its application in humid environments.
Easy to absorb water and get damp: Rock wool itself is not waterproof. Once it comes into contact with water or is in a high-humidity environment, it will absorb water quickly, leading to a sharp decline in thermal insulation performance.
Easy to deteriorate after getting damp: After absorbing water, rock wool may soften, become moldy, or even suffer structural damage. Additional waterproofing treatment is required; otherwise, it cannot be used in scenarios such as external walls and underground projects.
3. High Bulk Density, Inconvenient Installation
Compared with other lightweight thermal insulation materials, the physical properties of rock wool increase the difficulty of construction.
Heavy self-weight: Under the same thermal insulation effect, the bulk density of rock wool is much higher than that of materials such as extruded boards and polystyrene boards, which places higher requirements on the load-bearing capacity of walls or roofs.
Difficult to cut and fix: It is relatively brittle and prone to cracking during cutting. Moreover, special anchors are needed for fixing, resulting in low installation efficiency and may increase the overall weight of the building.