The difference in the applicability of rock wool boards of different densities in exterior wall insulation is mainly reflected in the matching degree between material properties and building requirements. It is necessary to comprehensively consider multiple factors such as building structure, climate conditions, and energy-saving goals to achieve a balance between thermal insulation performance, mechanical strength, and economy.
The density of rock wool board is directly related to the tightness of its internal fibers, and this characteristic will significantly affect the thermal conductivity and thermal insulation performance of the material. Generally speaking, the internal fibers of rock wool boards with lower density are arranged more loosely, and the air pores formed are larger. They may have relatively low thermal conductivity under normal temperature conditions, and theoretically have better thermal insulation effects. However, when this structure is subjected to external forces, such as extrusion during construction or wind pressure and self-weight during long-term use, it is easy to be compressed and deformed, resulting in the destruction of air pores, and the actual thermal insulation performance may decrease over time. Therefore, rock wool boards with lower density are more suitable for building scenarios with higher requirements for thermal insulation performance but relatively low requirements for mechanical strength, such as the insulation of low-rise residential buildings or internal non-load-bearing walls, and special attention should be paid to avoid excessive compression during construction to maintain its initial thermal insulation performance.
Rock wool board with higher density presents the opposite characteristics. Its internal fibers are closely arranged, the air pores are smaller, the overall mechanical strength of the material is significantly improved, and the wind pressure and impact resistance are stronger, which can better meet the requirements of structural stability in high-rise buildings or exterior wall insulation systems. However, higher density may lead to a slight increase in thermal conductivity, and the insulation performance is slightly inferior to low-density products at the same thickness. However, by appropriately increasing the thickness of the board, high-density rock wool board can still meet higher energy-saving standards. At the same time, with its excellent mechanical properties, it is more suitable for use in areas that are easily affected by external forces, such as the first floor of the building, balcony, and air conditioning unit installation area. These locations require materials to have stronger impact resistance to avoid damage to the insulation layer due to daily collisions.
Climate conditions are an important basis for selecting the density of rock wool board. In cold areas, the main goal of exterior wall insulation is to reduce heat loss, and the requirements for insulation performance are more stringent. Therefore, it may be more inclined to use rock wool board with moderate density, which can not only ensure a certain mechanical strength, but also achieve efficient insulation through a reasonable pore structure. For example, in northern regions with long winters and extremely low temperatures, if rock wool boards with too low density are used, the insulation layer may have a "thermal bridge" phenomenon due to compression and deformation of the material, affecting the overall energy-saving effect; while boards with too high density may increase the thermal conductivity and need to increase thickness to compensate for the insulation performance, thereby increasing construction costs and wall weight. In hot and humid areas, in addition to insulation requirements, the air permeability and moisture resistance of rock wool boards must also be considered. Boards with moderate density can effectively block heat transfer and allow water vapor to diffuse due to their reasonable internal pore structure, reducing the accumulation of condensed water in the insulation layer and reducing the risk of mold growth and material corrosion.
Building height and body coefficient will also affect the choice of rock wool board density. The exterior walls of high-rise buildings are subject to greater wind pressure, especially in typhoon areas or coastal areas. High-density rock wool boards can better resist strong wind loads due to their higher wind pressure resistance and avoid safety hazards caused by the shedding of the insulation layer. For buildings with complex shapes, such as exterior walls with bay windows, decorative lines and other structures, more cutting and splicing are required when installing rock wool board. Due to its greater hardness, the boards with higher density are easier to maintain their shape during processing and reduce edge damage, thereby ensuring the integrity of the insulation system. For the exterior walls of low-rise buildings or flat structures, the requirements for wind pressure and mechanical strength are relatively low. Rock wool boards with lower density can be selected based on energy-saving calculations to reduce material costs.
The adaptability of the construction process is also a factor that cannot be ignored. Rock wool boards of different densities perform differently in the construction links such as pasting and anchoring. Boards with lower density are softer in texture and are easier to fit with the wall base when pasted with adhesives. They are especially suitable for walls with higher surface flatness. However, it is necessary to control the amount of adhesive and the uniformity of application to avoid insufficient bonding area due to compression deformation of the board. Boards with higher density require stronger bonding and anchoring forces. During construction, it may be necessary to increase the number of anchor bolts or use longer anchor bolts to ensure that the board is firmly connected to the base. In addition, when performing surface construction, such as applying plastering mortar or installing decorative surface layers, high-density rock wool board has a smoother surface and higher hardness, which is conducive to improving the construction quality of the surface layer and reducing the occurrence of problems such as cracks.
Economic analysis also plays an important role in the selection of rock wool board density. Generally speaking, the higher the density of rock wool board, the higher the production cost. Therefore, on the premise of meeting the requirements of thermal insulation and mechanical properties, choosing a board with a suitable density can optimize the project cost. For projects with high energy-saving requirements but limited budgets, it may be necessary to weigh the density and thickness, and choose a rock wool board with a slightly lower density but a larger thickness to reduce the unit price of materials while ensuring the thermal insulation effect. For high-end buildings or projects with extremely high safety requirements, it is better to increase the cost and choose a high-density rock wool board to ensure the long-term stability and reliability of the thermal insulation system. In addition, the later maintenance cost must also be considered. If the low-density rock wool board needs to be replaced in advance due to performance degradation, additional costs will be added. Although the high-density board has a higher initial investment, it has a longer service life and the comprehensive cost may be more advantageous.
The difference in the applicability of rock wool boards of different densities in exterior wall insulation is essentially a dynamic balance between material performance and building requirements. The selection should be based on the climate zone, structural form, functional use, construction conditions and budget constraints of the building. Through detailed thermal and mechanical calculations, the density of rock wool boards that can meet current energy-saving standards and safety regulations and achieve the best cost-effectiveness should be determined. At the same time, with the development of construction technology and the improvement of environmental protection requirements, the production process of rock wool boards may be further optimized in the future, so that it can achieve a better match between thermal insulation performance and mechanical strength in different density ranges, providing more flexible options for exterior wall insulation systems.
