When we see a wall “sweating,” we tend to blame it on humidity in the air. In reality, in most cases, the problem originates much deeper down, in the ground on which the building stands. This is where a slow physical process—called capillary rise—begins, which can damage masonry and plaster over time.
This extremely common phenomenon follows the same physical principle that allows a sponge to absorb water or sap to rise up the trunk of a plant. It occurs when water in the soil rises through building materials by seeping through the tiny pores in bricks, stones, and mortar, carrying mineral salts with it that, as they evaporate on the wall’s surface, cause efflorescence, plaster spalling, and progressive deterioration of the masonry.
The type of soil on which a building is constructed has a significant impact on this issue. Clay soils, characterized by very small pores and a greater capacity to retain water, are more conducive to capillary rise. Conversely, sandy soils, thanks to their greater permeability, allow for faster drainage of water, reducing the risk of standing water in contact with the foundations. For this reason, the design of a building must include proper management of groundwater and drainage systems suited to the soil’s characteristics. Rising damp, in fact, is not merely an aesthetic issue: a stain, peeling paint, or a musty odor in the basement can, over time, reduce the durability of plaster, diminish the performance of insulation materials, and create conditions conducive to mold growth.
Taking action only after a problem has become apparent often means dealing with more complex and costly repairs. For this reason, in new construction and building renovation projects, it is essential to limit water accumulation in contact with underground structures and reduce hydrostatic pressure. To achieve this, Tenax has developed DP1, a drainage composite consisting of a high-density polyethylene (HDPE) membrane bonded to a polypropylene filter geotextile that prevents fine soil particles from clogging the drainage system, ensuring its efficiency remains constant over time. When installed to protect foundations and retaining walls, DP1 creates a drainage layer that collects and channels water from the soil toward drainage systems while simultaneously protecting the waterproofing membrane from mechanical stresses generated by the soil during backfilling and throughout the structure’s lifespan.
Compared to traditional drainage systems made with sand and gravel, this system offers several advantages: it requires less excavation, reduces the need to transport quarry material, and maintains its drainage capacity over time thanks to the geotextile, which limits the risk of clogging. Furthermore, when used against foundation walls, DP1 helps reduce the hydrostatic pressure exerted by water on the waterproof lining. This means reducing the risk of water infiltration and preserving the functionality of basements, garages, and other underground spaces over time.