Underground & Tanking

The ingress of water or dampness in underground premises is a challenge for inhabitants and building constructors that needs to be considered in all stages of the building process. There are many challenges to face as there are many possible sources of unwanted moisture. Three factors can result from groundwater seepage through the surrounding walls of a building: 

  • The water table, whose level may vary (rainfall, or high water levels in neighbouring watercourses), causing water to rise above the lowest level of the building underground. 
  • Underground sources of water can project massive quantities of water against the outer walls of buildings, both above and below ground.
  • Damp capillary rise, leading to water rising walls up to the level of the residential quarters of a building when in contact with and under the pressure of water-laden soil.



The situations above can be remedied by adequate waterproofing or water-protection systems. At BMI, we are experienced in working on highly complex underground and tanking projects with a broad range of solutions: bitumen, synthetic, and liquid to answer any waterproofing need:

Underground below water level

All the voids in the soil are filled with water, putting the construction walls under pressure. The waterproofing is provided by tanking techniques. Discover our tanking systems: 

  • Teranap 431 TP system is the best solution for tanking and underground structures, exposed to high water pressure. 
  • Parafor M4S is a suitable solution for low-rise buildings and medium to low water pressure. 

Underground above water level

The land is not saturated in water, and water is in contact with the construction walls without exerting pressure on them; the action of water is limited to movement by capillary attraction. The protection of the construction will then require:

Surface treatment of underground walls:

  • Adeti Premium self-adhesive bitumen membrane for dry areas
  • Fondafor / Fondafor S elastomeric bitumen membrane for exterior waterproofing of underground walls
  • Fondacoat is used as a concrete protective coating. (e.g. foundations and below grade structures above the water level​​​​)

Damp course to cut of damp capillary rise at the top of the foundation walls:

  • Fondaply 2 SBS self-adhesive bituminous membrane for damp-proof courses for waterproofing of underground walls in concrete
  • Fonda Bande bituminous strip used as damp proof course 

Find more about protection and drainage boards for underground walls:

For your specific underground and tanking projects, please contact our technical team. Our experienced team will accompany you from the design phase to the finalization of the project providing all technical designs, documentations with site surveys,, and supervision.