Professional application of external basement waterproofing

After planning (evaluation of water load, clearance of details etc.) the waterproofing works can begin. For this purpose mainly polymer-modified bitumen thick coatings (PMBC) are used. This type of material has proven to be efficient in practice for the last 40 years. Their main advantages: crack-bridging and resistance to pressure water, i.e. high reliability, trowel-grade and non-sag consistency, jointless and seamles cold-applied membrane in one body, for walls and floor, without preliminary render layer, suitable on slightly damp surfaces, easy application, practice-oriented execution of all detail points and in all points confirmed by officicial approvals. A tanking all around the foundations (walls and concrete slab) is necessary so that the buildings are protected from water load in all parts.

Step by step


    1. Remove dirt, water-repellent substances and all adhesion-impairing particles, for ex. cement laitance with a diamond rotative disc. The outer angle of the concrete slab forepart must be rounded.


    2. The groove area (angle between basement wall and concrete slab) is cleaned and moistened (dull-moist) before a bonding layer of the watertight mortar weber.tec 933 mixed in brush consistency is applied.


    3. Apply weber.tec 933 mixed in trowel consistency as groove mortar "wet-on-wet" on the bonding layer with the preformed rounded trowel "big size" weber.sys Hohlkehlenschlitten. Thus a 90° angle is excluded and a uniform layer thickness for the waterproofing is obtained.


    4. Use the bitumen primer weber.tec 901 diluted 1 : 10 with water for obtaining a dust binding effect and a unifrom substrate porosity.


    5. Separation joints between buildings are waterproofed with the sealing tape weber.tec Superflex B 240 E (with end T-piece). Its fleece-backed sides are bonded on both joint sides oand covered with the same bitumen material used for the waterproofing of main surfaces.


    6. Penetrations (for ex. sewage water pipes) are water-proofed with a special system (for ex. Doyma or a loose/flange system) depending on water load and inte-grated with the water-proofing layers on walls.


    7. In case of water pressure under the lean concrete (i.e. beneath the floor concrete slab), the connection with the wall waterproofing is done at the internal angle with the slab.


    8. In case of connection water-impermeable concrete slabs the external wall waterproofing is applied till to the forepart of the concrete slab at least 15 cm downwards.


    9. Socket part of facades with insulation boards (splash water area): the waterproofing is applied upwards up to the upper side of insulation boards. The specific socket insulation boards are bonded onto the dry waterproofing.


    10. Socket part of facades with render: apply the 2-comp. reactive water-proofing slurry weber.tec Superflex D 2 or the 2-comp. reactive, thick and quick-setting water-proofing coating D 24 up to approx. 20 cm under the final earth level. The bitumen layer (used for basement walls) will overlap the socket waterproofing (D 2 or D 24) up to the upper earth level. Above the earth level apply the stipple coat.


    11. Apply the quick-setting stipple coat weber.san 951 S full-surface onto the D 2 or D 24 layer. After drying apply the water-proof render weber.tec 934 in a thickness of 15 mm, rule and after initial setting smooth it.


    12. After drying of the primer first apply a scratch layer of the 2- comp. lightweight bitumen proofing thick coating weber.tec  Superflex 10.


    13. Apply the first layer of weber.tec Superflex 10 with the special notched trowel weber.sys Schichtdickenkelle which allows the same layer thickness whatever the hand angle is. The layer thickness depends upon the water load (non- pressure water or pressure water). In case of pressure water insert the woven glass fiber mesh weber.sys 981 onto the fresh first layer.


    14. Apply the second layer weber.tec Superflex 10 as soon as the first one cannot be damaged.


    15. Apply the bitumen in groove form along angles, for ex. light wells.


    16. Check the minimum dry layer thickness with the Weber graduated tool Schichtdickenmesser: 3 mm in case of non-pressure water (W1.-E ) and 4 mm in case of pressure water (W2.1-E).



    17. After full drying of waterproofing layers insulation boards or drainage/protection foils can be installed. Thus damages due to the earth-filling of excavation will be avoided. For checking the final state of drying make a test on a stone sample placed in the building site at the beginning of waterproofing works.


    18. After full drying of waterproofing layers install the drainage mat weber.sys 983 on the wall and fix it with the metal rail weber.sys 983 A at the upper side of the bitumen layers. At the wall bottom the foil is connected with the circular drainage. Afterwards it is allowed to backfill the excavation.


    19. Alternatively insulation boards can be glued either dotwise or full-surface with the same bitumen material on the dry water-proofing layer.