Internal renovation of basements with flexible waterproofing mortars

Due to the growing interest in the preservation of valuable building substance, the importance of renovation of basement rooms is constantly growing. A prior inventory and an analysis of the damages are prerequisites for a successful renovation. Investigations of the moisture and salt content on internal and external walls provide important findings on the causes of the damage. Based on these data, the renovation concept is drawn up.

Step by step


    1. Ground damp is rising through the capillaries of masonry resp. extending hori-zontally. A horizontal or vertical damp-proof barrier is defective or not existing.


    2. Prerequisite for a successful renovation is a precise analysis of the building conditions.


    3. Remove the old render at least 80 cm above the damaged and salt-loaded area. Scrape out the brittle joint mortar network in a depth of 2 cm. Level with the water-tight patching mortar weber.tec 933.


    4. Chisel a recess of 4 x 4 cm in the groove area (angle wall/floor) so as to obtain a good key for weber.tec 933 with the substrate. If a horizontal damp-proof barrier is existing, chisel a recess of 2 x 2 cm.


    5. Pre-wet the cleaned substrate until dull-moist, except if it is already damp.


    6. Apply weber.tec 933 mixed in brush consistency as bonding layer on the dull-moist substrate.


    7. Apply weber.tec 933 mixed in trowel consistency as patching mortar on the fresh bondcoat into the recess (angle wall/floor) and upwards up to the masonry row with the horizontal bitumen sheet (if any). Afterwards apply the mortar as groove mortar in a radius of 4 - 6 cm with the pre-formed rounded trowel "big size" weber.sys Hohlkehlenschlitten along the angle wall/floor.


    8. The position of the damp-proof barrier depends on the maximal height of the water level and the existence of an exterior water-proofing. In case of non-existing water-proofing and changing water levels the damp-proof barrier must be installed under the basement ceiling and the internal water-proofing must be installed above the damp-proof barrier.


    9. Binding cross walls must be integrated in the internal water-proofing. For this purpose, a vertical  damp-proof barrier with the liquid injection resin weber.tec 940 E or the injection cream weber.tec 946 is carried out. Furthermore, the internal waterproofing with the 2-comp. reactive water-proofing slurry  weber.tec Superflex D 2 is carried out above the damp-proof barrier.


    10. Drill boreholes in the damp masonry in a diameter of approx. 12 mm, at intervals of approx. 10 - 12 cm and at an angle of approx. 35°- 45° for the application of the low-pression hori-zontal damp-proof barrier. The prelimina-ry use of the mortar weber.tec 933 as "blocking mortar" prevents from pressure loss.


    11. Blow dust out of the drilled holes with air. Afterwards place the injection packers into the holes and press the injection resin weber.tec 940 E in low-pressure method through the packers. In case of masonries with hollow space fill the cavities with the cement-based and highly sulphate-resistant mortar weber.tec 942 through special packers prior to injection works.


    12. Drawing of a full-surface internal waterproofing with the subsequent upper horizontal damp-proof barrier in case of non-existing external waterproofing and changing water levels.


    13. The internal waterproofing with weber.tec Superflex D 2 is done in at least 2 layers, using a brush.


    14. After thorough drying of weber.tec Superflex D 2 apply the quick-setting stipple coat weber.san 951 S with full coverage. This bondcoat provides the bonding with the subsequent damp-proof render/plaster.


    15. After drying of the bondcoat apply the damp-proof render/plaster weber.san 954 full-surface in a thickness of 10 - 15 cm and lay the woven glass fiber mesh for damp-proof renders weber.sys 987.


    16. Nach dem Auftrag des Sanierputzes wird dieser mit einer Putzlatte abgezogen.


    17. After initial setting smooth down the damp-proof render/plaster with a sponge board.