Cementos Molins

Waterproofing foundations on new buildings

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One of the main functions of cements and embedded concrete walls is to prevent humidity from the ground reaching the building.Therefore it is necessary to form a waterproof barrier between the ground and this type of construction elements.

When this barrier does not exist, the moisture coming from the ground penetrates the foundation and rises through it towards the upper walls by capillarity.

For this reason there are spots of humidity in the basements of buildings, which creates unhealthy  and harmful to health environments.

In addition, the constant presence of moisture in the coatings causes degradation.

To achieve impermeability in foundations and concrete walls, PROPAM® IMPE must be used, ie a hydraulic coating mortar capable of withstanding positive and negative hydrostatic pressure. Use PROPAM® IMPE FLEX (single-component mortar) or FLEXITEC (two-component mortar) waterproofing mortars with great adhesion and flexibility for the waterproofing of structures subject to small movements or vibrations.

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The substrate must be stable (wait a minimum of 28 days from the execution of the concrete element), and be clean of dust, paint, laitance, curing agents, etc.


Knead PROPAM® IMPEPROPAM® IMPE FLEX or FLEXITEC with a slow electric mixer (500 rpm) and 30% clean water until a lump free grout is obtained.

Prior to application the substrate should be slightly moistened with water.

When the surface is quite irregular, it is advisable to apply a first layer with a mortar consistency with the aid of a trowel (approximately 20% water).

Apply a first layer on the surface, previously moistened, with a brush or roller in only one direction. Do not overextend the material. Leave a good layer so that the waterproofing is correct.

After 24 hours, apply a second layer crosswise to the first one.

The final finish of PROPAM® IMPE, PROPAM® IMPE FLEX or FLEXITEC can be done by flattening with a trowel or trowelling.


  • Repair the degraded concrete substrates with the appropriate repair mortar (see range available in the PROPAMSA catalogue), prior to the application of the waterproofing mortar (PROPAM® IMPE, PROPAM® IMPE FLEX, FLEXITEC).
  • Use PROPAM® SEC to refurbish exterior walls affected by moisture and efflorescence.
  • Do not use PROPAM® SEC for foundation waterproofing.



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