Seal the exterior plaster and make the base area watertight


The exterior plaster on a building is subject to special stress in the lower area near the floor. Moisture from the ground, through rainwater and possibly from the masonry increase the durability. With a sealing of the so-called base plaster damage can be avoided. The building physics balance is important.

Including moisture always involves risks

Near the ground, the biggest problems for the moisture balance of the building often arise. The facade plaster touches the perimeter insulation here. At this critical point, the question arises as to whether the actually vapor-permeable plaster must be sealed in a manner that is impervious to air and water. Moisture and moisture must be kept away from the masonry and at the same time an increase in the masonry must be considered.

A classic example of the difficulty is a barrier plaster in the basement. It seals the basement wall from the inside and the existing moisture in the masonry can no longer evaporate on the inner walls. If the exterior plaster of the house in the base area is also sealed air- and waterproof, the moisture seeks new ways.

Construction and transition of plaster surfaces

In addition to the moisture balance of the building, the continuous insulation without thermal bridging must be taken into account. In most cases, a base plaster is attached, which supports a heat-bonding system. The construction and transition is done in several steps:

  • Wall plaster strikes the height of the base plaster about fifty centimeters above the ground
  • The base plaster connects the wall plaster with the perimeter insulation
  • The perimeter insulation made of bitumen or other impervious insulation seals the masonry
  • At the transition of the plasters from wall to base a interlocking entanglement must occur for sealing

Sanierputze as a rescue

In case of unclear building physics and thermal situations and conditions, the application of a restoration plaster can also be a solution outdoors. In the form of a sacrificial plaster, it absorbs the moisture and relieves the masonry. A renovation plaster, however, must be renewed every five years.

In order to prevent rising damp in the masonry with sealing on both sides by sealing with exterior and interior plaster, barrier barriers such as injections or water barriers in masonry are required.

Tips & Tricks

In the construction trade, you will receive special colors with which you can paint your base plaster. This saves you the combination of two different plasters, as you can simply pull through the wall plaster of the facade as far as perimeter insulation.

Artikelbild: ronstik / Shutterstock


Video Board: Exterior Waterproofing, How To Seal Your Foundation, DIY