Building renovation system
Traditional plasters lack the capacity to effectively accumulate crystallizing salts or withstand stresses during crystallization. Renovating plasters , characterized by high porosity resulting in a low diffusion resistance coefficient for water vapor, facilitate the prolonged accumulation of crystallizing salts in pore spaces. These plasters exhibit high porosity, low diffusion resistance for water vapor, and low capillary conductivity, forming two-, three-, and four-layer system coatings.
The term "renovating plaster" colloquially refers to a specific group of products used in various combinations. The layer arrangement of the system depends on the concentration of building salts, with Cl-, SO -2, and NO- ions being the most common.
Degree of salinity in masonry according to WTA guidelines
The aim of the renovating plaster system is to dry the masonry and create a secure storage for salts that penetrate the plaster along with moisture from the masonry. This is achieved while ensuring a dry surface free of salt efflorescence, thanks to the proper layer arrangement in the renovating plaster system.
PHASE 1
salts crystallize in the air pores of the renovating plaster
PHASE 2
crystals gradually grow and pores are filled
PHASE 3
air pores of the renovating plaster are filled and stresses are taken over by the lightweight fillers
PHASE 4
salt crystals grow and stress increases (the renovating plaster is destroyed)
It is estimated that the salt absorption capacity, and consequently the effectiveness of renovating plaster, lasts between a few years and a decade or longer. The effectiveness of the Ceresit renovating plaster system relies on the proper arrangement of its layers. Therefore, during a building diagnosis, assessing the degree of substrate contamination by building salts is crucial for the correct arrangement of renovating plaster layers. This assessment also affects the system's price per square meter. Inaccurate evaluation may expose the investor to unnecessary costs of installing a system inadequate for prevailing conditions and with a shorter lifespan.
Depending on the degree of salt concentration, a complete renovating plaster system consists of several layers that are applied successively:
- Ceresit CR 60 – renovation rendering coat
Contact layer to improve the adhesion of subsequent layers. The prerequisite is an openwork substrate coverage of <50% and a maximum thickness of 5 mm to maintain the required diffusion.
- Ceresit CR 61 – base renovating plaster
Hydrophilic storage layer used when the salinity of the substrate is high and the substrate is uneven. The minimum required porosity of the base plaster should be 20% for unset plaster and 45% after setting. It also serves as a leveling plaster for very uneven surfaces and defects in the masonry.
- Ceresit CR 62 – renovating plaster
Hydrophobic plaster, usually with a thickness of 2 cm. The minimum required porosity of the renovating plaster should be 25% for unset plaster and 40% after setting. Renovating plaster contains lightweight fillers designed to partially compensate for the stresses arising in the structure of the renovating plaster under the influence of crystallizing salts.
The range of renovating plaster systems also contains CR 64 smoothing plaster. The whole can be finished with paint coatings with very high diffusion and low absorption CR 50 silicone paint or CR 55 sol-silicate paint.
STEP 1
Prepare the substrate.
STEP 2
Check the evenness of the substrate.
STEP 3
Generously moisten the substrate with water.
STEP 4
Apply CR 60. Make sure that the surface coverage is openwork and no more than 50%.
STEP 5
CR 61 base plaster can be applied either manually or mechanically.
STEP 6
Level the surface of the CR 61 plaster with a floating rule.
STEP 7
After the initial setting, texture the base plaster to treat its surface and increase the adhesion of subsequent layers.
STEP 8
Apply the renovating plaster. To prevent cracking, the layer should have a uniform thickness over the entire surface.
STEP 9
Renovating plaster should not be trowelled smooth. You can use a wooden or styrofoam trowel to treat the surface.
STEP 10
To unify the surface at the junction between the renovating plasters and the existing plasters, apply CR 64 smoothing plaster. After the smoothing plaster has set, paint with CR 50 or CR 55.
STEP 11
This is what the wall looks like after the renovating system is applied.
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