Preparation of the base for laying the Thermal Insulation System

With the term “base” is indicated the surface of the wall, on which with suitable technical equipment will be installed a thermal insulation system. Is should be taken into consideration that the base can affect the durability and sustainability of the system. In the most general case the base represents vertical exterior wall. Together with the requirements for its load capacity, stability and air-tightness, in order a thermal insulation system to be applied of the base it:
   - has to be sufficiently straight     
   - should be dry and there must not be water infiltration
   - should be mold and micelles free    
   - should be to the greatest possible extend freed of dust, grease and cleaned from coarse dirt or efflorescence 
   - has a uniform water absorption and no burnings on the surface  
   - has a surface temperature ≥ 5°С (frozen sections are unacceptable)  
   - has a sufficient anchor strength (on dowels with mechanical fastening)

The condition of the base and its suitability for laying a Thermal Insulation System can be checked using the following methods:

Erasing: by bare hand or black (dark) cloth is check whether dust is being emitted and if there is efflorescence on the surface.

Scratching: with hard and sharp object in order to check the strength and load capacity of the base.

Wetting: with brush or spray in order to check the water absorption and moisture in the structure.

Examination of flatness: by the means of a lute for roughness greater than 20 mm.

When laying Thermal Insulation Systems on old buildings is very important the load bearing of the old finish coating to be checked thoroughly (detachment strength at least 0,08 N/mm2). In such building it should be carried out the following verification: on a small area of the old plaster is applied thick layer adhesive for EPS with thickness 3 – 5 mm and in it carefully is plastered-in a reinforces alkali mesh, which in it is lower end stands out at least 40 cm. On the still fresh solution with plastered-in mesh is applied a second layer of adhesive with the same thickness and it is smoothed. After 7 days the mesh is pulled out from the standing out end. If at this a part from the old plaster is removed, then the load bearing of the base is not sufficient for installation of a thermal insulation system through bonding.

Laying and building-in a
reinforcing mesh                                                                                             
Test results: positive.
The base is load bearing.                                                                                                     
Test results: negative. The base is not load bearing.

This method can be used without restrictions on all old plasters, which do not have an additional finish coating (paint) that could affect the adhesion. In order to prevent any problems connected to bonding the insulation boards to the base, all old lime-based pants should be completely removed. All dirty (chalking), but strong paints (for example silicate paints), can be sealed through priming with deep penetrating and strengthening primer.

Depending on the condition of the base, established by the above mentioned checks, the appropriate measures are taken for its preparation for lying of the thermal insulation boards. Is should be made dust-free and cleaned from dirt and deposits, and for this purpose it should be well washed with water under pressure. Efflorescence on the base is sweep and dry brushed. All unsound or swollen parts on it should be removed. The removed parts are filled with suitable building mortar, and the bigger areas are smoothed. At bases, soaked with moisture, the source of moisture is removed and then they are left to dry completely. Areas, covered with fungus or mold are mechanically cleaned and then disinfected with an appropriate cleaning agent. Slightly loose bases should be properly primed with deeply penetrating and strengthening primer.


Related topics

  • What do we have to know about the internal thermal insulation

    What problems causes the internal thermal insulation and what to look for?more...

  • What constitutes a passive house

    What represents the concept of the passive house and criteria should it meet? more...

  • Securing the thermal insulation boards

    How to secure the thermal insualtion boards on the base? more...

  • Doweling of thermal insulation boards

    How does the machanical fastening and anchoringof the thermal insulation boards is done? more...

  • Basic thermal engineering parameters and terms

    Which are the most important variables and terms necessary to determine heat loss and what is their meaning in construction? more...

No comments

Leave a comment