The technological process of installation of any thermal insulation system is very important. Omission and neglect of some main processes when laying a thermal insulation board could cause not only a decrease of their effectiveness, but also a violation of their integrity.
By following some essential rules can save you a lot of trouble and money.
1. Appropriate Substrate
It is extremely important to take into consideration the substrate onto which you will install the thermal insulation boards. All surfaces must be free of dirt, of grease, of loose parts on the substrate, as well as of any other contaminants that could subsequently influence on the bonding properties of the adhesive mixture. Mistakes that are often made are not levelling the substrate or omitting to apply a suitable primer to strengthen it.
2. Adhesive Application
In order to avoid sliding of the thermal insulation boards, excellent bonding of the adhesive mixture to substrate must be ensured. This depends both on the correct preparation of the adhesive mixture, the amount of adhesive to be applied onto the material, and the method of its application. The application of the adhesive mixture can be done in two ways depending on the type of substrate and its unevenness:
Method I: When the substrate is uneven, an adhesive layer has to be applied along the border line of the insulation board with a width of at least 3-4 cm and a thickness which can ensure that unevenness may fully be overcome. Substrate unevenness that exceeds 2 cm should not be compensated. In the inner part, 3-6 spots of adhesive are applied in the middle line of the insulating material. The amount of adhesive mixture should cover no less than 40% of the total surface of the insulation board.
Method II: When the substrate is even, spread the adhesive mixture over the entire surface of the insulation board by using a notched trowel (10 to 12mm Cut)
Avoid applying too much adhesive onto the insulation board as the excessive layer thickness may cause too much shrinkage after curing. As a result, the size of the bonding area will change and cracking and breaking will occur in the integrity of the main coating at a later stage. It is not uncommon to observe a complete impairment of the TIS (Thermal Insulation System).
3. Arrangement of the thermal insulation boards
A common mistake to avoid is the alignment of vertical joints. Insulation boards must have the joints between the boards staggered in all directions. Also, vertical joints must not occur at the corners of window and door openings or over window heads. Such omission will consequently cause impairment and even destruction of the entire TIS (Thermal Insulation System). In case that laying of single thermal insulation sheets is not performed in an appropriate manner (with large joints between panels and seeping adhesive solution instead of polyurethane foam), a thermal bridge will be formed and a significant part of the heat in the insulated room will be lost due to the thermal conductivity. Another significant concern, as a result of improper joints grouting, is the formation of hot and cold areas. Consequently, when warm, humid air contacts a cold surface, condensation may form and mould will appear on surfaces inside.
In case that the doweling operations of the thermal insulation boards are not technologically performed in an appropriate manner, this can cause impairment of certain sections or the facade as a whole. It is also of essential importance to select the right dowels, depending on the type of substrate and the insulation material, as well as to comply with the doweling scheme and the number and spacing of dowels in each area. It is recommended using at least 6 dowels per square meter and it is mandatory to comply with the technological schemes depending on the loading. Dowels reinforcement should be provided at the edges of the buildings. This will take place at least 24 hours after bonding of insulation boards, so that the adhesive material will be sufficiently cured and sinking of the thermal insulation material will be avoided. Dowels must be inserted only where the adhesive is placed. When driving the dowel head into the insulating material it must slightly sink into the insulating material in order to avoid unevenness. When the dowels are too small, they cannot be inserted into the facade very well and thus the dowel action of reinforcement will be reduced. When the dowels are too big, on the other hand, they bend and protrude above the surface of the thermal insulation board, thus causing defects. Overall grinding of bonded thermal insulation boards will ensure a good surface flatness.
5. Placement of fiberglass reinforcement mesh
Using quality alkali-resistant fiberglass reinforcement mesh on the insulated surfaces is an essential factor, which will guarantee resistance to cracking when inserted appropriately in the putty layer. The omission of diagonal reinforcement along the window and door openings will cause the formation of cracks, which are most often appearing in the corners of the windows as a result of the accumulation of tension. Reinforcement is required at the diagonal area and therefore a mesh strip should be inserted in the substrate layer perpendicular to the area of potential cracks. Placing must be performed before laying the fiberglass mesh on the facade.
6. Applying a putty layer
Selecting quality putty materials, depending on the insulation material, is a guarantee of achieving a good and resistant putty film. Putties must contain fibres in order to provide cracking resistance of surface layers. At least two layers of putty should be applied, with the fiberglass mesh inserted in the first layer. If surface cracking occurs, this will be a precondition for moisture to enter and disrupt the finish coating.
7. Substrate priming
If you proceed directly to the application of a finishing layer and omit the application of a suitable primer, you may end up with a poor quality of the finishing coating. The plaster falling off will be due to its poor adhesion to the substrate. Various defects may appear under the influence of moisture, such as stains, unevenness, cracks etc.. Tinting the primer in the colour of the plaster is recommended. Otherwise, small gaps in the texturing of plaster can expose the substrate and the difference in the substrate colour could be noticed.
8. Plaster Application
When preparing the plaster, dilutions play a crucial role in quantitative estimations. Depending on the type of plaster, there are different requirements for the application tools to be used. Chrome-nickel plated tools should be used to apply any types of decorative mineral plasters. Plastic Texturing trowels should be used for finishing top coat structuring. When working on larger areas, application should be done by several people without interrupting the finishing top coat from edge to edge or inside corner. It is best for large-area to use plasters from the same batch in order to avoid colour discrepancies.
9. Work in adverse weather conditions
Installation works must be carried out only in recommended weather conditions. It is not allowed to work during rain, fog, direct sunlight or temperatures below +5°C and higher than +25°C. Adhesive mixture dries very quickly when heated too much and bonding with the board will be impaired, which, in turn, will create a prerequisite for falling off. When the temperature is too low, freezing can cause the destruction of the putty and finish layer and facade lightening and staining also frequently occurs.