AISTERM system with ceramic and acrylic finish in energy-efficient homes

System description

Nowadays, energy saving has been strongly incorporated into the world of architecture, as a trend focused on the design of passive systems, i.e. architectural designs that aim to make better use of our environment and building materials.

The result is what is known as passive houses, also designed with a perspective based on the health and quality of life of the tenants.

The project developed by the company SG Arquitectura has managed to apply this new philosophy practically in its entirety in the two houses it has built in the Biscayan municipality of Meñaka, since the enclosures (façades, floors, roofs and partitions) meet the requirements thanks to their optimum level of insulation and excellent treatment of thermal bridges, without the need for double flujo ventilation with heat recovery.

This article explains in detail how this façade insulation has been carried out with the Molins External Thermal Insulation System, SISTEMA AISTERM.

Description

According to the descriptive and constructive report of the project, it is a single-family house and another two-family house that adapt to the topography of the plot, and are developed in a semi-basement, ground floor and first floor. The façade area of the one-family house is 194 m2. The façade area of the two-family house is 306 m2.

The construction typology is traditional, but built with state-of-the-art materials, based on a reinforced concrete structure, brick partitions, façade with SATE system finished with coloured acrylic mortar and natural stone, PVC exterior carpentry and sloping roof finished with concrete tiles.

The external façade enclosures ensure resistance to the action of the wind, acoustic attenuation higher than that required by the CTE-DB HR, watertightness to rain or snow and a thermal transmittance lower than that required by the CTE -DB HE for the C1 zone in which the building is located.

In order to eliminate the effect of thermal bridges in pillars, slab fronts, the contour of openings, etc., the necessary construction measures have been taken. The most effective is to provide thermal insulation on the outside. Thus, above ground level, the composition of the façade is as follows:

Solution for the buried façade:

Challenges and constraints

“The cladding project for the façades of the dwelling envisages a mixed finish based on acrylic mortar and natural stone; therefore, waterproofing must be a basic technical characteristic of the filling material for the tile-to-tile joint and of the acrylic mortar.
“For the fixing of the insulation boards, a mortar is required to bond the SATE to the base material and to transfer thermal loads and stresses (expansion/contraction), as well as mechanical fixings that work with the former to counteract horizontal stresses and loads (wind suction/depression).
“The reinforcement layer made on the insulation panels must constitute a stable and resistant support on which to install the ceramic cladding and the acrylic mortar.
“The SATE (Exterior Thermal Insulation System) must be an indispensable element in the construction of this house in order to obtain global energy efficiency indicators (annual CO2 emissions and annual consumption of non-renewable primary energy), as well as partial energy demand indicators for heating and cooling, which will allow an A rating to be achieved.

Molins Solution

“The Exterior Thermal Insulation System applied to the façades is the AISTERM SYSTEM (ETE 09/0005) for the façades finished with acrylic mortar, and the AISTERM CERAM SYSTEM (DIT 609/15) for the natural stone finish.
“The insulation panels used are PROPAM® AISTERM EPS GRAFITO, with a thermal conductivity of 0.032 W/mK.
“The adhesive fixing of the insulation panels to the substrate was carried out with PROPAM® AISTERM mortar. For mechanical fixing, the PROPAM® AISTERM TACO ABCDE dowel was used, to be installed by screwing.
“The reinforcement layer was made by applying PROPAM® AISTERM mortar on the insulation panels, with REVAT® 160 fibreglass mesh (weight 160 g/m2) centred on the thickness.
“The highly deformable adhesive used for laying the natural stone is VAT® SUPERFLEX (C2TES2 according to UNE EN 12004).
” BORADA® PLUS (CG2WA according to UNE EN 13888) was used as grout.
“The low-density thermal mortar PROPAM® TERM 50 (T1 CS1 W1 according to UNE EN 998-1, thermal conductivity 0.05W/mK) has made it possible to resolve numerous critical points where the use of the insulating board was complicated.
“The acrylic mortar-based coating was carried out with the REVAT® PLAS SLX system on the REVAT® FILM underlay.

Execution

“The Arliblock® blocks used to build the walls are lightweight concrete blocks, which can be used as an efficient system for the construction of load-bearing walls in low-rise buildings, two storeys at the most, as in this case. For the installation of the AISTERM SYSTEM on this type of construction element, it was decided to previously reinforce its surface with the application of a type M 7.5 mortar and to carry out traction tests on the PROPAM® AISTERM TACO ABCDE mechanical anchors that would later be used to fix the insulation panels.

“Once it was verified that the tensile strength is greater than 1.5 N/mm2, the PROPAM® AISTERM EPS GRAFITO panels were installed from bottom to top in two consecutive layers, the first one, 10 cm thick, made it possible to eliminate the wall recesses with respect to the edges of the slab and pillars. The second, of the same thickness, was applied on top of the first so that the total thickness of both layers corresponds to the 20 cm thickness defined in the project.

“The first layer of panels has been laid by applying PROPAM® AISTERM mortar using the perimeter bead and three central sticks.

“The surface evenness of this first layer has allowed the second layer to be laid by continuous gluing (with a notched trowel gluing the surface of the substrate and the back of the panel).

” 5. The mechanical fixings have been installed in accordance with DIT 609/15, but replacing the PROPAM® AISTERM TACO ABC dowels, with a fibreglass-reinforced polyamide core and percussion anchoring, with PROPAM® AISTERM TACO ABCDE dowels made of galvanised steel and screwed anchoring. This has led to significant improvements:
a” Decreased risk of damage to the Arliblock® substrate as a result of the impact or percussion of the anchor, as the screwing procedure produces a less aggressive indroduction into the substrate.
b” Effective anchorage depth is lower than that required by the polyamide core, and consequently, less damage to the substrate.
c” Greater durability of the metal core compared to the polyamide core.
d” For all the above reasons, better fixation of the insulation to the Arliblock® substrate.
As it is embedded, it has achieved a greater elimination of thermal bridges, and reduces the possibility of aesthetic defects appearing in the finished cladding.

“Once the insulation layer had been applied, to avoid the appearance of cracks, the corners of doors and windows were reinforced with REVAT® 160 mesh. To do this, 20×40 cm pieces of this mesh were placed directly on the panels, diagonally at 90° to the bisectors that form the corners of the doors and windows (A). Then, inside the openings, the mesh was applied so that it protruded 20 cm on each side of the angle and 10 cm over the exterior façade (B). Finally, PROPAM® AISTERM corner profiles were installed (C). The installation method is illustrated in the following diagram, in which the PROPAM® AISTERM mortar is not shown for the sake of comprehensibility.

“In those façade areas where the finish is natural stone, in accordance with DIT 609/15, an additional PROPAM® AISTERM TACO ABCDE block was installed for each square metre of insulation. The natural stone cladding was then laid with a notched trowel using the double gluing process with VAT® SUPERFLEX (C2TES2) adhesive with high adhesive capacity and maximum deformability. The grouting was carried out with BORADA® PLUS (CG2 WA), highly resistant to abrasion and waterproof, with anti-mould and fungicide effect.

“Facades finished with REVAT® PLAS SLX acrylic mortar have been previously treated with REVAT FILM® primer, thus ensuring greater adhesion of the coating to the substrate. REVAT® PLAS SLX is an anti-mould coating with a high water-repellent (drop effect) and photocatalytic properties, technical characteristics that provide a number of additional advantages:
1- by completely repelling water, superior protection of the facades is achieved and less maintenance is required, as they remain clean for much longer due to the self-washing effect of the rainwater itself,
2- delay in the effects of UV on the colour, and consequently greater aesthetic durability.

Reference documentation

DIT 609/15, ETE 09/0005, Technical Specifications for the PROPAM® AISTERM CERAM SYSTEM.