Beyem Bioterm

Adhesive and basecoat, hydraulic lime mortar for natural thermal insulating panels in ETICS.

BEYEM BIOTERM is a polymer-modified and  shrinkage compensated, adhesive and basecoat, natural hydraulic lime (NHL)  mortar for fixing and rendering natural thermal insulating panels (cork,  wood fibre, mineral wool, etc.) in ETICS. Formulated with natural hydraulic lime (NHL), natural pozzolan, selected aggregates and organic  additives. Natural composition. Free of Portland cement. Indoor environment quality. Classifed as  A+ class according to Décret nº. 2011-321 (France). Free of radionuclides.

  • Suitable for spray render and pump machines or manual applications.
  • High water vapour permeability. Allows the wall to breathe.
  • High deformability.
  • Excellent impact resistance.
  • High  bond strength on ICB, WF and MW panels.
  • Compatible with old masonry brickworks/walls.
  • Great plasticity. Excellent adhesion.
  • Rainwater- proof. Weather resistant.
  • Free of chlorides.
  • Suitable for internal or external walls.
  • New construction and building rehabilitation.
  • Natural bacteriostatic and natural fungistatic.
  • Very low VOCs  emissions.
  • Radiation-free certificate.
  • Mineral product.

Bonding and levelling of natural thermal insulation boards (expanded or agglomerated cork –ICB-, wood fibre  -WF- and mineral wood -MW -) in ETICS. Bedding coat for meshcloth insulation systems.

Specially suitable for rendering walls in rehabilitation works (old buildings) and for the treatment of cracks in facades with hydraulic lime  based system. 

BEYEM BIOTERM is suitable for:

    Bonding of natural thermal insulation panels:

  • New construction and rehabilitation brickwork. Ceramic bricks. Traditional plastering /rendering mortars. Stonework.
  • Bricks, cement based substrates and concrete blocks.

    Levelling thermal insulation panels:

  • Expanded or agglomerated cork board, wood fibre and  mineral wood  panels.

     Anti-cracking system:

In cases not described, contact Technical Support.

Substrates must be clean, compact and free of substances that reduce adhesion such as dust, oil, grease and with no loose material. Substrates must submit an adequate porosity and surface roughness. Uneven areas must be corrected. Dampen substrates with water to cool down and wait until the thin layer of water disappears. This operation is essential to avoid rapid drying and depends on the degree of porosity and surface absorption. Do not apply on gypsum-based plasters, paint, metal surfaces, plastic, surface waterproofing products or materials with low mechanical properties.

Mix manually of mechanically BEYEM BIOTERM with 6,0-7,0 l per bag of clean water until a homogeneous, creamy and lump-free paste  is obtained. Let the mix stand for 5 minutes before application.

As adhesive: Apply BEYEM BIOTERM directly on the edges of the panel in perimeter strips (4-8 cm width and 2-4 cm thickness)  and several 8-10 cm Ø spots in the centre of the boards, depending of the size of the panel. The minimum bonded surface area must  be at least  80%. Alternatively, use the notched trowel method for planimetrically correct substrates, spreading the product over the whole surface of the board.

As basecoat: 24-72h  after installing the panels, fix corners profiles and reinforcement mesh in gaps. Insert fasteners and regularize any existing irregularities with the same BEYEM BIOTERM mortar. Treat conveniently the singular points. Spread a layer of mortar directly onto the insulation panel and then regularise the level with a notched trowel.

Unfold the reinforcement mesh of 160 gr/ m2 from top to  bottom and press the mortar grooves until they are completely embedded in them. Joints of reinforcement mesh must be overlapped by at least 10 cm. This layer should be at least 2 mm thick and the squares of the embedded mesh should be visible through the surface. Once this layer has hardened, a second layer of BEYEM BIOTERM is applied (1-3 mm) to finish the covered surface.  The finishing coat can be applied at least 48-72 hours after last application of base coat.

  • The boards should never overlay  the expansion joints of the building.
  • Do not apply on plastic, metal or wood.
  • Do not apply below 5ºC or above 30ºC.
  • Do not apply when there is  risk of frost, rain, strong wind or direct sunlight.
  • Do not apply to areas where there is a possibility of stagnant water.
  • It is mandatory to use ancillary elements: base profiles, corner profiles, etc.
  • The minimum number of fasteners per square metres is 6 for ICB/WF/MW and 8 fasteners for building higher than 25m.
  • Reinforce the critical points of facade  before first layer of basecoat using reinforcement mesh of 160 gr/ m2 and fixing it with BEYEM BIOTERM.
  • Do not finish the insulation system with conventional renders.
  • Contact areas with  base/top profiles will be sealed with elastic joint sealant.
  • Anti-cracking system in combination with BEYEM NEOCAL MURO and natural mesh. Do not use as a plaster directly on the wall.
  • Lime mortars have a slower setting, so the hardening time increases.

Product identity. Properties of mixture and application data





Bulk density

≈ 1100 Kg/m3

Density of the mix

≈ 1530 Kg/m3


0-600 µm

Mixing water,%

± 26%

Minimum thickness application as adhesive

≈ 2 cm

Maximum thickness application as adhesive

≈ 5 cm

Minimum thickness application as basecoat

≈ 3 mm

Maximum thickness application as basecoat

≈ 5 mm


≈ 1,25-1,750 Kg/m2  per mm  of thickness

Tariff code


Final performances





≥ 0,30 MPa

Bond strength onto insulation board

≥ internal cohesion of the board or ≥ 0,15 MPa

Compressive strength

≥ 6,0 MPa

Flexural strength 

≥ 2,0 MPa

Thermal conductivity

0,53 W/m·K

Reaction to fire

Euroclass  F

Total VOCs (28 days)

< 500 µg/m3

Radioactivity index (U, Ra, Pb, Th, others)

I = 0,197

BEYEM BIOTERM is packed 25 kg plastic lined paper bags.

Storage:  when stored unopened in a cool dry place, shelf life is 12 months from date of manufacture.

Tools can be cleaned easily with water  before the product hardens. Hardened product can be remove only mechanically.

Bonding and leveling of ICB, WF and MW panels for External Thermal Insulation Composite System (ETICS), must be carried out with polymer-modified, shrinkage compensated adhesive and basecoat, natural  hydraulic lime mortar compliant with  EN 998-1 –Class GP CSIV Wc2, such as Beyem Bioterm manufactured by Rodacal Beyem company. Coverage will be ≈ 1,25-1,75 kg/m2 per mm of  thickness. The substrate must be clean, sound, compact and dimensionally stable. Expansion joints must be respected.

For further and complete information about the safe use of our product please refer to our latest version of the Safety Data Sheet, which is available upon request.

Disposal of the product and packaging must be in accordance with current legislation. This is  responsibility of the final product user.


Technical sheet

Component Safety Data Sheet

Declaration of benefits

Factory Production Control Certificate

Certificado Sistema Gestión de Calidad ISO 9001

Certificado Sistema Gestión de la I+D+i UNE 166002

Declaración Compuestos Orgánicos Volátiles

Certificado Libre de Radiación


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