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StoTherm Classic M

StoTherm Classic M

Third party certifications:
  • BBA Agrément Certificate

    BBA Agrément Certificate

    Certificate type

  • QA Certificate

    QA Certificate

    Certificate type

Sto Ltd

An external wall insulation system with EPS board and cement-free components, providing unrivalled impact resistance. StoTherm Classic M is mechanically fixed to the wall.

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+44 (0)141 892 8000 www.sto.co.uk

The StoTherm Classic M System comprises an impact resistant, flexible render finish applied over fire retardant treated expanded polystyrene insulation boards. The insulation is fixed by means of either Sto Rotofix Plus or Sto Rotofix mini helix spiral fixings.

The system may be fixed to either bare concrete or masonry, previously rendered / painted concrete or masonry, or onto a light steel framed or timber framed construction with suitable sheathing board.

Through coloured render finishes are low maintenance, weather resistant and vapour permeable, with a reaction to fire classification of A2-s1, d0. The system achieves a reaction to fire classification of B-s2, d0 and may be used on buildings with a storey level up to 18 m above ground level (11 m in Scotland).

For insulation and finishes to below DPC zones consult manufacturer.

Quick Set (QS) versions of materials offer frost resistance and wash-off protection at temperatures from +1°C and 95% relative humidity, reducing potential construction delays due to cold weather - consult manufacturer for recommendations.

Fixing pattern will be dependent on insulation thickness, substrate type and wind load conditions. Consult manufacturer for further information.

Specify framing system separately.

General information


High performance decorative and protective finishes


Seamless render with high impact and crack resistance using cement free technology


Company warranty

Uniclass 2015

Ss_25_45_72_02 Adhesive-fixed external wall insulation systemsPrimary


M21/20 External wall insulation system

M21/210 External wall insulation system

Specification data - Adhesive-fixed external wall insulation systems

Product Reference

StoTherm Classic M Rotofix Mini System

StoTherm Classic M Rotofix Plus System

Base board



Specify other as recommended by manufacturer.


For cement particle boards and calcium cement boards, minimum 12 mm thick. For Plywood or OSB, minimum 18 mm thick. Consult manufacturer for details.




Sto-EPS board K90/FRA , square edged

Sto-EPS board K90/FRA, tongue and groove edged

Sto-EPS grey Lambdatherm board K90/FRA, square edged

Sto-EPS grey Lambdatherm board K90/FRA, tongue and groove edged


See Options and consult manufacturer for details and recommendations.

Method of fixing

Sto Rotofix Mini

With squared edged boards.

Sto Rotofix Plus

With tongue and groove edged boards.

Beads/ Trims

Sto-Aluminium Flexicurve starter track

To radius.

Sto-Aluminium starter track profile

Sto-Armour Angle

To internal angles.

Sto-Clip-on 3 mm Bead

Sto-Mesh Angle Flexibead Ideal

To variable external angles.

Sto-Plinth PVC Profile PH

For passive house construction.

Sto-PVC Mesh Angle Bead

To 90º external angles.

StoSeal Bead Perfekt

Head and reveal profile with telescopic mechanism and integrated glass fibre mesh.

StoSeal Bead Supra

Head and reveal profile with integrated sealing tape and glass fibre mesh.

StoSeal Joint Sealing Tape Lento

Pre-compressed joint sealing tape for use at interfaces.

Sto-Starter Track Connectors

Sto-Starter Track PH-P

For passive house construction.

Sto-Stop Bead Standard

Head and reveal profile with integrated glass fibre mesh.



Reinforcing base coat

StoArmat Classic Plus cement free reinforcing plaster

Reinforcing mesh

Sto-Armour Mesh

Robust reinforcing mesh applied prior to standard mesh for increased impact resistance.

Sto Glass Fibre Mesh applied into reinforcing coat

Standard reinforcement.

Finish coat

Stolit Effect

Acrylic resin bound render finish used to achieve special render effects.

Stolit K

Acrylic resin bound render with stippled texture.

Stolit Milano

Acrylic resin bound render finish with fine grain used either alone or with Stolit K/ Stolit Effect to achieve special render effects.

Stolit MP

Acrylic resin bound render with rustic texture.

Stolit R

Acrylic resin bound render with rilled texture.

StoLotusan K

Super-hydrophobic render finish with stippled texture and Lotus Effect.

StoLotusan MP

Super-hydrophobic render finish with rustic texture and Lotus Effect.

StoSilco K

Silicone resin bound hydrophobic render with stippled texture.

StoSilco MP

Silicone resin bound hydrophobic render with rustic texture.

StoSilco R

Silicone resin bound hydrophobic render with rilled texture.

StoSuperlit K

Acrylic bound render finish with exposed natural stone aggregate.

Colour/ Aggregate

See 'Options' and insert requirement. Refer to StoColor system and Sto Architectural colour range for colours. Consult manufacturer for details and samples.

Additional requirements


As shown on drawing ___

Product Options

Board substrate:

Type: Various types of cement particle, calcium cement, OSB or plywood boards. Gypsum based sheathing boards are not generally suitable for mechanically fixed systems.


- Thickness:

  • Square edged from 60–120 mm rising in 10 mm increments.
  • Tongue and Groove edged from 80–300 mm rising in 10 mm increments.

Consult manufacturer for details and recommendations.

- Minimum compressive strength:

90 kN/m².


Insert Sto product references or refer to detail drawings - consult manufacturer for details and recommendations.

Reinforcing mesh:

Sto-Armour mesh – additional reinforcing mesh used in conjunction with standard mesh to provide increased impact resistance.

Mesh to be applied into base coat render ensuring the reinforcing mesh is fully embedded.

Impact loading (ETAG 004):

  • Single layer - Category II.
  • Single layer Armour mesh + single layer standard mesh - Category I.

Consult manufacturer for details and recommendations.


- Finish coat:

  • Render finishes are available in a range of up to 800 colours from the StoColor System and a further 300 colours from the Sto Architectural colour range.
  • X-black near-infrared reflecting formulations available with some finishes where dark or intense colours are required. Consult manufacturer for information / details.
  • Other finishes: Sto Resin Brick Slips, Sto-EcoShapes, StoDeco Profiles, StoDeco Rustications, plus other options may be used as an alternative to or in conjunction with render finishes. Consult manufacturer for information/ details.


  • Stolit: 1.5, 2, 3 and 6 mm grain size.
  • StoSilco and StoLotusan: 1.5, 2 and 3 mm grain size.
  • StoSuperlit: 2 mm grain size.

Additional requirements:

  • Specify movement joint trims etc. or refer to detail drawings.
  • Specify areas for additional reinforcement mesh to be located e.g. at locations prone to impact.
  • Specify location of all horizontal (and vertical where required) fire barriers or refer to construction drawings.
  • Provide details of brick coursing, bond and features to quoins, door/ window heads and raised feature bands or margins around doors/ windows etc., or refer to drawings.

Digital objects
PlatformCompatibleVersionCertified to
- 5 2.1
- 5 2.1
Download now from NBS National BIM Library
Third party certifications
  • 95/3132 : Product sheet 1
  • European Technical Approval : Consult manufacturer for details
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