External Wall Insulation

The purpose designed, Savotherm laminated insulation board forms the heart of an external wall insulation system that is simple to install. The boards, trims and sections are easy to cut and fasten and the application of render only requires the skill of a competent plasterer. Originally designed for the external insulation of solid masonry walls Savotherm insulation boards can span up to 1000mm and so may also be applied to timber or steel frame walls. Traditional lime renders and other render products may be applied on Savotherm boards but approval should be sought prior to application.

Board Sizes

The Savotherm insulation board consists of non combustible rockwool core sandwiched
between two layers of wood cement composite. It is available in the following sizes:

  • 2000 × 600 × 35 mm
  • 2000 × 600 × 50 mm
  • 2000 × 600 × 75 mm
  • 2000 × 600 × 100 mm
  • 2000 × 600 × 125 mm
  • 2000 × 600 × 150 mm

Savotherm External Wall Insulation System


  1. Savotherm
  2. Dowel fixings
  3. Window reveal insulation
  4. Render base coat
  5. Render reinforcement scrim
  6. Reinforcement scrim bandage
  7. Render top coat
  8. Base/eave drip trim
  9. Corner bead trim

External wall insulation

  • Converts external walls from heat radiators to heat stores
  • Reduces heating costs
  • Provides stable and constant interior temperatures
  • Eliminates water penetration
  • Eliminates condensation on interior walls
  • Improves building appearance
  • Extends the life of buildings

Installation Guide

Base Profile

Base / eave drip sections are aligned horizontally and fixed with suitably plated screws and plugs to the wall. The minimum distance from the edge of the base profile to the ground surface should not be less than 200mm and the base profile should not be positioned below any damp course. The base profile section seals off the bottom edges of the Savothem board and also forms a render drip edge.

Savotherm Insulation Boards

The first course of Savotherm boards is placed on the base profile and each board is initially fixed in the centre with a dowel. The boards are placed horizontally, in broken bond, butted tightly together and fixed with dowels at the board butt joints. Board end joints are alternated at building corners. Any narrow cut board pieces should additionally be fixed with C84 Adhesive. Prior to installation Savotherm boards should be stored dry and flat. Boards are cut with hand or circular saw. Small pieces are best cut with the board laid flat and both pieces installed immediately to minimise wastage.


Dowels are placed at board joints at maximum 600mm centres. Extra dowels are used at corners, along the base profile and around openings (see diagrams). The number and length of dowels will depend upon the type of masonry, building height, wind loadings and render weight. It is the responsibility of the installer to ensure the correct number and length of dowels are used and, if necessary, to carry out drilling and dowel pull-out tests.

Dowels Required  
Minimum 6 no./ m² Savotherm Wall Anchor
Click for larger image
Average 8 no./ m²

Corner Bead

Corner beads ensure the render is true and are cemented to the Savotherm board surface with C84 Adhesive at external corners of walls, doors and window reveals and aligned and positioned to suit the render thickness. The glass fibre render reinforcement mesh is taken up tight to the corner trim.

Expansion Joint/Movement Joint Bead

Large uninterrupted areas of render should be divided at intervals of approximately 5 metres with movement/expansion joint beads and these also should be installed at connections to existing structures and structural expansion joints. Where expansion/movement joint beads are fitted the Savotherm boards should be cut through to the substructure. Expansion/movement joint beads are cemented to the Savotherm board surface using C84 Adhesive.


Reveal insulation pieces are cut from Savotherm or Savolit board and stuck around door and window reveals with C84 Adhesive and additionally fixed with dowels at 500mm centres. Reveal pieces prevent heat transfer and so with old buildings it is important to remove any existing render to gain space for the thermal insulation. At the window jamb the render must be cut with the trowel edge and the joint filled with suitable flexible filler.

Render Reinforcement Mesh

It is recommended that render reinforcement mesh is incorporated within renders applied to Savotherm and Savolit boards to absorb stresses. The mesh edges must be overlapped at least 100mm (coverage approx. 1.2m² for each square metre of wall surface). In addition, strips of mesh 600 x 200mm, should be placed diagonally as reinforcement to absorb stresses at corners of doors and windows.

Savotherm Advantages

  • Resistant to impact and compression damage
  • Tough, rigid, easily cut and fix insulation boards
  • Secure mechanical fastening
  • Can install over existing rendered walls
  • Insulation boards can span over irregularities
  • "Breathing" system allowing moisture diffusion
  • Sound insulating and fire resistant
  • Good render bonding board surface
  • Well-proven, two-coat, through-colour render system
  • User friendly system available direct for building contractors
  • Full technical support and site instruction available

Technical Data

Property Units Data
Thickness mm 35
Length mm 2000
Width mm 600
Weight kg/m² 10.8 12.3 15.4 18.7 22.1 25.5
Declared thermal conductivity  λD W/mK WW: 0.071 - MW: 0.039
Declared thermal resistance  RD m²K/W 0.75 1.15 1.80 2.45 3.05 3.70
Water vapour transmission  µ   WW 5 - MW 1
Reaction to fire   Euroclass B-s1, d0
Compressive strength  σm kPa ≥ 50
Tensile strength perpendicular
to faces  σmt
kPa ≥ 15 ≥ 20