Internal Wall Insulation - Schneider Wood-Fibre Insulation System

Preparation

• The masonry wall should be prepared be removing any loose friable materials and dubbing out and deep voids and joints as required.
• If the wall has an existing lime plaster that is well adhered this can be retained and the levelling coat below excluded. If a non-breathable render (cementitious) is in place then we would recommend removal of this where possible to maintain the breathability and help the wall manage moisture.
• If removal is not an option then this can be retained and the insulation board can be adhered directly to the existing render however this will affect how the wall manages moisture. 

Lime plaster levelling coat

• The insulation boards must be adhered to a flat surface wihtout voids, to achieve this most masonry walls will require a levelling coat of lime plaster.
• The thickness of the plaster coat will depend on the surface of the wall, very uneven walls may require multiple layers.
• This plaster can be any basecoat plaster suitable for the substrate but is usually a hydraulic plaster for efficiency, options include St. Astier Ecomortar C, Secil Reabilita Cal RB or site mixed hydraulic lime plaster.  

Adhesive

• The insulation boards are adhered to the surface of the wall using the SecilTek Isovit Lime Adhesive, this is applied with a notched trowel to the board or the wall (similar to tiling). 
  Insulation Board

Insulation Board

• The insulation layer is a Schneider Multitherm140 wood fibre board in 40mm to 60mm thicknesses. This thickness is limited due to interstitial condensation risk caused when insulating internally, for more information see detail here

Masonry Fixings

• The insulation boards can be further secured using insulated masonry fixings if required, Fixings should be at least 40-50mm longer than the insulation board used and are used at 8 fixings per square meter. Internally fixings are optional however if the background is non-breathable such as painted or cementitious render then they should be used.  

Lime plaster

• The insulation board can be plastered with Ty Mawr Lime hemp plaster or with the SecilTek Isovit Lime and Reabilita Cal AC system depending on the desired internal finish. We have a range of options please see information on plastering over insulation boards here