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Knauf InsulationKnauf Insulation.

Knauf Insulation is the UK 's leading manufacturer of insulation solutions and the sole producer of all three types of insulation: glass, rock and XPS in the UK under the brand names; Crown®, Rocksilk® and Polyfoam®. The company employs around 500 people producing a range of insulation products at its four manufacturing plants in St Helens, Queensferry, Cwmbran and Hartlepool .

Basement Insulation

Knauf Insulation provide products suitable for use in both the insulation of new-build basements and refurbishment of existing basements and give options depending on the preferred level of thermal performance.

The systems identified on this page offer maximum protection against possible damp problems as the insulation selected is closed cell and thus highly resistant to both vapour and liquid water. Other wall lining systems could be used for basement walls where the specifier is confident that damp penetration and condensation problems will not occur.

Their main product used in the Conversion of Basements is the Polyfoam XPS Boards as detailled below:

Polyfoam XPS

XPS is an extruded polystyrene insulation manufactured through a plastic extrusion process. The resulting boards are almost 100% closed cell, strong, highly moisture resistant and easy to cut and shape. This makes them ideal for applications in the construction industry as they are 'Site Survivor™s' and can be cut to shapes that make them extremely fit for use. It also means that Polyfoam is ideal for a vast range of fabrication applications where the strength of the material as an infill in panels etc. is widely recognised and valued.

In short Polyfoam is 2 solutions in one......both a thermal AND structural insulation solution. The range includes the following:

  • Polyfoam Floorboard is a high performance, 100% ozone friendly, extruded polystyrene, rigid board insulation. It is lightweight, yet has excellent structural strength and long term effectiveness.
  • Polyfoam Floorboard is available in three grades, Standard, Extra and Super.
  • Polyfoam Linerboard is a laminate of Polyfoam high performance, 100% ozone friendly, extruded polystyrene, rigid board insulation and tapered edge plasterboard.

External Insulation

Knauf External Basement Insulation

External insulation is the preferred option for basements as the whole structure is kept warm, with little risk of condensation. The insulation should be placed up against the waterproofing membrane. Polyfoam extruded polystyrene is recommended because of its low moisture absorption and high compression resistance.
A drainage membrane or layer of washed no fines gravel should be placed over the insulation. This relieves hydrostatic pressure and channels water to the foundation drain. The membrane or gravel should be covered with a geotextile to prevent fines from blocking the drainage material.

Internal Insulation

Knauf Internal Basement Insulation

Internal insulation of basement walls is only recommended for existing basements. New basements should be insulated externally. Polyfoam Floorboard Standard should be fixed directly against the drainage cavity membrane, by ribbons and dabs of plaster adhesive. Joints need to be taped with an aluminium faced self-adhesive tape. The junction between the Polyfoam Floorboard and the surrounding construction should then be sealed with a water resistant, solvent-free silicone sealant.

Loft Conversion Insulation

Knauf Insulation also provide products that offer a number of options for the three main types of construction that are likely to be utilised in a loft conversion. These are sloping and flat ceilings, and timber stud walls.

Further details about the above, and the full range of Knauf Insulation's products and solutions can be found on their website:



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