Rockwool Flexi - is a multi-use, dual purpose thermal and acoustic insulation product with a unique flexible edge along one side. The flexible edge ensures a perfect fit is maintained between the product and its supporting framework for optimum effectiveness.
Flexi slabs ensure essential tight fitting for thermal and acoustic integrity between frames in walls, partitions, floors and roofs, without the need for cutting or waste. Made from renewable volcanic rock, they are extremely fire resistant and significantly reduce the carbon footprint of a building.
Rockwool Flexi is a product that consists of a semi-rigid slab with a flexible edge along one side. Rockwool Flexi is stone wool, or rock, insulation product with a flexible edge along one side, to ensure a perfect fit every time, within floor joists, between rafters, metal and timber studs and metal and timber frame buildings.
This ingenious volcanic rock slab with the patented flexi-edge that makes installation so easy.
Unlike rigid insulants, Rockwool Flexi will hold itself within the stud centres required, first time, every time. Timber expands and contracts,
Rockwool Flexi can be fitted between damp timber and will expand into the wider space created when the timber has dried out and shrunk back ... while other rigid or very flimsy insulants may fall out or be displaced, resulting in cold spots and poor acoustics.
Rockwool Insulation needs to deliver good thermal performance and avoid unplanned thermal bridges. It is not enough to have a product with a good thermal performance, if it is difficult to install it without gaps, cracks or other insulation errors in the final construction. Therefore the insulation must be easy to install to achieve an exact fit in the construction.
Avoiding unplanned air gaps is even more relevant, as the insulation efforts on the building envelope are increasing and the relative effects of unwanted air-gaps are consequently becoming bigger. This is particular true for exterior wall insulation systems, where mortar penetrating the insulation layer can add a substantial, unplanned thermal bridge to the construction.
For indoor use, lightweight Rockwool insulation products are manufactured with slightly flexible edges. This allows them to knit together at the joints and fit closely into building structures without leaving unplanned gaps.
Patented ‘flexi’ edge offers accurate fit to all widths
Will not slump, even if studs shrink
Fits all typical metal and timber frame spacing
Excellent thermal, acoustic and fire properties
Non-combustible (Euroclass A1)
Easy to handle and install
Superior fit with no waste
Product Properties and Performance
Sizes: 600mm x 1200mm slabs and 400mm x 1200mm sizes
Thickness’s: 25, 50, 75 and 100mm
Rockwool Flexi® has a thermal conductivity of 50 – 120mm, 0.038 W/mK when tested to EN13162.
At 140 mm thickness, it has a thermal conductivity of 0.035W/mK.
Refer to the Rockwool Flexi datasheet for U Values.
Rockwool Flexi works in two distinct ways to reduce noise, either by impeding the transmission of sound through an element of the structure, or by absorption of sound at the surface. Noise absorption is expressed as a factor between 0 and 1.0. The more sound that a surface absorbs, the higher its absorption coefficient. The structure of the fibres in these slabs make them ideal for use as a sound absorber, with characteristically high coefficients over a wide frequency range.
Rockwool Flexi achieves a reaction to Fire classification of A1, as defined in EN13501-1.
Refer to datasheet for relevant fire rated constructions.
Specifically for details about the Rockwool Flexi 1 Hour fire floor and fire rated internal partition. Refer to the Application Guide for construction information.
Green Guide Rating
Rockwool Flexi corresponds to the BRE Global Green Guide online generic specification ‘Stone wool insulation - density 45 kg/m³ ’ (ref. 815320008) which achieves a summary rating of ‘A+’ within all building types.
All Rockwool stone wool insulation repels liquid water due to its fibre orientation and the presence of water repellent additives.
Third Party Approvals
Rockwool Flexi has the following certifications: LBCB 022E (Loss Prevention Certification Board) KM 06661 (KiteMark) LUL (London Underground Limited) CE Mark
Ozone Depleting Potential
Relying on entrapped air for its thermal properties, we are proud to say that ROCKWOOL FLEXI® does not contain (and has never contained) gases that have an ozone depleting potential (ODP).
Global Warming Potential
Relying on entrapped air for its thermal properties, we are proud to say that ROCKWOOL FLEXI® does not contain (and has never contained) gases that have a global warming potential (GWP). Therefore, they have a zero GWP for the purposes of rating schemes such as the Code for Sustainable Homes.