Flat roofs are a distinguishing feature of many modern buildings. They offer the possibility of both minimising the enclosed volume and maximise the planning envelope in volume terms. 

The selection of the insulation is driven by various design parameters that may include thermal, acoustic and fire performance and environmental requirements.

Rockwool roofing boards easily fulfil and can exceed thermal requirements as required by building legislation, including The Approved Document L (England & Wales) and Part J (Scotland).  

To comply with building regulations and as part of the design process, you may need to submit SAP calculations to Building Control. If you require more information on SAP 2005 we suggest you visit the BuildDesk website. BuildDesk produces the leading SAP 2005 software tool, BuildDesk Energy Design, together with training and consultancy. BuildDesk is a member of the Rockwool Group

Fire

Rockwool roofing boards offer exclusively a high level of fire safety. When tested under the new EU linings fire classification system – for non combustibility to EN ISO 1182 and/or Gross Calorific value to EN ISO 1716, they achieve the best A1 classification.

Roofing constructions incorporating Hardrock Dual Density roofing boards have achieved the highest possible classification to LPS 1181:Part 1 (i.e. EXT-A). This was accomplished by successfully undertaking and passing the Part 1 test for reaction to Fire and the more onerous LPS 1208 Resistance to Fire test. Rockwool roofing boards are the only insulation products to have achieved this classification with respect to built-up warm flat roofing constructions.

This superior fire rating has an even greater significance with the new Regulatory Reform (Fire Safety) Order that came into force in October 2006.

Insurance requirements for Protected zones 
External roof areas adjacent to ‘Protected zones’ as defined by the ‘LPC Design Guide for the Fire Protection of Buildings’ are required to meet the fire resistance requirements outlined by Appendix B, LPS 1181: Part 1. This allows for three levels of fire resistance EXT -A15, EXT -A30 & EXT -A60 depending on the outcome of the risk assessment. See LPS 1181: Part 1 Appendix B and LPC Design Guide for the Fire Protection of Buildings (Table 2.2) for specific details. Systems that have only achieved EXT-B Grade are not suitable for use in ‘protected zones’ and will not Comply with the insurance industry standards in these locations.

Building Regulations Approved Document
Where a flat roof is to be used for escape purposes, the construction must achieve a minimum fire resistance of 30 minutes integrity and insulation (i.e. EXT-A30).

Acoustic
Effective sound insulation is also an essential requirement where commercial or industrial operations generate noise at levels, which could be harmful to the health or efficiency of the building occupants, or present an environmental nuisance.

Rain Noise
Impact noise from rain must be considered at an early part in the roof design, due to the fact that this can significantly increase the indoor noise level. Approved Document E–Resistance to the passage of sound, 2004 Addition, requires the construction of new school buildings to meet appropriate acoustic standards. Building Bulletin 93 outlines the methods of compliance. This includes a requirement to minimise the noise of rainfall on lightweight roofs and whilst no limit is set, methods of control must be included and justified to Building Control.

BREEAM Schools 2006
The Building Research Establishment Environmental Assessment Method (BREEAM) Under Health and Wellbeing, Acoustic Performance (HW17), stipulates that credits will be awarded for new build and refurbishment projects where the indoor ambient noise levels (defined in table 1.1, BB93) during ‘heavy’ rainfall are exceeded by no more than 20dB in the design calculations. For lightweight flat roof constructions, this most onerous requirement may be achieved by a combination of Hardrock Dual Density roofing boards, Rockfon acoustic ceilings and Rockwool Flexi overlay insulation.

The control of noise pollution is an ever-increasing problem. The solution tends to be specific to each building and is dependent on the type and source of the noise. Find out more with Rockwool  SoundPro range.

Hardrock dual density roofing boards are proven to be the ideal acoustic insulation material for use in warm flat roof constructions. The use of Hardrock dual density roofing boards in conjunction with perforated steel decking provides sound absorption within the building, thereby improving the environment for work and leisure.

Noise intrusion from heavy traffic or aircraft can be reduced by using Hardrock Dual Density roofing boards as part of the roof system, creating a quieter ambience within the building. The product may alternatively be used to assist containment of the noise source within the same building.

For High performance acoustic specifications, the use of a mass layer may be required. The combination of Hardrock Dual Density and Rockwool Acoustic Membrane (RAM) results in improved sound insulation levels across the frequency range.

Hardrock dual density roofing board when used within a flat roof construction including a profiled metal deck and single ply membrane provides significant acoustic improvement with respect to the impact noise from rain. An improvement of up to 10dB is achieved, which in acoustic terms is perceived by the human ear as halving the audible rain noise.     

Rockwool Acoustic membrane is a flexible, high-density polymer mass layer with inherent acoustic damping properties. Used in combination with Hardrock dual density roofing board, it is used to attain the highest acoustic performance levels for lightweight flat and built up metal roof constructions. These include cinemas, airports, concert halls, stadia, retail and leisure developments, call centres, schools, etc.

Rockwool roofing boards are manufactured using Rockwool’s unique dual density technology. Produced with a robust high-density top surface, the products therefore exhibit excellent point load, compressive and impact resistance. The products are easy to work and cut on site with a saw or broad bladed knife. For mechanically fastened single ply membrane applications, only one insulation fastener is required per board, thereby offering faster and easier site installation.

Rockwool Acoustic Infill
Rockwool Acoustic Infill consists of a trapezoidal shaped tissue faced Rockwool insulation, engineered to suit specified perforated roof decking. mainly used at flat roof areas over convention and sports halls, manufacturing plants, entrance halls, corridors, hallways and stairwells etc.

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