LOFT SLABS

Loft insulation slab also referred to as 'loft board' is a great space-saving option, manufactured in sheets that are pre-cut to fit between any joist spacing to provide extra insulation within your pitched roof. Boards will boost thermal performance, improve acoustics and insulate between rafters. It’s recommended for pitched roofs that you go for moisture-resistant loft boards as standard just as a precaution. Slabs are provided in sizes that are easily transportable and good for handling measuring 1200mm x 600mm. In England, the required minimum U-value for pitched roofs insulated at rafter level is 0.18 W/m²K or lower. This equates to a 175mm of slab insulation. The regulations don’t specify which material is used – there is a range to choose from and each will have different thicknesses to achieve the minimum U-value. Ideally, you want insulation that gives the lowest U-value for the thinnest material so that your headroom is affected as little as possible, or you may want to consider environmentally friendly insulation materials. Insulation slabs are generally added under a vapour control layer, which reduces the risk of mould and condensation forming. If cutting loft slabs always ensure you have the correct protective clothing and equipment on. This includes goggles, to protect dust from irritating your eyes, as well as a dust mask.

MANUFACTURERS

When it comes to best loft insulation boards between the rafters, Rockwool and Knauf are main players in the UK market. InsulationGo is proud to offer a wide range of loft insulation boards, from those well-known industry leaders. Each brand of insulation board is different, because of the materials they’re manufactured out of or because of their core application. General-purpose insulation boards such as RWA45, RW5 or RW3 are perfect for many standard applications. These types of boards can be used in pitched roofs, ceilings, floors and walls thanks to their sturdy makeup and their easy installation. 
Offering a number of different ranges of insulation boards, Knauf have ensured that they have created a product for every possible situation. 
Knauf insulation boards can be used in both the ceiling or pitched roof sector to improve the insulation. Knauf insulation slabs are continuously developing, using their years of experience and high-quality innovation to create double foil facings that provide maximum heat resistance. On other hand, Rockwool is one of the most well-known brands around when looking for insulation loft slabs. With an incredibly wide range of different insulation boards, including their popular RWA45, Rockwool insulation boards have been designed for use by contractors and DIYers, specifically for the construction industry in both domestic and commercial builds. Slabs are available in a number of different thicknesses, conductivities and can be used in pitched roofs, flat roofs and floors to ensure the building is well insulated with minimal heat loss.

LOFT INSULATION COSTS

Loft conversions involve time and money and should therefore be carefully considered before going ahead with any plans you may have, and this includes insulation. The cost of insulating a loft will also depend on whether you are going to do the work yourself or hire a professional to do it for you. By fitting insulation slabs yourself you can save a fortune. As of 2022 most popular insulation slab 150mm Rocksilk RS45 Knauf cost £36.36 per m2. Average size roof in the UK measures 70m2. Taking this into consideration you would be paying around £2545 for materials only. If you decide to do it everything yourself, there's no need to worry about the cheapest loft board as you saved money already on labour costs. One thing to remember if you do this yourself is that you should leave a gap between the insulation and the roof slats. This is to ensure that there is enough ventilation to prevent any build-up of condensation and moisture. If any moisture settles in the insulation fabric it will eventually rot.

TYPES OF INSULATION SLABS

Slabs can be supplied either in standard unfaced 1200mm x 600mm size or foil backed on both sides.  Unfaced slabs and foils faced boards offer great fire performance classified as Euroclass A1. These odorless, non-hygroscopic, and rot proof slabs are free of CFCs and HCFCs and will not encourage the growth of fungi, mould or bacteria. Generally speaking, kg/m³ is the weight of the slabs if they were manufactured in a block of one metre cube (1m x 1m x 1m). In order for them to be identified, they are given a density rating which refers to the weight of a metre cube, displayed as kg/m³. Loft insulation is available in a variety of densities which range from 45kg up to 100kg per slab. The greater the mass is, the harder it is to vibrate this material, thus the better the insulating property will be. Therefore, it is better to choose dense and heavy material.

45kg/m³ insulation slabs are the low level insulation density slabs available either from Rockwool or Knauf brand. Although, those slabs still have higher density than other forms of insulation unlike thermal insulation which is lower in density and supplied in rolls. Rockwool RWA45 or Knauf RS45 is named after its density properties in that it has a density of 45Kkg per cubic meter. The 45kg range slabs include the following readily available product thicknesses: 25mm ǀ 30mm ǀ 40mm ǀ 50mm ǀ 60mm ǀ 75mm ǀ 90mm ǀ 100mm 

60kg/m³ acoustic insulation slabs are the middle level insulation density slabs. In fact, it is recommended to use 60kg/m³ slabs as they offer the best insulation value for the money spent. Rockwool RW3 or Knauf RS60 is named after its density properties in that it has a density of 60kg per cubic meter. The 60kg/m³ density slabs are ideal either for loft floors or ceilings to control home acoustics. 60kg density slabs can be supplied either in standard unfaced 1200mm x 600mm size or foil backed on both sides. Unlike unfaced slabs, foils faced boards offer great fire performance classified as Euroclass A1. 60kg range slabs include the following thicknesses:
25mm ǀ 30mm ǀ 40mm ǀ 50mm ǀ 60mm ǀ 75mm ǀ 90mm ǀ 100mm 

100kg/m³ acoustic insulation slabs are the high level insulation density slabs available either from Rockwool or Knauf brand. In fact, it is recommended to use 100kg/m³ slabs in places such as hospitals, auditoriums, stadium acoustics, commercial spaces and doctor offices. Rockwool RWA5 or Knauf RS100 are great examples of high density slabs made especially for commercial and industrial loft spaces.

Video credit:https://www.youtube.com/watch?v=u0BYRb6MHBM&t=85s

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