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Black Mountain NatuWool Sheep's Wool Insulation

EPS70 Expanded Polystyrene the high compressive strength under floor rigid insulation

Black Mountain's manufacturing facility dedicated to producing natural environmentally friendly insulation product is located here in the UK. The sheep’s wool used in production of NatuWool is a by-product of other industries and the minimal binder used contains recycled material.

Product Applications

Black Mountain use up to 90% less embodied energy in comparison to many man-made insulation products, the wool used in their products permanently absorb significant quantities of carbon dioxide during their growth cycle. Therefore, this natural fibre insulation is ‘carbon negative’ – locking up a substantially higher level of carbon than used during their manufacture.

Not only do natural insulation products, such as sheep’s wool insulation, have an extended life span in comparison to many man-made alternatives, they can still be composted or recycled at the end of their life span. Landfill sites are not a sustainable option for truly sustainable products.

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Price and Availability Information

Presently there are no availability restrictions, apart from manufacturing lead-times and minimum quantity order levels on certain product sizes.
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Product availability depends upon stock levels at closest depot and delivery logistics to geographic locations

Product Advantages

  • NatuWool Sheeps Wool Insulation installation on the interior of an external wallNatural fibre thermal insulator
  • Content 95% natural wool fibres
  • Five percent combination recycled adhesive binder
  • Originates from wools unsuitable for other industries
  • The structure is flexible, resilient and versatile
  • Easy to cut and shape for exact fix
  • Black Mountain sheep’s wool insulation is an excellent thermal insulator and offers a thermal conductivity of 0.039 W/mK.
  • Rolls are ideal for use in cold lofts and suspended floor spaces as they save time during installation and there is less opportunity for ‘cold spots’ to occur.
  • Batts are recommended for use in warm loft application, partitioning wall space and timber frames to avoid potential movement and provide an easy fit.

  • Black Mountain NatuWool loft conversion application The sheep’s wool used in production of NatuWool is a by-product of other industries and the minimal binder used contains recycled material. Although many companies claim their products reduce energy consumption and improve thermal efficiency, this is true for all insulation products and is a poor means of differentiation.

Product Specifications

Standard Roll Sizes

  • Thickness 50mm, 75mm, 100mm, 125mm | Length = 4m, 5m, 7.5m and 10m | Width 600mm
  • Square metres per pack = 2.4m2, 3m2, 4.5m2 and 6m2
  • Special sizes and thickness are available on request

Standard Batt / Slab Sizes (POA)

  • Thickness 50mm, 75mm, 100mm, 125mm, 150mm, 200mm, 250mm | Length = 1200mm | Width 400mm or 600mm
  • Square metres per 400mm slab = 0.48m2 - Per 600mm slab = 0.72m2
  • Special sizes and thickness are available on request

Technical Standards

  • Thermal conductivity (λ) 0.039 W/mK
  • Thermal resistance (R) (100mm) 2.50m2K/W
  • Specific heat capacity (c) 1700 J/kg2K
  • Vapour resistivity (r) 10 MNs/gm
  • Moisture absorption 35% w/w<
  • Condensation BS 5250:1989
  • Fire Euro Class E - EN 13501-1:2002
  • ODP (Ozone depletion potential) Zero
  • GWP (Global warming potential) Zero

Thermal Performance

Density 19kg /m3



Thermal (R) U Value


1.28 m2k/W

0.78 W/m2K


1.92 m2k/W

0.52 W/m2K


2.56 m2k/W

0.39 W/m2K


3.85 m2k/W

0.26 W/m2K


5.13 m2k/W

0.20 W/m2K


6.41 m2k/W

0.16 W/m2K

Product Characteristics

Thermal Efficiency

Black Mountain sheep’s wool insulation is an excellent thermal insulator and offers a thermal conductivity of 0.039 W/mK.

Moisture Absorbency

Sheep’s wool insulation has the capacity to absorb and manage over 35% moisture without having a detrimental impact on product performance.

Volatile Organic Compound Absorption (VOC)

Sheep’s wool has a unique ability to absorb and lock away noxious gases that are emitted by various building products.

Flame Resistant

  • Sheep’s wool insulation is classified as fire resistant and in the case of a fire will not exacerbate the situation. Achieving a Euro Class E fire performance rating, which ensures that the material is flame retardant.
  • The wool is washed and treated to make it fire safe. This means that the product will not cause or exacerbate a fire.

Condensation Control

  • Condensation is one of the biggest challenges facing the building industry today. Excess moisture can not only have a detrimental effect on the structure of a building but it is also a root cause of mould which can have an adverse affect on them welfare of its inhabitants.
  • NatuWool is a hygroscopic fibre and is therefore able to absorb, store and release moisture faster than most other materials. It can absorb over 35% of its own weight in moisture without significant changes to thermal performance, whereas the thermal performance of man-made mineral fibre insulation deteriorates when condensation is present.
  • Sheep’s wool insulation is ideally suited to timber frame structures as it has a natural synergy with wood. The sheep’s wool fibres draw out the moisture, conditioning the wood and act as a ‘buffer’ to protect the fabric of the building.
  • Independent research clearly illustrates that as moisture levels increase, no significant changes to thermal conductivity will occur. This consistency demonstrates the versatility of sheep’s wool insulation and an ability to cope in contrasting environments and levels of humidity.

Installation & Application

NatuWool insulation is flexible and ideal for use in confined spaces. This ease of use makes the installation process faster and more efficient. Black Mountain sheep’s wool insulation is ideally suited to timber frame structures and can be applied to Lofts, Rafters, Walls and Floors.

Cold Roof

Households commonly use lofts for storage and therefore do not need to be heated. The heat lost through an uninsulated loft is approximately 20% of the energy which is required to heat a typical house. In order to avoid energy escaping into unused loft space, it is recommended that insulation is applied between the joists on the floor of the loft. To maximise insulation efficiency, a minimum thickness of 250mm is recommended.


  • Measure the gap between the joists to determine the appropriate widths necessary.
  • The first layer of insulation should fit snugly between the joists to avoid gaps from occurring.
  • To prevent heat escaping through the timber joists we recommend that the insulation is installed in layers at 90°angles.
  • Black Mountain manufactures special widths to ensure that no gaps are present and heat loss is therefore minimised.

Additional information

  • Cutting - Black Mountain sheep’s wool insulation is easy to tear across the width of the product. Alternatively hold the material taut between two planks of wood and use a sharp blade or a pair of scissors to cut.
  • Ventilation - when installing the insulation at the eves of the loft, ensure that a small gap or a vent tray is left to allow for regular air movement. This helps to prevent condensation build up.
  • Loft boards - when applying insulation into loft joists we recommend that secure boards are put in place across the joists for safe working conditions and loft access.
  • Light covers - where exposed lighting fixtures are present, it is important to ensure that there is no direct contact with the insulation and that any additional wiring is placed over the top of the insulation to prevent
  • overheating.
  • Storage - if loft space is used for storage then a raised floor section should be applied to an appropriate area of the loft.
  • Recovery - Black Mountain compress their products to reduce embodied energy, however, the product will regain its full thickness within 72 hours.

Warm Roof

Loft renovations are an increasingly popular means of maximising property value and space. Natural insulations are ideal solutions for attic conversions due to their unique ability to manage moisture.

The most critical aspect of insulating a warm loft is to understand the type of roof structure. There are two types of roofing felt present in most households; ‘breathable membrane’ and older bitumen based ‘non-breathable membrane’.

Installation - Breathable Membrane

  • The insulation should be applied up to current building regulations of 225mm.
  • If the rafters do not meet this depth then battens should be applied to increase the depth and meet the required thickness.
  • Staple the material to the timber rafters or fix string across the material to prevent the insulation from falling out.
  • Alternatively mesh netting can be used to maintain the position of the insulation once installed.
  • To complete the installation, plasterboard should then be applied and a vapour barrier where necessary.

Installation - Non-Breathable Membrane

  • The key difference between a breathable membrane and the older bitumen membrane is the 50mm ventilation gap required for non-breathable membranes.
  • This gap allows any moisture absorbed by the insulation to pass through the material and evaporate through circulating air currents.
  • To ensure the 50mm gap is maintained, the insulation can be stapled to the edge of the rafters which will help prevent it slumping into the cavity.
  • Alternatively wire mesh can be applied to the sides of the rafters which will ensure that the ventilation gap is maintained.

Timber Frame Walls

The construction of timber frame buildings continues to grow throughout the UK and much of Europe.

Natural insulations are ideally suited to timber frames, drawing out excess moisture and conditioning the wood which helps prevent structural damage in the future.

Installation - Outer Layer

  • The key components to include when constructing an external timber wall are:
  • Breathable membrane.
  • OSB or other suitable sheathing boards.
  • To further increase the thermal efficiency of the structure, it is recommended that ‘reflective’ breathable membranes are used, which are available from leading manufacturers.
  • The cavity between the outer brick skin and the breathable membrane should not be filled with additional insulation.
  • It is important that the breathable membrane is exposed to circulating air currents.
  • After measuring the ‘drop length’, select the measurements that are required or alternatively cut the insulation from the rolls or batts.
  • The insulation is simply pressed between the stud framework as the timber is rough enough to catch the material and hold it in place.
  • If the ‘drop length’ is extensive it may be beneficial to staple the insulation to the top wall plate and every ó meter to prevent it from falling out during installation.
  • Once the insulation has been fitted then the vapour barrier and plasterboard can be applied to complete the structure.
  • Alternatively, plasterboards with incorporated vapour barriers are available to simplify the installation process.


A key source of heat escaping in houses is through the floors; this can account for up to 10% of the total energy losses. The high level of heat loss is because many households are unaware whether they have floor insulation and are not conscious of the benefits a properly insulated floor can provide.

Installation - Access From Below

  • If there is a cellar or a crawl space under the floor then the installation process is quick and straight forward:

  • Where necessary, remove a section of the floor boards to gain access to the crawl space.
  • Measure the distance between the joists.
  • Select a width of insulation that is wider than the measured distance to ensure that there will be no gaps.
  • Insert the insulation between the joists, ensuring that there are no gaps present when butting two pieces of insulation together.
  • Staple the breathable membrane or plastic mesh to the underside of the joists to hold the insulation in place.

Installation - Access From Above

  • Where access below the flooring is not available, floorboards and panels should be removed in order to allow access from above:
  • After the floorboards have been removed, ensure that all nails are also removed from the top surface of the joists.
  • Take a roll of breathable membrane and staple the edge to the top of the first joist.
  • Following this, staple the membrane to the bottom of the first joist then spread the material across to the adjacent joist and staple to the bottom of the second joist.
  • Continue to ‘wrap’ the membrane over the top of the second joist and repeat until all joists are covered.
  • Install the insulation to the required depth.
  • When the insulation is in place, apply additional breathable membrane over the surface of the joists and the newly installed insulation to avoid any dust or liquids damaging the insulation.

Product Information and Certification

Links to manufacturer's information. Click to download in a separate browser window.

IPP Black Mountain Natuwool Brochure



Sheep wool insulation matches the following standards for loft, rafter and internal wall thermal requirements as follows:


England/Wales Approved Document
L1, L2 – Table 1
Scotland Technical Standard
Table J23
Northern Ireland Technical Booklet
F –Table 1.2/1.4

Performance & Technical Standards

Fire BS 5803-4:1985
Euro Class E
Condensation BS 5250: 1989
Thermal Conductivity 0.039 W/m°K
Density 19 kg m³
ODP* Zero
GWP* Zero

Priced on Application:

Generally, Products are readily available

Estimates for large quantity orders can be priced on application. Please contact us to discuss such matters.

Contact us directly for further information: Telephone 0333 9000 989  - Email: Click Here:

Manufacturer's Contact Details

Kay Metzeler EPS70 Expanded Polystyrene the high compressive strength under floor rigid insulation

IPP Building Products Limited

Black Mountain Insulation Divisions

Bradwell Hall, Bradwell on Sea, Essex CM0 7HX

Telephone: 01621 776252



Web presence: Black Mountain Insulation

Our Contact Details

Sales Office only:
Insulation Online Limited, 39 Normandy Road
, Worthing, West Sussex, BN14 7DX

Telephone: 0333 9000 989

Facsimile: 0333 7000 797


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