Thermafleece UltraWool – High Density Sheep's Wool Insulation
Thermafleece UltraWool – High Density Sheep's Wool

Key Facts

  • Width (mm) – 390, 590
  • Thickness (mm) – 50, 70, 90
  • Thermal Conductivity – 0.035 W/mK
  • Sound Absorption – NRC 1.10 @ 90mm
  • Highly Breathable
  • Made in the UK
  • Contains British Wool
  • Can be recycled

Thermafleece UltraWool – High Density Sheep's Wool

Rich in British sheep’s wool - designed to give extra thermal performance where depth is limited and our highest level of acoustic performance

Thermafleece UltraWool is a high density, highly efficient insulation made from 75% British sheep’s wool and  25% recycled polyester. UltraWool is the ideal choice if you are looking for maximum thermal performance when space is at a premium. What’s more, with a density of 31 kg/m3 Thermafleece UltraWool helps provide exceptional acoustic insulation performance in wall, floor and roof systems.

Research shows that using 75% wool in combination with recycled fibres outperforms alternative products with a higher percentage of wool. Our wool rich blend ensures you get the full benefit of sheep’s wool with enhanced performance, breathability, durability and sustainability.

Installing Thermafleece

Thermafleece UltraWool is harmless and can be installed without gloves or protective clothing, although we recommend you wear a dust mask in enclosed spaces such as lofts. Thermafleece UltraWool is not irritating to the skin, eyes or respiratory tract.

To retain the benefits of water vapour, absorption and release, Thermafleece UltraWool may be used in conjunction with a vapour permeable underlay. Protect the insulation from prolonged exposure to sunlight when unpacked and avoid wetting for extended periods, store under cover and clear of the ground.

Cutting Tips

Thermafleece UltraWool can be safely and easliy torn apart, but if you need a more accurate edge then we recommend the 'Roll and Cut' Method

Tools Required: Sharp Scalloped Edge Knife or Insulation Saw

1. For an accurate length, take the insulation and  roll it as tightly as possible along the width. Measure where you need to cut then taking the insulation saw / knife  easily cut through. This provides a nice, neat edge and is an alternative to tearing by hand.
2. To cut the width of the slab: Roll the insulation tightly along the length and secure. Measure the required width that you need then using the knife or insulation saw begin to cut through the whole roll.  

Take a look at the video on YouTube or download the How To Cut Application notes

You can also cut Thermafleece by tightly compressing or clamping the insulation between two pieces of solid 15mm board. Overhang the fleece where you want to cut keeping the two board edges aligned. Saw cut the edge using a sharp, scalloped edged knife and keep the blade firm and square against both board edges throughout. Trim any fine remaining fibres with large scissors or shears.


  • Thermal Conductivity: 0.035 Wm-1K-1
  • Water Absorption (@100% RH): 24% w/w
  • Specific Heat Capacity: 1800 Jkg-1K-1
  • Mould Resistance - CUAP 2002-01-25: Pass
  • Moth/Beetle Proofing - ISO 3998: Pass
  • Vapour Resistivity: 9 MN·s·g–1m–1
  • BS 5803-4, Flammability & Smoulder Resistance: Pass
  • EN11925-2, Reaction to Fire: Pass
  • Fire Classification: EuroClass E
  • Recoverability and thickness, EN 823: Pass
  • Dimensional stability to EN 1604: Pass
  • Can be used to achieve airborne sound reduction of Rw = 41dB
  • GWP (A1-A3): 1.63 kgCO2e
  • GWP (A1-A3) inc. biogenic carbon: 0.59 kgCO2e
  • Recycled Content: 20%
  • Recyclable: Yes

Featured buildings

Apple Tree Farm House Apple Tree Farm House
Blacksail YHA Blacksail YHA
Bodleian Library Bodleian Library
Bowman's Lea <br>ASBP Award Winner Bowman's Lea
ASBP Award Winner
Box House - Studio Bark Box House - Studio Bark
Brighton Dome Brighton Dome
Burnhead Bothy Burnhead Bothy
Canterbury Cathedral Canterbury Cathedral
Flitwick Mill Flitwick Mill
Mill Lane, East Sussex Mill Lane, East Sussex
North Woods Design North Woods Design
Pitlyal Byre Pitlyal Byre
PlankBridge Fine Huts PlankBridge Fine Huts
Rocket Caravans Rocket Caravans
Sunbeams Music Centre Sunbeams Music Centre
Sweeney's Bothy Sweeney's Bothy
Two Flowers Croft Two Flowers Croft
Design: The Space