Topsleeve | Natural Wool Pipe Insulation
by Global Intl Ltd — ISO 9001 & ISO 14001 Certified — Euroclass C Fire — 7.2m Rolls
Topsleeve is a range of natural sheep wool felt pipe insulation manufactured in the UK. Unlike conventional grey polyethylene foam lagging, Topsleeve is made from 80% wool and 20% mixed fibres, giving it a unique combination of thermal insulation, acoustic damping, moisture management, and natural fire resistance — without any chemical flame-retardant treatment. The wool self-extinguishes when removed from a flame source and will not support free combustion.
Topsleeve is available in three forms: a slip-on sleeve for 15–22mm pipes, a slip-on sleeve for 22–28mm pipes, and a universal wrap-round for any pipe size or multiple pipes at once. All three are supplied as 7.2m rolls (24 ft) and are particularly valued for their flexibility in tight spaces, around joints and elbows, and on complex pipework runs where rigid foam sections would be difficult or impossible to fit.
Natural Sheep Wool Euroclass C Fire Rating ISO 9001 & ISO 14001 Acoustic Insulation Dust-Free & Safe to Handle Recyclable & Biodegradable
Variant Selection Guide
Three variants are available. Choose the slip-on sleeve that matches your pipe diameter, or select the universal wrap-round for larger pipes, multiple pipes together, or particularly awkward runs.
| Variant |
Product Code |
Width |
Roll Length |
Pipe Size Coverage |
Linear Pipe Coverage |
| Slip-On Sleeve 15/22mm |
SPL-15-22 |
50mm |
7.2m (24 ft) |
15mm and 22mm pipe |
~3m per roll |
| Slip-On Sleeve 22/28mm |
SPL-15-28 |
70mm |
7.2m (24 ft) |
22mm and 28mm pipe |
~3m per roll |
| Universal Wrap-Round |
SPL-WRAP4 |
100mm |
7.2m (24 ft) |
Any pipe size — including 35mm+ and multiple pipes |
~4m (15mm) / ~3m (22mm) per roll |
* Linear pipe coverage figures are approximate and depend on pipe diameter and wrapping overlap.
How Each Variant Works
Slip-On 15/22mm — SPL-15-22
A 50mm-wide wool felt sleeve pre-formed as a tube. For new installations, slide the sleeve along the pipe before connecting fittings. For existing pipework, scrunch the product to open the sleeve, position it around the pipe at a joint or end, then smooth it along the run. The flexible wool material scrunches and recovers around elbows, tee pieces, and fittings without cutting. Ideal for 15mm and 22mm copper or plastic pipe.
Slip-On 22/28mm — SPL-15-28
A wider 70mm-wide wool felt sleeve for the larger 22mm and 28mm pipe diameters used on central heating flow and return circuits, boiler connections, and cylinder pipework. Same application method as the 15/22mm sleeve — scrunch to open, position at a joint or free end, smooth along the run. Also effective for pair-insulating a 15mm flow and return running close together.
Universal Wrap-Round — SPL-WRAP4
A 100mm-wide flat wrap for any pipe size, any number of pipes, and configurations where a sleeve cannot be slid on. Position the end of the wrap against the pipe and spiral along its length, overlapping by 50mm (50% overlap) as you go. Can be wrapped around a pair of pipes simultaneously. When complete, tuck the ends securely behind the pipework. Suitable for 35mm pipe, multi-pipe bundles, and complex valve and fitting clusters.
Installation tip: All Topsleeve slip-on variants can be installed on existing pipework without disconnecting — scrunch and stretch the sleeve over a tee fitting or valve to access the pipe run, then smooth the felt along the pipe. The wool construction gives enough stretch to navigate most domestic pipework layouts without cutting.
Technical Specifications
| Property |
Value |
Standard / Note |
| Material composition |
80% wool, 20% mixed fibres |
Needled felt construction |
| Colour |
Variable grey / multi-fleck (natural wool) |
Colour may vary between batches |
| Thermal conductivity @ 10°C |
λ = 0.033 W/mK |
Topsleeve test report |
| Thermal conductivity @ 60°C |
λ = 0.039 W/mK |
Topsleeve test report |
| Fire classification |
Euroclass C |
BS EN 13501-1:2007+A1:2009 |
| Smoke classification |
Euroclass C |
BS EN 13823:2010 |
| Flammability behaviour |
Self-extinguishing — chars and stops burning when flame removed |
No chemical flame-retardant treatment |
| Moisture absorption |
Up to 30% of own weight without feeling damp |
Hygroscopic — absorbs and releases moisture vapour |
| Appearance / form |
Solid fibrous — pre-formed sleeve or flat wrap |
Odourless |
| Dust during handling |
Dust-free |
No PPE or respirator required for normal handling |
| End-of-life |
Recyclable and biodegradable |
Zero ozone depletion potential |
| Quality certification |
ISO 9001:2008 / ISO 14001:2015 |
Global Intl Ltd |
| Manufacturer |
Global Intl Ltd (Topsleeve brand) |
Hainault Business Park, Ilford, Essex IG6 3UT |
Key Features & Benefits
Frost and freeze protection
Wool insulates against both heat loss and cold ingress. The thermal barrier created around the pipe significantly raises the time to freezing, protecting vulnerable loft and external wall pipework through cold spells.
Moisture management
Wool fibres absorb up to 30% of their weight in moisture vapour without feeling wet, buffering humidity fluctuations and helping to prevent surface condensation on cold water pipes by maintaining a dry micro-climate around the pipe.
Natural fire resistance
Wool's naturally high moisture and nitrogen content makes it inherently fire resistant without chemical additives. It chars on contact with flame but self-extinguishes once the ignition source is removed, achieving Euroclass C without synthetic treatments.
Acoustic damping
Wool is a superior acoustic absorber. Topsleeve reduces the transmission of flow noise, expansion and contraction sounds, and structural noise from heating and plumbing pipework running between floor and wall cavities.
Ideal for tight and complex spaces
Unlike rigid foam sections, Topsleeve conforms to elbows, tee pieces, valves, and close-centred pipe runs. Particularly effective in airing cupboards, under-sink spaces, and cavity walls where foam lagging is impractical.
Sustainable and low-impact
Made from a renewable, naturally produced fibre, Topsleeve requires less than 15% of the energy used to manufacture glass fibre insulation. It is recyclable after use, biodegradable at end of life, and has zero ozone depletion potential.
Typical Applications
Loft pipework frost protection
Domestic heating flow & return pipework
Hot and cold water services
Elbows, tee pieces, and valve bodies
Airing cupboards and under-sink spaces
Multiple adjacent pipes running together
Larger bore pipes (35mm+) using wrap-round variant
Infill and gap insulation alongside foam lagging
Topsleeve Wool Felt vs Polyethylene Foam Lagging
| Property |
Topsleeve Wool Felt |
Polyethylene Foam (e.g. Tubolit DG) |
| Material origin |
Natural — sheep wool |
Synthetic — extruded polyethylene |
| Thermal conductivity |
0.033 W/mK @ 10°C |
0.035 W/mK @ 0°C |
| Fire classification |
Euroclass C — self-extinguishing |
Euroclass E — no ignition |
| Moisture behaviour |
Hygroscopic — absorbs and releases moisture vapour |
Hydrophobic — repels moisture |
| Fit to elbows/fittings |
Excellent — stretches and conforms |
Requires mitred cuts and taping |
| Multiple pipes at once |
Yes — wrap-round variant |
No — individual pipe sections only |
| Acoustic performance |
Superior — wool absorbs sound |
Moderate — some damping |
| End-of-life disposal |
Recyclable and biodegradable |
Recyclable — not biodegradable |
Frequently Asked Questions
Which variant do I need — the 15/22mm sleeve, the 22/28mm sleeve, or the wrap-round?
For 15mm or 22mm copper or plastic pipe, choose the SPL-15-22 slip-on sleeve. For 22mm or 28mm pipe — typically boiler flow and return, cylinder connections, and main heating circuits — choose the SPL-15-28 sleeve. For 35mm or larger pipes, for pairs of pipes running close together that you want to insulate as one, or for particularly complex valve and fitting clusters, choose the SPL-WRAP4 universal wrap-round.
Can Topsleeve be fitted to existing pipework without disconnecting it?
Yes — this is one of Topsleeve's main advantages over rigid foam lagging. The slip-on sleeves can be scrunched and stretched to access an existing pipe run via a joint, valve, or pipe end; the wool construction allows enough deformation to work the sleeve along the pipe and around elbows. The wrap-round variant is even simpler — it spirals around the pipe from any starting point with no access to the pipe end required.
How much pipe does one roll cover?
Each roll is 7.2m (24 ft) long. The slip-on sleeves (SPL-15-22 and SPL-15-28) cover approximately 3 linear metres of pipe per roll, as the sleeve folds back on itself to create a double-walled insulating tube around the pipe. The universal wrap-round (SPL-WRAP4) covers approximately 4 metres of 15mm pipe or 3 metres of 22mm pipe per roll when applied with a 50% overlap. All figures are approximate and vary with pipe diameter and fitting complexity.
Is Topsleeve suitable for outdoor or heat pump external pipework?
Topsleeve is primarily designed for indoor plumbing and heating applications. As a natural wool product it will absorb moisture if left exposed to rain and, unlike closed-cell foam, is not inherently waterproof. For external heat pump pipework and outdoor pipe runs requiring permanent UV and weather resistance, a product specifically rated for external use — such as Primary Pro pipe insulation — is the appropriate choice. Topsleeve can be used in sheltered external spaces provided it is protected from direct rain and prolonged wetting.
Is wool pipe insulation fire safe?
Yes. Topsleeve achieves Euroclass C to BS EN 13501-1, which is a higher fire classification than standard grey polyethylene foam pipe lagging (Euroclass E). Wool does not require chemical flame retardant additives — its natural moisture and nitrogen content make it inherently self-extinguishing. When exposed to a flame, it chars rather than melting or dripping, and stops burning as soon as the ignition source is removed.
Related Products:
Tubolit DG Polyethylene Pipe Insulation (15mm, 22mm, 28mm — 1m lengths) | Primary Pro Heat Pump Pipe Insulation Range (UV-stable, external use) | Intatec ZERO28 Anti-Freeze Valve | Intatec ZEROGUARD Anti-Freeze Valve Protector | Primary Pro AS32 Anti-Freeze Valve Insulation Shell
