Armacell | Pipe Insulation
Tubolit® DG — Closed-Cell Polyethylene Foam — EN 14313 — 1 metre lengths
Armacell Tubolit DG is the industry-standard grey polyethylene foam pipe insulation for domestic heating and plumbing installations across the UK. Made from closed-cell CFC/HCFC-free polyethylene foam in accordance with EN 14313, Tubolit DG cuts heat loss on heating pipes, prevents condensation on cold water pipes, and provides a degree of acoustic damping to reduce flow noise in pipework. It is the go-to everyday lagging for central heating, hot and cold water services, and condensate pipe protection in loft spaces.
Tubolit DG is supplied in semi-slit 1 metre lengths that can be snapped directly onto pipework or fully slit by hand for fitting over existing runs. Each length should be fitted with a slight degree of endways compression to ensure joint integrity; all butt joints and seams should be taped or sealed on completion. Available in three bore diameters (15mm, 22mm, 28mm) and two wall thicknesses (9mm, 13mm) to suit the most common domestic copper pipe sizes.
EN 14313 Certified
Euroclass E Fire
CFC / HCFC Free
Semi-Slit — Easy Fit
Reduces Heat Loss up to 80%
Part L Compatible
Variant Selection Guide
Select the bore diameter to match your pipe's outside diameter (OD), then choose the wall thickness appropriate for your application. For central heating and hot water pipes, 13mm wall is the standard specification. For cold water pipes, condensate pipes, or loft frost protection where space is limited, 9mm wall is a practical and cost-effective choice.
| Bore (ID) |
Wall Thickness |
Length |
MPN |
Pipe Compatibility |
Typical Application |
| 15mm |
9mm |
1m |
TL-15/9-DG |
15mm copper / plastic pipe |
Cold water, condensate pipes, loft frost protection |
| 15mm |
13mm |
1m |
TL-15/13-DG |
15mm copper / plastic pipe |
Hot water services, heating system pipework, Part L |
| 22mm |
9mm |
1m |
TL-22/9-DG |
22mm copper / plastic pipe |
Cold water, condensate pipes, loft frost protection |
| 22mm |
13mm |
1m |
TL-22/13-DG |
22mm copper / plastic pipe |
Hot water services, heating system pipework, Part L |
| 28mm |
9mm |
1m |
TL-28/9-DG |
28mm copper / plastic pipe |
Cold water, condensate pipes, loft frost protection |
| 28mm |
13mm |
1m |
TL-28/13-DG |
28mm copper / plastic pipe |
Hot water services, heating system pipework, Part L |
Sizing tip: The bore (ID) of Tubolit DG is sized to match the outside diameter of standard UK copper tube to EN 1057 — 15mm OD, 22mm OD, and 28mm OD. For plastic or pushfit pipe with a different OD, confirm the pipe's OD before selecting a size. Tubolit DG is flexible enough to accommodate minor tolerance variation.
Technical Specifications
| Property |
Value |
Standard / Note |
| Material |
Closed-cell extruded polyethylene foam (PEF) |
EN 14313 |
| Colour |
Silver grey |
— |
| Thermal conductivity @ 0°C |
0.035 W/mK |
BS EN ISO 8497 |
| Thermal conductivity @ 40°C |
0.039 W/mK |
BS EN ISO 8497 |
| Service temperature range |
+5°C to +100°C (surface) |
— |
| Density |
25 kg/m³ |
— |
| Dimensional stability |
2% |
— |
| Fire classification |
Euroclass E |
EN 13501-1 |
| Ozone depletion potential |
Zero |
CFC and HCFC free |
| Global warming potential |
3 |
— |
| Dust / fibre |
Dust-free, non-fibrous |
— |
| Moisture resistance |
Non-hygroscopic, closed-cell structure |
Rot-proof, will not support mould or fungal growth |
| Form / slit |
Semi-slit tube — can be fully slit by hand |
Snap-on or sleeve-over installation |
| Length per piece |
1 metre |
— |
Key Features
Energy saving
Reduces heat loss from exposed heating pipework by up to 80%, lowering energy costs and CO₂ emissions.
Condensation prevention
Closed-cell structure prevents moisture absorption, stopping surface condensation on cold water pipes and protecting against corrosion.
Acoustic damping
Flexible foam reduces the transmission of flow and structural noise from pipework, improving acoustic comfort in the installation.
Hygienic and clean
Non-fibrous and dust-free during installation and in service. Odourless, rot-proof, and will not sustain vermin or encourage fungal growth.
Easy installation
Semi-slit design snaps directly onto pipework. Can be fully slit by hand to sleeve over an existing run without disconnecting pipework.
Environmentally responsible
Manufactured without CFCs, HCFCs, PBDEs, or formaldehyde. Zero ozone depletion potential. Contributes to building energy performance under Part L.
Applications
Tubolit DG is suitable for insulation and protection of pipes in domestic and light commercial heating and plumbing installations, including:
Central heating flow and return pipework
Domestic hot and cold water services
Condensate pipe protection
Loft pipework frost protection
Cavity wall and under-floor pipework protection
Elbows, fittings, and flanges (using slit sections)
Outdoor use: Tubolit DG is not designed for permanent outdoor or UV-exposed use. For short-term frost protection in exposed locations it can be used temporarily, but for long-term external pipe insulation, a UV-stable alternative such as Armaflex Tuffcoat or Primary Pro pipe insulation should be selected. Tubolit DG will degrade if left exposed to sunlight for extended periods.
Wall Thickness Guide — 9mm vs 13mm
| Wall |
Best for |
Notes |
| 9mm |
Cold water services, condensate pipes, loft frost protection, confined spaces |
Economical; easier to fit in tight runs; adequate for cold water and basic frost protection |
| 13mm |
Heating system pipework, hot water services, compliance with Part L |
Standard specification for domestic heating; provides better thermal performance and meets typical building regulation requirements |
Frequently Asked Questions
What is the difference between the 9mm and 13mm wall versions?
The wall thickness determines the amount of insulation around the pipe. The 13mm wall provides greater thermal resistance and is the standard specification for central heating and hot water pipes in domestic installations, where reducing heat loss from the pipework is the primary aim. The 9mm wall is thinner, making it easier to fit in confined spaces such as airing cupboards and around tight corners, and is well-suited to cold water pipes and condensate pipe protection where the objective is primarily condensation prevention or basic frost protection rather than heat retention.
Can Tubolit DG be used outdoors?
Tubolit DG is designed for indoor use and is not UV-stable. It can be used as a short-term or seasonal frost protection measure in exposed locations, but it will degrade over time if permanently exposed to direct sunlight and weathering. For permanent outdoor pipe insulation on heat pump installations or other external applications, a UV-resistant product such as Armaflex Tuffcoat or Primary Pro pipe insulation is the correct choice.
How do I install Tubolit DG on an existing pipe without disconnecting it?
Tubolit DG is supplied as a semi-slit tube, meaning it has a partial slit running the length of the tube that can be fully opened by hand. To fit to an existing pipe, fully open the slit along the length of the section, press it around the pipe, and close the slit. The seam and all butt joints between lengths should be sealed with Armacell insulation tape or a compatible adhesive to ensure continuity of the insulation layer and prevent moisture ingress at joints.
Does Tubolit DG comply with Building Regulations Part L?
Part L of the Building Regulations requires all pipes in a heating system to be insulated to prevent unnecessary heat loss. Tubolit DG 13mm wall, applied to all accessible heating pipework including within airing cupboards, under floors, and in loft spaces, is an accepted method of meeting this requirement in domestic installations. For heat pump external pipework specifically, a UV-stable external-grade insulation is required — Tubolit DG 13mm is suitable for the internal pipework runs associated with an ASHP installation.
Can Tubolit DG be used on plastic and push-fit pipe as well as copper?
Yes. Tubolit DG bore sizes are specified to match the outside diameter of standard copper tube, but the material is flexible enough to accommodate plastic, CPVC, and other pipe types with the same or similar OD. For pushfit or barrier pipe systems where the OD differs slightly from standard copper, select the nearest bore size and confirm the fit before cutting. The flexible foam will accommodate minor tolerance differences.
Related Products:
Primary Pro Heat Pump Pipe Insulation Range (UV-stable, external ASHP use) | Primary Pro AS32 Anti-Freeze Valve Insulation Shell | Intatec ZERO28 Anti-Freeze Valve | Intatec ZEROGUARD Anti-Freeze Valve Protector | Intatec 28mm Zero Heat Pump Installer Pack
