Best pipe insulation UK: foam lagging and foil wrap compared

Choose pipe insulation by pipe outside diameter, insulation wall thickness and location. A 15mm sleeve describes the hole for a 15mm pipe; it does not tell you how thick the insulation is. For winter protection, the thicker wall is usually the more important comparison once the bore fits.

This buying guide is deliberately distinct from how to fit pipe lagging, which covers bends, joints, loft cisterns and safe access. We have not tested these products.

Shortlist by job

Product or format	Published construction	Size or performance point	Best fit to investigate
Wickes Economy foam tube	Pre-slit polyethylene	15mm pipe, 13mm wall, 2m length	Accessible straight indoor runs where the published wall suits the risk
Wickes Byelaw-size foam tube	Thicker polyethylene tube	15mm pipe, 25mm wall in the current range listing	Colder loft or outbuilding runs where a thicker wall fits the space
Armacell Tubolit S	Closed-cell polyethylene foam to EN 14313	Declared conductivity no more than 0.040 W/(m·K) at 40°C	A specification-led heating or plumbing installation
ThermaWrap spiral foil wrap	Foil-faced bubble wrap	50mm × 7.5m	Awkward bends and shapes where a rigid tube is difficult to close neatly

Embed this infographic

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  <a href="https://leatmere.co.uk/guides/best-pipe-insulation-uk/"><img src="https://leatmere.co.uk/assets/images/best-pipe-insulation-uk-infographic.webp" alt="Comparison infographic showing construction, published size or performance and intended job for four pipe insulation formats"></a>
  <figcaption>Infographic: Best pipe insulation UK from <a href="https://leatmere.co.uk/guides/best-pipe-insulation-uk/">Leatmere</a>.</figcaption>
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AI-generated explanatory illustration; the materials are generic and the image is not a tested installation.

Wickes Economy 15 × 13mm: simple pre-slit foam

We haven't tested this. Figures are as the maker states them (checked 13 November 2026).

The Wickes Economy pipe insulation is listed for 15mm pipe with a 13mm wall and a 2m length. Wickes describes polyethylene that is pre-slit, non-absorbent, rot-proof and intended to reduce heat loss and help prevent freezing.

This is the straightforward format for an indoor straight run. Butt pieces together without gaps and close the slit. The product can only slow heat loss; it cannot guarantee a pipe will never freeze.

Thicker-wall foam: when space and cold exposure allow

Wickes's current pipe insulation and lagging range includes a 15 × 25 × 1000mm “Byelaw” tube. Read that naming as a product description, not proof that one thickness is automatically compliant in every location.

A 25mm wall creates a much larger outside diameter than 13mm foam. Check joist gaps, clips, valve access and neighbouring pipes before buying. The thermal requirement depends on exposure and the applicable rules.

Armacell Tubolit S: for published thermal data

Armacell's Tubolit S technical page describes closed-cell polyethylene foam made to EN 14313. It publishes declared thermal conductivity of no more than 0.040 W/(m·K) at a mean temperature of 40°C, with a 100°C maximum operating temperature for the tube range.

Those data make it easier to specify than an unlabelled foam sleeve. Match the exact tube bore and wall thickness from the current data sheet; do not transfer a figure from one thickness or product family to another.

ThermaWrap foil spiral: for awkward shapes

The ThermaWrap spiral foil wrap at Wickes is a 50mm-wide, 7.5m foil-faced wrap. It is useful around bends, closely spaced pipes and fittings where a foam tube leaves gaps.

Spiral wrap depends on consistent overlap. For a long, straight run, a correctly sized foam tube is faster to inspect and less dependent on the installer's overlap. Around a bend, combining tube insulation with neatly closed joints may be better than leaving bare copper.

Where insulation is not enough

• Fix leaks before covering the pipe.
• Seal severe draught paths where appropriate; moving cold air increases heat loss.
• Keep stopcocks and isolation valves operable.
• Do not wrap a boiler, flue, gas pipe or electrical equipment.
• Do not use ordinary water-pipe foam as a substitute for the boiler maker's specified condensate protection; see condensate pipe freezing.
• If a loft is not safely boarded and lit, use a professional.

For the outside tap itself, compare frost-resistant layouts in frost-free outdoor taps. If a pipe is already frozen, follow the frozen pipe guide rather than applying insulation over it.

Is 25mm wall insulation always better than 13mm?

It generally slows heat loss more, but it must fit, suit the service temperature and be installed without gaps. Compare the exact maker's thermal data and the risk at that location.

Can pipe lagging prevent freezing completely?

No. It delays cooling. A long cold spell can still freeze an isolated pipe, especially in a draughty unheated space.

Should hot-water pipes be insulated too?

Yes, particularly through unheated spaces. Insulation reduces heat lost before the water reaches the tap, but keep it clear of equipment and locations excluded by the maker.