Pipe lagging buying guide
Updated: 23 October 2026
You are in the loft with a tape measure on bare copper, and the basket is already tempting you with a 2 metre tube, a 10 metre pack, a silver roll, and a blue sleeve whose title looks long. This pipe lagging buying guide is the order to follow before you pay: the pipe’s outside diameter, then the wall, then the length, then how the seam closes. Stars come after those four. The [pipe insulation comparison](/hub/diy-supplies/pipe-insulation) holds the eleven amazon.co.uk listings, the prices in GBP, and the review counts saved on 21 October 2026. Those listings and public UK sources were read for this page. We did not run a hot-box test, and a printed lambda is not a Building Regulations pass. A purchase can earn a commission at no extra cost to you.
You are in the loft with a tape measure on bare copper, and the basket is already tempting you with a 2 metre tube, a 10 metre pack, a silver roll, and a blue sleeve whose title looks long.
You are in the loft with a tape measure on bare copper, and the basket is already tempting you with a 2 metre tube, a 10 metre pack, a silver roll, and a blue sleeve whose title looks long. This pipe lagging buying guide is the order to follow before you pay: the pipe’s outside diameter, then the wall, then the length, then how the seam closes. Stars come after those four. The pipe insulation comparison holds the eleven amazon.co.uk listings, the prices in GBP, and the review counts saved on 21 October 2026. Those listings and public UK sources were read for this page. We did not run a hot-box test, and a printed lambda is not a Building Regulations pass. A purchase can earn a commission at no extra cost to you.
Our top picks
| Badge | Product | Pipe size | Wall | Closure | Note | Price | Offer |
|---|---|---|---|---|---|---|---|
| Best overall |  Climaflex Climaflex 22 mm, 13 mm wall, 10 m | 22 mm | 13 mm | Slit only | 7.6 | about £11.05 | View offer |
| Alternative |  LavaTherm LavaTherm 28 mm self-seal, 2 m | 28 mm | 9 mm | Self-seal | 7.2 | about £13.75 | View offer |
 K-FLEX K-Flex 15 mm self-seal, 2 m | 15 mm bore | 9 mm title | Self-seal | 7.4 | about £8.99 | View offer |
On this page
Measure the pipe, not the title
UK copper in the shops is sold as 15 mm, 22 mm, or 28 mm, and those numbers are the outside of the pipe. B&Q’s guide to insulating water pipes works in those three sizes, and Travis Perkins asks you to match the bore of the foam to that outside diameter before you worry about thickness or tape. The hole in the lagging has to slide over the copper you can see. It is not the hole inside the pipe, and it is not a guess from a title written in inches.
A 15 mm tube will not go onto 22 mm copper, and a loose hole on a smaller pipe leaves a slit of air. In this comparison the titles that match the trade sizes are the K-Flex 15 mm bore, the Climaflex pack sold for 22 mm pipe, and the LavaTherm tube sold as 28 mm. Dshunnc and Nadinsta state a 16 mm internal diameter. Both METERXITY pieces state 25 mm inside. None of those four titles says 15, 22, or 28 mm copper. One UK review of the 1.8 m METERXITY tube said the hole was larger than expected. Measure the outside, and if the pipe is plastic or an older imperial size, measure that outside too.
Wall thickness is not a pass mark
Nine millimetres and 13 mm are both on sale, and they do different amounts of work. Wickes shelves 15 × 13 mm and 22 × 13 mm tubes, so a UK merchant treats 13 mm as a normal domestic wall. In this set Climaflex is the 13 mm wall, on 22 mm pipe, ten 1 m lengths at about £11.05. K-Flex and LavaTherm are 9 mm walls, 2 m each, at about £8.99 and about £13.75. A thicker closed-cell wall slows heat more than a thinner one of the same material. That sentence is not a certificate.
Approved Document L in England, the 2021 edition with 2023 amendments, points heating and hot-water pipes outside the heated space towards insulation whose heat loss stays within BS 5422. Table 4.4 gives thicknesses, including 10 mm on pipes up to 25 mm nominal internal diameter, only when the material is 0.025 W/(m·K) or better. K-Flex is the only kept listing that prints a lambda table, about 0.033 at 0 °C and 0.035 at 20 °C. That is not the Table 4.4 case. A 9 mm wall is not a pass because of that gap. Climaflex prints no lambda on this listing. Figures quoted on other retailers’ pages stay on those pages. Scotland, Wales, and Northern Ireland cite BS 5422 in their own books.
Length, slit, and tape
Count the exposed run in metres, then add for the cuts a bend will waste. Two 3 m drops of 22 mm pipe are already 6 m before you mitre an elbow. One 2 m tube is a third of that job. The Climaflex pack is 10 × 1 m, so you can cut a length to a drop, and at about £11.05 it is about £1.11 a metre. Thames Water said in December 2025 that typical internal lagging usually costs around £1 a metre. That is their figure for a typical job, not a promise that this pack is the cheapest in a merchant’s yard.
K-Flex and LavaTherm claim a self-seal strip. Climaflex is slit only, with no adhesive in the listing, and one reviewer said to put that split at the bottom. UK reviews of the K-Flex strip disagree: some peel it and close the seam, others say the tape was missing or would not stay stuck. If you do not trust the strip, budget for tape. The blue METERXITY sleeve is 430 mm long in the size bullet, at about £9.49, and the title is easy to read as metres. The XZSKD title says a 5 m roll of 5 mm foam, and the item dimensions say 10 cm by 10 cm. A foil roll is a different shape, which is foam pipe lagging or foil wrap.
What this guide will not choose
This page stops at the order of decisions. It does not name a top pick. Once you know you need 15 mm, 22 mm, or 28 mm, and whether you want a printed lambda or simply more metres of 13 mm wall, the best pipe insulation page applies those criteria to the listings. Fitting, including which way a slit can face, is how to lag pipes.
Leave the basket if the only match is a 16 mm or 25 mm hole and your copper is a trade size, if the title and the dimensions describe two different lengths, or if you needed a fire class and the listing prints none. A 5 mm tape and a 3.8 mm foil wrap can still be the right thing for an elbow after the tube is chosen. They are not the first line you buy for a straight loft run.
Common questions
Is 15 mm lagging for 15 mm copper, or for the hole inside the copper?
It is for the outside of 15 mm copper. UK shops sell 15 mm, 22 mm, and 28 mm as the outside diameter, and the foam’s hole has to pass over that pipe. The bore of the copper, the hole the water runs through, is a smaller number. Ordering from the inside measurement gives you a tube that will not go on.
Do I need a 9 mm or a 13 mm wall?
You need the wall you can justify, not a single compulsory number. A 13 mm closed-cell wall, such as the Climaflex pack in this set, is the thicker domestic option here. A 9 mm wall, on the K-Flex and LavaTherm tubes, is thinner. Thicker foam of the same type slows heat more. Neither thickness, on its own, is a Building Regulations pass.
Does 9 mm meet Building Regulations?
Not as a claim this page will make. Table 4.4 in Approved Document L applies only when lambda is 0.025 W/(m·K) or better, and the only printed lambda in this set is about 0.033 at 0 °C on the K-Flex tube. That table therefore does not apply to it. We have not calculated a BS 5422 thickness, and 9 mm is not labelled illegal here either.
Should I buy self-seal lagging or a plain slit?
Buy the strip if you want the seam to close without a separate roll of tape, and still keep tape in the toolbox. K-Flex and LavaTherm claim a strip, and K-Flex reviews say that strip sometimes fails. Climaflex is a plain slit. A slit that stays open is an air gap, whether or not the listing used the words self-seal.
How many metres should I buy?
Measure the exposed pipe, then add for mitres at bends and for a short piece over a stopcock if you are covering that too. A single 2 m tube does not cover two 3 m drops. The 10 m Climaflex pack is ten 1 m lengths, which you cut. The 430 mm METERXITY sleeve is not a metre, whatever the title suggests.
Why does one listing say 16 mm or 25 mm?
Because that is the hole the seller printed, and it is not one of the three trade sizes B&Q and Travis Perkins use for copper. Dshunnc and Nadinsta are 16 mm inside. The METERXITY tubes are 25 mm inside. Use them when you have measured a pipe that matches that hole. Do not assume a 16 mm hole is 15 mm copper, because the listing does not say so.
What if the title looks like 2.4 metres?
Read the size bullet before the title. On the short METERXITY sleeve the bullet says 430 mm long. Buyers who trusted the title expected a run and received a pad, at about £9.49. On the XZSKD listing the title says 5 m and the dimensions say 10 cm by 10 cm. If those two lines do not agree, do not plan the loft around either of them.
Related pages
Sources
Public UK sources and the amazon.co.uk listings compared on this page. Listings captured 21 October 2026. Updated 23 October 2026.
- Approved Document L, Volume 1 (2021, 2023 amendments) (retrieved 23 October 2026)
- BSI, BS 5422:2023 (retrieved 23 October 2026)
- Rockwool guide to BS 5422:2023 (retrieved 23 October 2026)
- Energy Saving Trust: insulating tanks and radiators (retrieved 23 October 2026)
- Thames Water winter tips, December 2025 (retrieved 23 October 2026)
- WaterSafe winter advice (retrieved 23 October 2026)
- HHIC condensate guide (retrieved 23 October 2026)
- B&Q: how to insulate water pipes (retrieved 23 October 2026)