Best Pipe Insulation UK 2026: Lagging That Actually Fits

The Short Answer

Wrap any hot water or heating pipes that run through unheated spaces — lofts, garages, under suspended floors — with foam pipe lagging. Most UK homes need 22mm (for heating pipes) and 15mm (for hot water runs). A 10-pack of 2-metre tubes costs £10–£20 and takes about 30 minutes to fit. It's one of those jobs that's so cheap and easy there's genuinely no excuse not to do it.

Why It Matters

An uninsulated hot water pipe running through your loft in January is losing heat to the cold air around it — heat you've paid for. The longer the pipe run, the more heat you lose. In a typical house with 10–15 metres of exposed pipework in the loft and garage, uninsulated pipes can waste £30–£60 per year in heat that never reaches a radiator or tap.

It also matters for frost protection. If pipes in your loft or garage freeze in winter, they can burst — and the damage from a burst pipe is catastrophic (we're talking thousands in repairs, ruined ceilings, insurance claims). Pipe insulation won't prevent freezing in an extreme cold snap, but it buys you critical extra hours of protection.

If you have a heat pump, pipe insulation matters even more. Heat pumps run at lower flow temperatures than gas boilers, so the water in the pipes is cooler to begin with. Every degree lost through uninsulated pipes is a bigger proportional waste.

What Size Do You Need?

Pipe insulation comes in sizes that match the outer diameter of the pipe it fits over. UK homes almost always use copper pipes in two sizes:

• 15mm — used for most hot water runs and smaller heating circuits. This is the thinner pipe.
• 22mm — used for main heating flow and return pipes, and hot water pipes from the cylinder. This is the thicker pipe.

If you're not sure, measure the outside diameter of the pipe with a tape measure. 15mm pipe measures about 15mm across; 22mm pipe measures about 22mm. It's not rocket science.

For most homes, you'll want both sizes. Buy more than you think you need — the leftover tubes will sit in the loft for 20 years without degrading.

What to Buy

For Standard Pipe Runs: Climaflex Foam Tubes

Climaflex is the standard choice and what you'll find in most builders' merchants. The tubes are pre-slit down one side so you can snap them over existing pipes without disconnecting anything. They're flexible enough to go around gentle bends and they stay in place without adhesive in most cases (though a wrap of tape at each end doesn't hurt).

A 10-pack of 2-metre tubes costs £10–£20 depending on the diameter. For a typical semi with exposed pipes in the loft and garage, 2–3 packs should cover everything.

For Bends and Joints: Pipe Insulation Tape

Straight pipe runs are easy. The tricky bits are the bends, T-joints, and valve connections where standard tubes don't fit neatly. Self-adhesive foam tape is the solution — you wrap it around the awkward sections to close the gaps. A 10-metre roll costs £4–£8 and covers all the fiddly bits in a typical loft.

This is the step most people skip, and it's a mistake. Uninsulated bends and joints are where heat escapes most — it's like wearing a coat with no sleeves.

Where to Insulate

Focus on pipes in unheated spaces:

• Loft — any visible pipes running across the loft floor or up to tanks
• Garage — especially if the garage shares a wall with the house
• Under suspended timber floors — if you can access the void underneath
• Outside runs — any short sections of pipe that run along external walls or through unheated utility rooms

You don't need to insulate pipes inside heated rooms — they're already contributing warmth to the room, so insulating them would actually be counterproductive.

How to Fit It

1. Measure your pipe runs — walk around the loft and garage and note how many metres of 15mm and 22mm pipe you can see
2. Open the slit and snap over the pipe — the tube is pre-slit so you just open it up and push it onto the pipe. No tools needed.
3. Tape the seam — a strip of duct tape or insulation tape along the slit keeps it closed
4. Wrap the bends — use foam tape on any 90° bends, T-pieces, or valves where tubes can't reach
5. Secure at intervals — a cable tie or tape every metre or so stops tubes sliding off over time

The whole job takes 20–40 minutes for a typical loft. You'll spend more time getting into the loft than doing the actual work.

Cost and Savings

Item	Cost
Climaflex 22mm x 2m (10-pack)	£12–£20
Climaflex 15mm x 2m (10-pack)	£10–£18
Foam insulation tape (10m)	£4–£8
Total	£26–£46

Annual saving: £30–£60. Payback: well under a year. Plus the frost protection, which is priceless if it saves you from a burst pipe.

For more low-cost insulation wins, see our draught-proofing guide and loft insulation guide. For the full picture on making your home more efficient, read our energy efficiency guide.