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Radiator reflector foil

Updated: 23 October 2026

Radiator reflector foil is worth buying when the radiator sits on an uninsulated external wall and you want a purpose-made sheet in the gap, not a new wall. It is a weak buy on an internal wall, and the wrong buy if a roll is meant to stand in for insulation panels on the house. The pound saving is not a measurement of the rolls in our [insulation panels comparison](/hub/diy-supplies/insulation-panels). Peter F. used the amazon.co.uk listings, United Kingdom reviews and the Energy Saving Trust’s pages on 21 October 2026. We did not meter a room. A qualifying purchase can earn a commission at no extra cost to you.

Radiator reflector foil is worth buying when the radiator sits on an uninsulated external wall and you want a purpose-made sheet in the gap, not a new wall.

Our top picks

Fabian Clarke London Fabian Clarke 10 m radiator foil

Best overall

Fabian Clarke London Fabian Clarke 10 m radiator foil
7.4/10about £17.99
View offer
Fabian Clarke London Fabian Clarke 5 m radiator foil

Best value

Fabian Clarke London Fabian Clarke 5 m radiator foil
7.2/10about £14.99
View offer
wordmouk wordmouk 5 m bubble foil

Alternative

wordmouk wordmouk 5 m bubble foil
6.8/10about £10.98
View offer
On this page
  1. 1.When reflector foil is worth it
  2. 2.Four rolls and what you actually get
  3. 3.Thickness and tape
  4. 4.What foil will not do

When reflector foil is worth it

The Energy Saving Trust says a purpose-made reflector is most effective behind radiators on uninsulated external walls. Heat that passes into an internal wall still ends up in the house, so those walls are not really worth it. Kitchen foil tears. The Trust tells you not to use it. Follow the Trust, not a tip that ordinary kitchen foil can help. If you have not separated foil from a board or a tile, use the insulation panels buying guide. Turn the heating off before you fit anything. An Energy Performance Certificate is a clue if you do not know whether the wall is insulated. If the wall is internal, or already insulated, stop.

Four rolls and what you actually get

The 5 m Fabian Clarke roll is £14.99, a stated 3 m², 4.5 from 2,196 reviews, country of origin the United Kingdom. It is the best value pick for a few radiators. The 10 m roll is £17.99 for a stated 6 m² and 4.6 from 380 reviews. The best insulation panels page puts the short roll first. wordmouk is £10.98 and 4.5 from 285 reviews. Reviews also use it on pipes and a summerhouse roof. JMIATRY is £23.99, only 0.32 m wide, and the 95% line is the seller’s sentence. None of these rolls prints a lambda.
Fabian Clarke London Fabian Clarke 10 m radiator foil

Testsieger

Fabian Clarke London Fabian Clarke 10 m radiator foil
7.4/10about £17.99
View offer

Thickness and tape

Fabian Clarke says 4 mm. One United Kingdom review says the bubbles are about 2 mm. Another buyer returned a roll as too thick for a tight gap. Measure the clear gap with the radiator cold. If 4 mm will not slide, a 7 mm JMIATRY roll is a worse bet, not a better one. On the 10 m roll, several reviews say the strips ran out. wordmouk’s tape came off after three days in one review, and another buyer says you must press hard. JMIATRY is self-adhesive, and two of six United Kingdom reviews say the liner takes the adhesive or the glue fails when hot. Included components on that listing are marked as none. The fitting order, shiny side towards the room, is on the how to fit insulation panels page. A roll that will not stick, or will not fit the gap, is not a bargain at £10.98.

What foil will not do

Foil will not deliver the U-values in Approved Document L. In England, Table 4.2 limits new fabric in an existing dwelling to 0.15 W/(m²·K) for a roof and 0.18 for a wall or a floor. A bubble sheet with no lambda cannot be shown to meet that. Insulating the wall is a different product from a merchant, not a second layer of radiator foil. A warmer feeling is what many reviewers report, and a minority report no change. Feeling is not a measured bill. We will not average the Trust’s estimate with a blog that says £6 or £10–£25 and call the result your saving. Foil will not fix echo, neighbour noise or a ringing car panel. On an internal wall, or on an external wall that is already insulated, the reflector has less work to do.

Common questions

Does radiator foil work?
It can, on an uninsulated external wall, as a purpose-made reflector rather than kitchen foil. United Kingdom reviews of the Fabian Clarke rolls often say the wall feels warmer, and a minority notice nothing. That is a felt change, not a measured cut in the bill.
Should I fit it on internal walls?
The Energy Saving Trust’s view is that internal walls are not really worth it, because heat lost into an internal wall is still inside the dwelling. A cold patch on an outside wall is the situation these rolls are for. Check the plan, or an Energy Performance Certificate, before you buy several rolls.
Is kitchen foil good enough?
No. The Energy Saving Trust says kitchen foil is the wrong product. It tears at the brackets and is not made to stay on plaster for a heating season. A cheaper roll in this set is still a purpose-made reflector, not cooking foil.
Will I save £18 a year with these rolls?
Do not read it as a test of these rolls. The Energy Saving Trust estimates about £18 a year in Great Britain, and about £20 in Northern Ireland, for radiator reflectors as a measure, with an install cost around £25. Your bill depends on the wall and how much of the radiator you cover.
How much roll do I need?
Measure the wall you can reach, not the radiator’s catalogue size. The 5 m Fabian Clarke roll is a stated 3 m². The 10 m roll is a stated 6 m². JMIATRY is about 3.2 m² but only 0.32 m wide, so a wide radiator needs joins. Buy extra tabs with the 10 m roll.
What if the foil is too thick for the gap?
Leave it out. A stated 4 mm Fabian Clarke roll was too thick for one buyer, and another review says the bubbles are nearer 2 mm. JMIATRY is stated at 7 mm. Measure the cold gap. Forcing the sheet creases it and pulls the tabs off.
Is foil a substitute for insulating the wall?
No. A reflector changes heat that has already reached the back of the radiator. It does not give the wall the U-value in Approved Document L, and none of these rolls publishes a lambda. If the whole wall is cold, the wall itself is a different specification.

Related pages

Insulation panels

Acoustic foam vs soundproofing, and when heat is the job

Best insulation panels for the job you actually have

Insulation panels: which listing you should ignore

How to fit insulation panels without the usual failures

Sources

Public UK sources and the amazon.co.uk listings compared on this page. Shelf prices are the stored capture, not a live check on 21 October 2026. Updated 23 October 2026.

  1. Approved Document L Volume 1, Table 4.2 (retrieved 21 October 2026)
  2. Energy Saving Trust, radiator reflector panels (retrieved 21 October 2026)
  3. Energy Saving Trust, quick DIY jobs (retrieved 21 October 2026)
  4. Energy Saving Trust, product standards (retrieved 21 October 2026)
  5. BEWI Jabfloor datasheet (retrieved 21 October 2026)
  6. Ikoustic, sound-reducing foam (retrieved 21 October 2026)
  7. Resonics, which acoustic foam (retrieved 21 October 2026)
  8. Veedub Hub, campervan insulation (retrieved 21 October 2026)