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Best insulation boards

Updated: 23 October 2026

You want one board for a small job, or a clear reason to buy none of them. Best insulation boards, in this amazon.co.uk set, means the sheet that matches the job you named, not the row with the most stars. The five kept listings are a 50 mm EPS pack, a 10 mm EPS pack, a 10 mm XPS underlay, and two foam tile backers. Full-size foil PIR is not a row here. The [insulation slab comparison](/hub/diy-supplies/insulation-slab) holds the table. Figures are from 21 October 2026. These boards were not tested in a lab. A purchase through our links can earn a commission at no extra cost to you.

You want one board for a small job, or a clear reason to buy none of them. Best insulation boards, in this amazon.co.uk set, means the sheet that matches the job you named, not the row with the most stars.

Our top picks

Triplast Triplast EPS 70 50 mm six-pack

Best overall

Triplast Triplast EPS 70 50 mm six-pack
7.4/10about £47.59
View offer
Thermopanel Thermopanel 15 mm tile backer

Best value

Thermopanel Thermopanel 15 mm tile backer
7.2/10about £15.99
View offer
Thermopanel Thermopanel 40 mm tile backer

Alternative

Thermopanel Thermopanel 40 mm tile backer
7.2/10about £20.89
View offer
On this page
  1. 1.Best in this set for a small outbuilding lining
  2. 2.Best when the job is a wet-room backer
  3. 3.Skip the 10 mm packs for a real build-up
  4. 4.When none of the five is the board

Best in this set for a small outbuilding lining

The top pick for a small shed, summerhouse, or workshop lining is the Triplast EPS 70 six-pack: six sheets, 1200 × 600 × 50 mm, at about £47.59. The line is 4.6 from 345. That star line is shared with the 10 mm pack. Lambda is a range, 0.030–0.038 W/mK, and fixings are not in the box. The coverage field prints 7.75 square feet, while six sheets at the stated size are 4.32 m². Skip the pack for a U-value floor, a wall that might sit over 11 m, or a job that needs one declared lambda. Those checks are the buying guide.

Best when the job is a wet-room backer

The best value of the two boards that print 0.027 W/mK is the Thermopanel 15 mm board, part TP15, at about £15.99: one sheet, 1250 × 600 mm, 0.75 m². The 40 mm board is about £20.89, with the same lambda and the same 4.5 from 349 reviews. Reviewers tape, seal, and tile. Adhesive, washers, screws, tape, and the heating mat are not in the box. The material field only says Foam, and no tanking standard is named. Take 15 mm when that depth is enough, and 40 mm when the build-up needs it. Leave both for a floor U-value. The £7.99 EkoBoard is the lowest price, and it has no lambda, so it is not the best value.
Triplast Triplast EPS 70 50 mm six-pack

Testsieger

Triplast Triplast EPS 70 50 mm six-pack
7.4/10about £47.59
View offer

Skip the 10 mm packs for a real build-up

The Triplast 10 mm ten-pack is ten sheets of 600 × 400 mm at about £16.89, sold for insulation, packaging, and craft. The shared 4.6 from 345 covers that mix. Ten sheets are 2.4 m², while the coverage field prints 2.58 square feet. It can patch a lining. It is not a ground floor. The floor page sets out that limit. EkoBoard is one XPS board, 1200 × 600 × 10 mm, at about £7.99, with 4.2 from 123 reviews. Many are model-making, and more than one reports breakage. There is no lambda and no BS EN 13164 number. A bill-saving bullet has no figure. A warmer room under laminate is a comfort comment, not a U-value.

When none of the five is the board

On 21 October 2026 amazon.co.uk showed 2400 × 1200 × 50 mm PIR packs from about £144 for four sheets to £419.99 for twelve. Those packs were not opened here. A shed guide that asks for 25–50 mm PIR is talking about that foil board, not the small Triplast ten-pack. None of these five is the board for a tall residential external wall: no Euroclass is printed. A floor that must hit a U-value, and electric underfloor heating as a system, need a calculation the box does not supply. Among the five, use the 50 mm pack for a small outbuilding, the 15 mm backer when that depth is enough for tiles, and neither 10 mm pack when someone will ask for a U-value.

Common questions

Which of these boards is the one for a shed wall?
In this set, the Triplast 50 mm six-pack at about £47.59. It is the only wall-and-floor sheet with 50 mm of EPS, and United Kingdom reviews describe outbuildings. The lambda is a range, 0.030–0.038 W/mK, the review text is shared with the 10 mm pack, and cutting is messy. Skip it if you needed a declared 0.022 W/mK foil PIR sheet.
Which board is for a shower or a wet-room wall?
The Thermopanel boards are the wet-room rows. The 15 mm board at about £15.99 is the best value of the two that print 0.027 W/mK. The 40 mm board is about £20.89 if you need the thickness. Reviewers tape, seal, and tile. You still buy adhesive, washers, and screws, and the listing names no tanking standard.
Is the £7.99 EkoBoard the best value?
No. It is the cheapest board in the set, and the listing has no lambda, so the price cannot be checked against a thermal result. The best value here is the 15 mm Thermopanel at about £15.99, because it prints 0.027 W/mK and costs less than the 40 mm board with the same figure and the same reviews. EkoBoard’s 4.2 from 123 includes a lot of model-making.
Should I buy the 10 mm Triplast pack as floor insulation?
No, not as the insulation that a ground floor is judged on. Ten sheets of 600 × 400 × 10 mm at about £16.89 are a thin EPS pack also sold for packaging and craft. The stars, 4.6 from 345, are shared with the 50 mm pack. A 10 mm sheet does not become a floor specification because the parent title says insulation.
Do I need a heating mat as well as the Thermopanel board?
Yes, if the job is electric underfloor heating. Neither Thermopanel listing includes the mat, the adhesive, or the washers. The bullet says the board is for wet areas with electric underfloor heating. That is a claimed use, not a kit. The same gap sits on the EkoBoard underlay.
Where do I buy a full-size foil PIR sheet if none of these is that product?
Not from these five rows. On 21 October 2026 amazon.co.uk showed 2400 × 1200 × 50 mm foil packs from about £144 for four sheets to £419.99 for twelve. We did not test those packs. Use them only when the depth is tight, the fire class on that product’s own sheet allows it, and you are not fitting foam to a tall external wall.

Related pages

How to fit insulation boards

Insulation slab

Insulation board buying guide: nation, then lambda

Insulation boards for floors: why 10 mm is not 0.18

PIR vs EPS insulation boards: thinner, then fire class

Sources

Public UK sources and the amazon.co.uk listings compared on this page. Prices are the amazon.co.uk figures stored on 21 October 2026. Updated 22.10.2026.

  1. Approved Document L 2026, GOV.UK (retrieved 22.10.2026)
  2. Scottish building standards handbook 2022, section 6.2 (retrieved 22.10.2026)
  3. Ban on combustible materials, GOV.UK (retrieved 22.10.2026)
  4. Circular letter 02/2022, combustible materials (retrieved 22.10.2026)
  5. Recticel Eurothane GP datasheet (retrieved 22.10.2026)
  6. Polyfoam XPS: ground floor insulation (retrieved 22.10.2026)
  7. IMA: PIR floor insulation guidelines, November 2024 (retrieved 22.10.2026)
  8. HSE cellular plastics, HSG92 (retrieved 22.10.2026)