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Best expanding foam UK

Updated: 23 October 2026

You want one can from the seven kept on amazon.co.uk, and a single winner will be the wrong can for half the jobs. The best expanding foam UK, in this set, depends on whether you own a foam gun, whether the hole is one session, and whether anyone has told you the foam must resist fire. Prices and stars are the amazon.co.uk captures from 19 October 2026, held on the [insulating spray comparison](/hub/diy-supplies/insulating-spray). Peter F. read the UK reviews and the Soudal UK gun gap-filler sheet. There is no lab test in these sources. A purchase through our links can earn a commission at no extra cost to you.

You want one can from the seven kept on amazon.co.uk, and a single winner will be the wrong can for half the jobs.

Our top picks

Soudal Soudal Soudafoam Gap Filler

Best overall

Soudal Soudal Soudafoam Gap Filler
9.2/10about £7.19
View offer
Gorilla Filler Gorilla Filler 500 ml

Best value

Gorilla Filler Gorilla Filler 500 ml
8.6/10about £6.75
View offer
Gorilla Gorilla Heavy Duty 353 ml

Alternative

Gorilla Gorilla Heavy Duty 353 ml
8.4/10about £9.93
View offer
On this page
  1. 1.Best straw can for a single gap
  2. 2.Best gun-grade can if you already have a gun
  3. 3.When the dearer cans are the wrong buy
  4. 4.What best must not mean

Best straw can for a single gap

For one ordinary gap today, the straw can with the deepest record is Gorilla Filler, 500 ml, at about £6.75. The listing is 4.3 from 7,701 reviews. The listing says waterproof, and that cured foam can be cut, painted and sanded. Reviewers say upward beads drip, the foam is very sticky, and the straw is one use unless you clear it. Paint Factory is cheaper at about £5.82, but UK texts describe weak expansion and a nozzle that clogged within minutes. If you expect to come back tomorrow, read the gun versus straw page.

Best gun-grade can if you already have a gun

If a foam gun is already on the bench, Soudal Soudafoam Gap Filler is the top pick in this set. It is about £7.19 for 750 ml, 4.6 from 411 reviews, the highest star line here. The listing says full cure in one day, and it names water resistance and heat resistance. The gun is not in the box, and it leaks if you take the gun off and screw it back on. One reviewer said Soudal's window foam was better for frames. Soudal's UK sheet quotes about 28 litres from 750 ml and 0.037 W/m·K. The amazon.co.uk page does not repeat those figures. Bond-It Fill 'n' Fix at about £9.31 is the other gun can, 4.1 from 80 reviews. The buying guide puts its B3 class next to a tested joint, which this can is not.
Soudal Soudal Soudafoam Gap Filler

Testsieger

Soudal Soudal Soudafoam Gap Filler
9.2/10about £7.19
View offer

When the dearer cans are the wrong buy

Gorilla Heavy Duty is the can to open when you need a number on the gap. Model 115953 is about £9.93 for 353 ml, 4.2 from 490 reviews, and the bullets say gaps and cracks up to 2.5 cm, tack-free in 8 to 12 minutes, and trimming in 45 minutes. Outdoor foam on this listing must be painted or coated. It is a poor swap for the 500 ml Gorilla Filler can unless you are using the stated width. Gorilla Weatherproof, two 500 ml stone cans, is about £10.82. The brand field says JKG Unknown. That pack makes sense for two separate sessions. Ferris, two 500 ml cream cans, is about £15.99. The brand field is FERRIS, not Gorilla, and the energy-bill bullet has no figure.

What best must not mean

Best in this set is a match between can and job. It is not a fire-stop award. Hertfordshire Building Control's note still applies: foam fire-stops only the tested joint, often with mineral fibre behind it. These cans are not loft spray foam, and an energy-bill bullet is not a measured saving. If you wheeze or a rash spreads after use, stop and get medical help.

Common questions

Which can has the highest score in this set?
Soudal Soudafoam Gap Filler has the highest score we assigned, from 4.6 and 411 amazon.co.uk reviews at about £7.19. It is gun grade, and the gun is not included. The score is from listing data and UK review themes, not from a lab. A higher score does not make it the right can if you have no gun.
Is the most-reviewed can the one to buy?
Gorilla Filler has the most reviews, 7,701 at 4.3, and it is the straw can to buy for one gap. The count means a lot of people have used a 500 ml nozzle can. It does not mean the can will work next week, and it does not beat Soudal when you already meter foam with a gun. Review depth and the right valve are different questions.
Is the about £15.99 twin pack better because it is two cans?
No. Ferris at about £15.99 is two 500 ml straw cans with nozzle and drip complaints in the UK texts, and the brand field says FERRIS. The Gorilla two-pack is about £10.82 for the same stated volume and a much larger review count. Two cans help only when you have two sessions. For one hole you pay for foam the straw may never let out.
Should I buy Soudal if I do not own a gun?
Not as a first can. The listing is gun grade, included components do not list a gun, and a straw will not fit the valve. You would still need a gun and a cleaner, which are not in this comparison and not in the about £7.19. For one hole without a gun, Gorilla Filler at about £6.75 is the set's best value straw can.
Which can states a fire class, and does that make it the safe pick?
Only Bond-It states one: DIN 4102 Class B3, described on the listing as foam with no fire-resistant additives. That is a flammability class, not a UK fire-stop approval. It does not make BDFIXG750 safer around a door frame than Soudal. For a fire-resisting joint you need a tested system, which is outside this basket.

Related pages

How to use insulating spray

Insulating spray on windows and doors

Insulating spray

Expanding foam buying guide: valve, gap and fire class

Gun foam vs straw foam: valve, reuse, and one hole

Sources

Public UK sources and the amazon.co.uk listings compared on this page. Prices stored 19 October 2026. Updated 22 October 2026.

  1. HSE: Isocyanates (retrieved October 2026)
  2. HSE: Isocyanate spraying (retrieved October 2026)
  3. RICS: Spray foam insulation consumer guide (retrieved October 2026)
  4. Commons Library CBP-10658 (retrieved October 2026)
  5. Hertfordshire Building Control: PU foam (retrieved October 2026)
  6. Soudal UK: Soudafoam Gun Gap Filler TDS (retrieved October 2026)
  7. Polycell: Expanding foam (retrieved October 2026)
  8. Soudal UK: Filling gaps and holes (retrieved October 2026)