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Liquid rubber for a roof and gutter

Updated: 23 October 2026

The stain on the shed ceiling showed up after a wet week, and the gutter joint over the side door has been dripping onto the path. Liquid rubber for a roof and gutter looks like one tin for both. It is not. A coating can cover sound felt that already sheds water. It does not build a fall, and it does not belong on every plastic. This page is the yes, the different product, or the roofer, before you buy. The scored tins are on the [liquid rubber comparison](/hub/fillers-adhesives-and-sprays/liquid-rubber). A qualifying purchase through our links can earn us a commission at no extra cost to you.

The stain on the shed ceiling showed up after a wet week, and the gutter joint over the side door has been dripping onto the path. Liquid rubber for a roof and gutter looks like one tin for both. It is not.

Our top picks

Gorilla Gorilla Waterproof Coat & Seal, black, 473 ml

Best overall

Gorilla Gorilla Waterproof Coat & Seal, black, 473 ml
9.0/10about £19.30
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Gorilla Gorilla Waterproof Coat & Seal, black, 946 ml

Rank 2

Gorilla Gorilla Waterproof Coat & Seal, black, 946 ml
9.0/10about £30.20
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Tapel Tapel liquid rubber roof coating, white, 1 L

Rank 3

Tapel Tapel liquid rubber roof coating, white, 1 L
8.0/10about £19.99
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On this page
  1. 1.A sound felt roof that already drains
  2. 2.Ponding and the 1:80 fall
  3. 3.Gutters are not one material
  4. 4.Where the sheet says no

A sound felt roof that already drains

A yes looks like weathered felt, asphalt, GRP, concrete or a suitable metal, clean and dry, with water leaving after rain. Skyguard lists sheds, garages and caravans for those substrates at about 1 litre per square metre, so about 5 m² wants about 5 litres. Resincoat’s page draws the same outline and steps back from freshly laid bitumen. Gorilla is the wrong tin for that area. It is a gap coating to 6 mm, and the 946 ml listing says it is not designed to coat large areas. “Up to 10 years” on Skyguard is the maker’s figure only at that rate. It is not a sticker you can move onto a 473 ml tin.

Ponding and the 1:80 fall

If a puddle is still there an hour after rain, a coating will not empty it. BS 6229:2025, as Bauder explains it, expects a finished fall of about 1:80 on most flat roofs. Backfalls are not acceptable. A design fall of 1:60 is a common start, so deflection still leaves 1:80. Zero fall needs a system designed for it. A tin is not that design. Over 4 m, 1:80 drops about 50 mm towards the outlet, and you do not paint that slope on. Skyguard says the coating is not suitable where water ponds. Call a roofer if the puddle stays, the deck feels soft, or the leak is a flashing.
Gorilla Gorilla Waterproof Coat & Seal, black, 473 ml

Testsieger

Gorilla Gorilla Waterproof Coat & Seal, black, 473 ml
9.0/10about £19.30
View offer

Gutters are not one material

Skyguard lists gutters and then bars plastic gutters. Gorilla names gutters and uPVC for a local repair inside 6 mm, and still refuses a large area, a flashing and a pipe under pressure. One uPVC joint under 6 mm, with the rest falling to the outlet, is the 473 ml or 946 ml tin. A whole run is not. Bostik Waterstop allows most plastics and excludes polyethylene, polypropylene and bitumen coatings, in two coats of at least 1.5 mm. It is not in this set. If the plastic is unnamed, or water sits in a belly, you need a new length or a roofer.

Where the sheet says no

Skyguard also bars new lead, new bitumen, damp or frozen surfaces, tanking, fish ponds, balconies, walkways and indoor use. A pond, a balcony and a shower wall are not shed roofs. Flashing is on Gorilla’s no list as well. A weeping joint is not a pipe under mains pressure, and a cut mains sheath is an electrician’s job. A 1:1 mould kit will not waterproof this roof. Why that silicone stays tacky is on liquid rubber vs silicone.

Common questions

Can liquid rubber waterproof a sound felt shed or garage roof?
Yes, when the felt or asphalt is weathered, clean and dry, the water leaves the roof, and you size a trade coating at about 1 litre per square metre. GRP, concrete and suitable metal sit on the same Skyguard list. About 5 m² wants about 5 litres. Gorilla’s tins are for gaps up to 6 mm, not that whole deck.
Will a coating fix a roof that holds puddles?
No. Skyguard says it is not suitable where water ponds. A coating cannot create the finished fall BS 6229:2025 describes, about 1:80 after the roof has deflected. If a puddle is still there an hour after rain, call a roofer.
What does a 1:80 fall mean on a small shed?
It is a finished slope of 1 in 80, not a design ratio you paint on. Over 4 m that is about 50 mm of drop towards the outlet. Bauder treats 1:60 as a common design start so the finished roof can still meet 1:80. Backfalls are not acceptable. Zero fall needs a system designed for it.
Can I coat a plastic gutter with the same tin as the felt?
Not by default. Skyguard bars plastic gutters even though gutters appear in its uses. Gorilla names uPVC for a local repair inside 6 mm and bars a large area. Bostik Waterstop allows most plastics and excludes polyethylene, polypropylene and bitumen coatings. Name the plastic before you buy.
Is a gutter joint a 6 mm job or a 5 litre job?
One joint inside 6 mm, including uPVC named on the Gorilla listing, is the gap coating: 473 ml, or 946 ml if you have several local patches. A 5 litre roof tin is for about 5 m² of sound roof at 1 litre per square metre. A long plastic run with a belly is neither.
When do I call a roofer instead of buying a tin?
When water ponds, the deck is soft, or the failed detail is a flashing. Also when the gutter plastic is on the sheet’s ban list and the leak is more than a 6 mm joint. A coating hides those faults for a week and then leaks at the edge of the new film.

Related pages

How to apply liquid rubber

Liquid rubber buying guide

Best liquid rubber

Liquid rubber

Liquid rubber vs silicone for roofs, gaps and moulds

Sources

Public UK sources used for this comparison. amazon.co.uk prices, stars and review counts were taken from the listings on 19 October 2026.

  1. Skyguard liquid rubber data sheet (retrieved 19 October 2026)
  2. Skyguard 5 litre liquid rubber (retrieved 19 October 2026)
  3. Gorilla Waterproofing Liquid Black (UK) (retrieved 19 October 2026)
  4. Bostik Waterstop flexible waterproof coating (retrieved 19 October 2026)
  5. HSE paint and coatings FAQ (retrieved 19 October 2026)
  6. HSE latex allergy (retrieved 19 October 2026)
  7. Bauder on BS 6229:2025 (retrieved 19 October 2026)
  8. Assimilated Regulation 1935/2004 (retrieved 19 October 2026)
  9. Plasti Dip liquid electrical tape (retrieved 19 October 2026)