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Tiling plywood with an uncoupling membrane

Updated: 21 October 2026

An orange roll will not let you tile a plywood floor this weekend if the floor still bounces. After BS 5385-3:2024 a decoupling mat can be the intermediate layer on timber, and only once that timber is rigid, dry, ventilated, and flat. This page is that decision: mat, tile backer board, or a joiner. The six listings are on the [Decoupling mat comparison](/hub/flooring-tools-and-accessories/decoupling-mat). Products Compared used The Tile Association’s account of the standard, two BAL notes, and the substrate lines on these amazon.co.uk listings, read on 19 October 2026. It is not a laboratory test. A qualifying purchase can earn a commission at no extra cost to you.

An orange roll will not let you tile a plywood floor this weekend if the floor still bounces.

Our top picks

Floor Nation FloorNation 3 mm, 5 m²

Best overall

Floor Nation FloorNation 3 mm, 5 m²
7.1/10about £57.95
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tonchean tonchean 30 m x 1 m liner

Alternative

tonchean tonchean 30 m x 1 m liner
6.8/10about £84.99
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Nassboards Nassboards orange 5 m²

Best value

Nassboards Nassboards orange 5 m²
7.1/10about £49.99
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On this page
  1. 1.Plywood is no longer a direct tile base
  2. 2.The floor still has to be stiff
  3. 3.When a mat is the intermediate layer
  4. 4.When to call a joiner or a tiler

Plywood is no longer a direct tile base

The Tile Association has urged tilers to notice the 2024 revision of BS 5385-3. Direct tiling to plywood and other wood-based boards is no longer the accepted route. The intermediate layer is an uncoupling membrane, a reinforced tanking system, or a tile backer board. The Tile Association’s FAQ and BAL technical note TN 23.24 both treat 15 mm as the minimum sheet thickness. A 9 mm underlay plywood is below that minimum. Wet timber is a poor base in the TTA summary, and a bathroom that wets the boards is also the decoupling membrane or tanking problem.

The floor still has to be stiff

The mat is a slip layer for moderate sideways stress. Vertical deflection, the bounce when you step between joists, passes through a plastic sheet. BAL technical note TN 07.24 says uncoupling cannot compensate for that vertical deflection. BAL, citing the standard for an existing timber floor, allows up to 0.8 kN per square metre of extra dead load from tiles, adhesive, and the mat together. BAL’s timber note wants screws at 300 mm centres and boards conditioned to the room. A 4 m by 3 m kitchen is 12 m², so a stated 5 m² roll does not cover it.
Floor Nation FloorNation 3 mm, 5 m²

Testsieger

Floor Nation FloorNation 3 mm, 5 m²
7.1/10about £57.95
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When a mat is the intermediate layer

Once the floor is rigid, dry, and screwed, an uncoupling membrane is one of the three allowed intermediate layers. The sheet is at least 15 mm and fixed at 300 mm centres, the void is ventilated, and TN 07.24 does not want the tile bed above the mat over 6 mm. FloorNation and Nassboards name wood, alongside concrete. That is a claim on the amazon.co.uk page, not a certificate. Tonchean is a 0.5 mm liner aimed at cement floors, so it is the wrong default for a timber overlay. Check thickness and area on the decoupling membrane buying guide before you treat “suitable for wood” as settled. A backer board is the better layer when you want a rigid board to bond to, or when thickness and area will not reconcile.

When to call a joiner or a tiler

Call a joiner if the floor bounces, if boards are rotten, if ventilation under a suspended floor is blocked, or if you cannot tell whether the joists will take another 0.8 kN per square metre. Once the floor may take a mat, the sequence is the how to lay an uncoupling membrane page. Do not start if the timber is in a wet room. The TTA summary treats timber as a poor base where the room is wet or frequently damp. A chipboard bathroom floor is not rescued by a waterproof bullet.

Common questions

Can I tile straight onto plywood?
Not as a direct bond, on The Tile Association’s reading of BS 5385-3:2024. You need an uncoupling membrane, reinforced tanking, or a tile backer board. The plywood still has to be thick enough, fixed, dry, and rigid before that layer goes down. The older habit of tiling the plywood itself is what the 2024 code, as TTA reports it, has closed.
Is 9 mm plywood enough?
No. BAL TN 23.24 and the TTA FAQ treat 15 mm as the minimum sheet. A 9 mm panel, often used to smooth worn boards, is below that line. A decoupling mat on top does not add the missing thickness or the screw pattern. Overlay with a suitable sheet at 300 mm centres, or leave the floor.
Will a decoupling mat stop a bouncy floor?
No. It is for moderate sideways movement. BAL TN 07.24 says it cannot compensate for vertical deflection. If the floor moves when you step between joists, stiffen the joists and the boarding first. A mat, a backer board, or tanking comes after that, and buying the roll first does not change the order.
What extra weight must I allow on the joists?
Up to 0.8 kN per square metre of extra dead load, in BAL’s account of the standard for an existing timber floor. That includes tiles, adhesive, and the mat. It is a check on the joists you have, not a figure printed on these amazon listings. If the span is already long, ask a joiner before you add a tiled floor.
Can I use these mats on a wet timber bathroom floor?
Timber is a poor base in wet or frequently damp rooms, on the TTA summary. A waterproof word on a listing does not reverse that, and none of these six pages shows a UKCA or EAD line. If the boards can get wet, sort the structure and the tanking before you choose a mat.
Is a backer board better than a mat?
It is better when you want a rigid board to tile to, or when the mat listing will not state thickness and area together. A mat is the layer when the floor is already rigid and you want a slip sheet for sideways movement. Both fail on a bouncy, damp floor. Reinforced tanking is the third option, for rooms that must stay watertight.

Related pages

Best decoupling membrane in this set

Decoupling mat

Decoupling membrane: listing checks before you buy

How to lay an uncoupling membrane under floor tiles

Decoupling membrane or tanking for your UK wet room

Sources

Public UK sources used for this comparison. Listing prices, stars and review counts are the amazon.co.uk lines kept with these six products. Shelf date 19 October 2026.

  1. The Tile Association on BS 5385-3:2024 (retrieved October 2026)
  2. TTA technical guide (retrieved October 2026)
  3. BSI, BS 5385-3:2024 (retrieved October 2026)
  4. Schlüter UK DITRA (retrieved October 2026)
  5. Schlüter data sheet 6.1 (retrieved October 2026)
  6. Weber UK uncoupling membrane (retrieved October 2026)
  7. BAL timber and deflection notes (retrieved October 2026)
  8. NHBC wet-room substrates note (retrieved October 2026)