Sheet materials: a selection chart

At a glance

Data-sheet requirements or means for single products, in N/mm²: examples, not design values. The American ratings are for veneered-panel cores.

The chart: nine materials side by side

First, what each material is and the standard that describes it, with what we saw of its status. Then what the data sheets say about damp, fire and formaldehyde.

And the same rows for damp conditions, fire and formaldehyde, as the data sheets state them:

The columns are what the documents say, not a verdict. ‘Default class’ is the class a board can be given without testing when it meets a minimum density and thickness and is mounted as the Commission Decision describes (see the fire section). A ‘requirement’ on a data sheet is the minimum the maker guarantees; a ‘mean’ is an average for one product.

The numbers: what the data sheets give

Every figure below comes from a data sheet or a handbook table we read. Most data-sheet figures are requirements: the least the maker says the board will achieve, so real boards are usually stiffer and stronger. The plywood figures are means for one formwork-grade product, which is why plywood looks stiffer than anything else. They are examples for scale. They are not design values, and the standards they come from describe product properties, not characteristic values for structural design.

For scale, the US Wood Handbook gives the following for typical North American products. They are older, they come from several mills, and they are not UK products.

Thickness and size. The tolerance on thickness decides whether two boards sit flush at a joint, and the sheet size decides waste. The sheets read give:

The sheet sizes shown are the sizes in the sheets read: they are a starting point for the designing to standard sizes sheet, not a statement of what a partner can supply.

Which board for which job

Pick the board from the question, then write down the standard, the type and the document. The table below ties each job to what the sources say. It is a guide to what to ask, not a rule.

The American woodwork standards also say that formaldehyde emission regulations should be researched before shipping into an unfamiliar area (AWS 1.3.5). The studio coordinates manufacture through partner workshops, so the board supplier, the data sheet and the declaration of performance are the partner’s to supply, and the specification should ask for them.

Reaction to fire: where the boards sit

Ordinary wood-based boards are not non-combustible, and the class they carry matters when they line a wall or a ceiling. In England, Approved Document B asks surface linings to meet class B-s3,d2 in other circulation spaces (which in volume 1 include the common areas of blocks of flats), C-s3,d2 in other rooms, and D-s3,d2 in small rooms (volume 1 Table 4.1; volume 2 Table 6.1, small rooms being up to 4 m² in residential accommodation and, in volume 2, 30 m² in other buildings). Parts of walls may be of lower performance, but no worse than D-s3,d2, over up to half the room’s floor area and a stated maximum area (volume 1, 4.4; volume 2, 6.4). The same paragraphs say a wall does not include doors and door frames, architraves, cover moulds, picture rails, skirtings and similar narrow members, or fireplace surrounds, mantle shelves and fitted furniture (4.3, 6.3). The 2025 amendment removed the national classes for reaction to fire: only the European classes are used now. The Decision’s classes also cover veneered, phenol-faced and melamine-faced panels (footnote 5).

Commission Decision 2007/348/EC, as it stands on legislation.gov.uk, lists the class that wood-based panels can be given without testing. These are minimum densities, thicknesses and mountings, and a board that is thinner, lighter or mounted differently does not get the class:

So a plain board 9 mm or thicker, fixed directly to a class A1 or A2 substrate, defaults to D-s2,d0. That meets the small-room class and the lower-performance allowance, but it does not reach the C-s3,d2 asked for in other rooms, or the B-s3,d2 of circulation spaces. A board with a declared class of B-s1,d0, such as the fire-retardant MDF read, does. Whether a given panelling build, with its fixing, air gap and finish, achieves the class is for the fire engineer and the test or classification evidence: see the sheet on the fire performance of wall panelling. This is guidance, not fire advice.

Paperwork and standards: how to read the labels

What to ask for with any board, in the order a reviewer will want it:

• The standard and type, with edition: for example EN 622-5 type MDF.H, EN 312 type P2, EN 300 OSB/3, EN 636 for the conditions of use, EN 438-4 compact.
• The declaration of performance (EN 13986) for the board and thickness supplied. The P2 declaration read lists reaction to fire, formaldehyde release, biological durability and thermal conductivity, and shows ‘NPD’ (no performance determined) for several properties. Marking: the sheets read carry CE marking; we did not see UKCA marking on them, so ask what mark the supplied board carries.
• The emission class and its test method (EN 717-1): E1 is the usual class stated, E05 appears on some sheets, and one declaration gives E05 as at most 0.062 mg/m³.
• The reaction to fire class for the thickness, as declared, and what mounting it applies to.
• Face grade, thickness tolerance and sizes, and for plywood the bond class and the veneer species.
• Chain-of-custody documents if the specification calls for them: see the FSC and PEFC sheet.
• Storage and conditioning: the MR data sheets say to condition for two to three days in the final environment and to coat every face before installation.

Standards change. What we saw on 5 and 6 November 2026:

The MDF decoded sheet goes further on MDF types, and the finishes on timber joinery sheet covers what goes on the board.

[MDF] to BS EN 622-5 [type MDF.H], [18] mm, [sanded], with the manufacturer's declaration of performance. Maker, product and standard edition on the shop drawing. Boards conditioned in the final environment for [two to three] days before processing and coated on all faces and edges.

[Birch] plywood to BS EN 636 for [dry / humid] conditions, bond to EN 314-2 class [1 / 3], face grade [B/BB], [E1], [18] mm, with the maker's declaration of performance. Edges [lipped / veneered / sealed].

Where improved reaction to fire is required: [fire-retardant MDF] declared Euroclass [B-s1,d0] for the thickness used, by the manufacturer's declaration of performance, and confirmed for the finished build (substrate, air gap, fixing, finish) by [fire engineer].

[Compact laminate to BS EN 438-4], [12] mm, decor [ref], with the maker's fire class for that thickness. [HPL to BS EN 438-3, [0.8] mm] bonded to [substrate] with a balancing laminate on the reverse.

Standards and sources

• USDA Wood Handbook FPL-GTR-282 (2021), Table 12-1; Architectural Woodwork Standards (2009), Section 4: US sources.
• Commission Decision 2007/348/EC (wood-based panels): Table 1, default reaction-to-fire classes.
• Approved Document B volumes 1 and 2 (England), amendments to 2026: Tables 4.1 and 6.1.
• BS EN 622-5, 312, 300, 636, 13986, 438-3, 438-4: status only; not read.

Questions we are asked

Which is best: MDF, plywood or chipboard?

None, in general. Plywood is the stiffest of the boards read (birch plywood about 7,500 to 10,000 N/mm² against 2,000 to 2,700 for MDF and 1,200 to 1,800 for P2 particleboard), MDF has the smoothest faces and edges for paint and lacquer, and particleboard has the lowest stiffness of the boards read. Pick from the job: carcase, sprayed door, damp room, fire, worktop.

Is moisture-resistant MDF waterproof?

No. The data sheets say it is for humid interior conditions and not suitable for external use, and one adds that it must be coated on every face before it is installed, especially next to damp plaster. In the cyclic test, which soaks, freezes and dries the board three times, the MR boards read swell by 15 to 19 per cent in thickness.

Is MDF fire retardant?

Ordinary MDF is not. A board of 600 kg/m³ or more and at least 9 mm, fixed directly to a class A1 or A2 substrate, defaults to class D-s2,d0 under Commission Decision 2007/348/EC. Fire-retardant MDF is a different product: the data sheets read state B-s1,d0 for 6 to 30 mm on one and B-s2,d0 or B-s1,d0 by thickness on the other.

What is the difference between HPL and compact laminate?

Thin HPL is under 2 mm and is bonded to a substrate (BS EN 438-3). Compact laminate is 2 mm or thicker and stands alone, with a solid core (BS EN 438-4); one maker describes its boards as dimensionally stable and self-supporting above 5 mm.

Can OSB be used in joinery?

The data sheets we read describe OSB/3 as a load-bearing panel for humid conditions, with stiffness of 3,500 N/mm² in the strong direction and 1,400 across. We found no source for using it as a visible or finished joinery surface, so the page does not recommend it for one.

What is the difference between blockboard and plywood?

Blockboard has a core of timber strips between veneers, which the American woodwork standards call a lumber core, rated excellent for bending strength and good for the other properties in their table. Plywood is veneers throughout. We found no strength figure for blockboard in a source we could read.