Fire Retardant Plywood

What fire retardant plywood is

Ordinary plywood burns. Fire retardant plywood has been treated, by forcing chemicals into the timber under pressure, so that it resists catching and slows the spread of flame across its surface. The treatment goes right through the board rather than sitting on the face, which is the important part: the protection is in the timber itself, not in a coating that can be sanded or cut away.

It is important to be clear about what that does and does not mean, because the words get used loosely. The board is not fireproof, it is not a fire barrier, and it will not stop fire passing from one room to the next. What it does is buy time and limit how quickly flame travels across a wall or a ceiling lining, which is precisely what the building regulations are concerned with when they ask for a class.

Fire rated plywood: what Euro Class B-s1,d0 means

This is the classification you will be asked for, and it breaks into three parts that are each doing a separate job.

B is the reaction to fire. The scale runs A1, A2, B, C, D, E, F, where A1 does not burn at all and F is unclassified. B is the highest class a timber product can realistically reach, and it sits well above untreated plywood, which comes in at D. In plain terms it means the board contributes very little to a fire that has already started near it.

The s1 is smoke, and it is the lowest of three smoke categories, so the board gives off very little of it. That sounds like a secondary concern and it is not. In a building where people have to find their way to a door they cannot see, smoke is what stops them, and a lining that fills a corridor quickly is a worse problem than one that burns slowly.

The d0 is burning droplets, and it is the best of three. It means the board does not drip flaming material as it burns. Droplets are how a fire in a ceiling gets down onto furniture, a floor covering or a person underneath, so d0 matters most on anything overhead.

Put together, B-s1,d0 is a strong classification, and it is the one commonly written into specifications for wall and ceiling linings in commercial and public buildings. If a specification quotes it at you, the board on this page is what it is asking for.

Reaction to fire is not fire resistance

These two get confused constantly and they are different things. Reaction to fire, which is what a Euro Class describes, is about how a material behaves when fire reaches it: does it catch, how fast does flame spread, how much smoke, does it drip. Fire resistance is about how long a whole construction holds back a fire, and it is measured in minutes against a wall or a floor assembly, not against a single board.

So a B-s1,d0 board does not give you thirty minutes of anything on its own. If your specification is asking for a period in minutes, it is asking about the build up as a whole and you need to look at what the assembly is, not just which sheet goes on the face. If it quotes a letter and two codes, it is asking about the board, and this is the board. Read which one you have been handed before you order: a letter and two codes means this board answers it.

When you need it

Whenever a specification, a fire safety certificate or a building control officer asks for it. In practice that means commercial fit outs, public buildings, schools, places of assembly, escape routes, and the common areas and corridors of apartment buildings. It also turns up on exhibition and event work, where the venue sets its own requirement and will turn away a stand built from untreated board.

At home, it is the board to use wherever you want a lining that resists catching and slows flame spread, such as a garage or workshop lining, a boiler cupboard or a home cinema wall. Where no rating applies at all, untreated birch plywood gives you the same dense, void free core without the treatment, and marine plywood is the sheet to choose when the job is wet rather than fire rated.

The fire retardant plywood we stock

We stock one board, chosen because it matches the classification most specifications ask for: 18 mm fire retardant birch plywood in the 2440×1220 mm sheet, B/BB faced and treated to Euro Class B-s1,d0. It is made for wall and ceiling linings, fit out panels, joinery on escape routes and exhibition stands.

Because the core is birch you get everything that comes with birch underneath the treatment: a dense void free board, a clean edge if you are leaving it exposed, and screw holding that no softwood board matches. The treatment is pressure impregnated through the whole board, so it can be cut to size on site without losing its rating. A sheet weighs 36.4 kg, the same as untreated birch of the same size, so it is a two person lift and nothing about the treatment changes how it handles.

Working with it

Cutting a treated board does not remove the treatment. Because the chemistry is through the timber rather than on the surface, cut edges, rebates and exposed plies hold the same classification as the face, so you can break a sheet down without having to think about it. That is the practical advantage of a pressure treated board over a coated one.

What can affect the rating is what you put on top. Some paints and coatings change the surface behaviour of a treated board, and on a job that has to be certified that is a real risk rather than a theoretical one. Ask whoever supplies the finish whether it is compatible with a Class B substrate, and get the answer in writing if the job is being signed off.

Keep the paperwork that comes with the delivery. On a certified job you will be asked to show the certification for the board, usually at the least convenient moment, and it is far easier to file the documentation when it arrives than to chase it afterwards.

How much does fire retardant plywood cost?

A fire retardant board costs more than the same untreated sheet, because the treatment is forced right through the timber under pressure and the board carries a tested classification. What you are paying for is a rating that survives cutting, so there is no coating to reapply to edges and no extra product to buy. Compare boards by the classification your job needs, not only by the sheet price. The calculator on the product page works out how many sheets your wall or ceiling area needs, and the price for your quantity shows in the cart.

Fire retardant plywood in Dublin and across Ireland

The board is stocked in our North Dublin warehouse and delivered across Ireland. Check the class your specification or fire safety certificate calls for before you order: if it asks for B-s1,d0, this board meets it. Keep the delivery paperwork with the job file, since that is what a certifier will ask to see. For every other grade, from birch to marine and softwood sheets, see our full plywood range.