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Advice and installation

 
 
 

Advice and installation

General recommendations

  • Store and install in a dry environment
  • Remove surface condensation
  • Install an expansion joint between each panel and assemble in a way that does not hinder small displacements.
  • Choose the right class of glue bond according the plywood’s intended use
  • Pack on-site to allow the plywood to return to its hygroscopic equilibrium point after transport
  • Heat up the premises gradually
  • Maintain a constant level of humidity in the air, particularly in air-conditioned premises.

Plywood storage

Plywood is an exceptionally strong and durable material. Nonetheless, to ensure that it retains its specific properties and numerous qualities, it is important to adhere to certain rules in terms of logistics, usage and installation. With this in mind, quality of storage is a crucial factor.

Plywood panels are not fragile. However, a minimum amount of care is required when storing them. They must be stored:

  • flat
  • on a level floor
  • slightly raised from the floor (support bars or brackets must be no more than 80 cm apart)
  • preferably away from humidity

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BASIC RULES

  • Storing the plywood in adequately heated premises with no significant hygrometric variations prevents the absorption of humidity that can cause panels to warp. However, this phenomenon is reversible and does not affect the mechanical characteristics of the products.
  • In the event of temporary outdoor storage, stacks of plywood must be protected by a covering that is waterproof but permeable to vapour.
  • Storing plywood on its edges should be avoided, particularly when the edges are machined.
  • To prevent soiling, the top of the stack must be protected.

 

Exterior wall coverings

The physical properties and great stability of plywood mean that it can be used for exterior wall coverings. Plywood panels used for this purpose must meet the requirements of DTU (Unified Technical Document) 41.2 and be labelled as complying with bonding class 3 (exterior applications). Plywoods that meet the NF EXTERIEUR CTB-X Bardage (cladding) standard fulfil these requirements.

General installation rules are provided in DTU 41.2 « Wood-based exterior wall coverings ».

BASIC REQUIREMENTS
  • Tropical woods and indigenous hardwoods: One « class 2″ face (according to NF EN 635-2, guaranteed by NF Extérieur CTB-X)
  • Softwoods: One « class 1″ face (according to NF EN 635-3, guaranteed by NF Extérieur CTB-X)
  • A minimum of five plies
  • Thickness: 10 mm minimum (in the case of grooved panels, the thickness is measured from the bottom of the groove).
  • The next ply under the face must have no overlapping or open joints, open splits measuring more than 5 mm at the panel’s edge, or loose knots with a diameter of more than 10 mm.

Téléchargez le PDF « Design and installation of plywood (standard NF Extérieur CTB-X) as an exterior wall covering »

Flooring

The high physical and mechanical performance of plywood, notably in terms of flexural strength, make it particularly well suited to the construction of load-bearing floors.

General installation rules are provided in DTU 51.3 « Wood and wood-based flooring ».

BASIC REQUIREMENTS

 

  • Compliance with the requirements described in standard NF EN 12871 (revised in 2013) « Wood-based panels – Functional specifications and requirements for load-bearing panels used in flooring, walls and roofing »
  • Panels marked « S » (structure)
  • Declarations of Performance and CE marking certifying the plywood for structural use (2+ assessment system)

Téléchargez le PDF « Design and installation of plywood (NF Extérieur CTB-X standard) as a flooring material »

Shear walls
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In wood-frame structures, plywood can be used to create a sheer wall and for bracing purposes. In such cases, the panels must meet the requirements of standard NF EN 636-3 (bonding class 3, exterior applications): the NF Extérieur CTB-X quality mark certifies the plywood’s compliance with this standard.

General installation rules are provided in DTU 31.2 « Construction of wood-frame houses and buildings ».

BASIC REQUIREMENTS
  • Compliance with the requirements described in standard NF EN 636-3
  • Panels marked « S » (structure)
  • Declarations of Performance and CE marking certifying the plywood for structural use (2+ assessment system).

Téléchargez le PDF  « Design and installation of plywood (NF Extérieur CTB-X standard) for sheer walls »

Roofing

Whether it be for warm roofs (insulated or not) or ventilated cold roofs, plywood can be used as a roof covering substrate or waterproofing substrate. Its mechanical characteristics and resistance to humidity must be suited to this type of use.

Panels intended for these applications must comply with standard EN 12871. NF Extérieur CTB-X plywood meets the requirements of these applications.

General installation rules are provided in the 40-series DTUs relating to roofing, DTU 43.4 in particular.

BASIC REQUIREMENTS
  • Compliance with the requirements described in standards NF EN 636-3 or NF EN 636-2
  • Panels marked « S » (structure)
  • Declarations of Performance and CE marking certifying the plywood for structural use (2+ assessment system).
  • Bonding class 2 or 3 depending on the case

Téléchargez le PDF  « Design and installation of plywood (NF Extérieur CTB-X standard) as a roofing material »

Interior fittings and wall linings

Plywood is suited to a wide array of interior fitting applications. The advantage of this material is that it combines the elegance of natural wood with excellent technical characteristics. It is available with various types of finish (varnished, veneered, laminated, etc.) and is an effective solution for all creative requirements.

Depending on whether the panels are to be used in a dry or humid environment, the bonding class must fulfil the requirements of standards EN 636-1 or EN 636-2, respectively.

It should be underlined that, regardless of the intended use of this category of plywood, these are not structural applications. Standard practices for using plywood as a lining are provided below.

SPECIFIC SOLUTIONS
  • Fireproof plywood: manufactured specifically for buildings that are subject to fire regulations
  • Veneered plywood: used for wall coverings, ceilings, doors and furniture
  • Flexible plywood: takes on a wide variety of shapes to cater for all furnishing and decoration requirements
  • Moulded plywood: used for the manufacture of chairs, point-of-sale displays and interior fittings.

Téléchargez le PDF « Design and installation of plywood (NF Extérieur CTB-X standard) for wall linings »

Formwork

Plywood is now the material of choice for concrete formwork, thanks to technical characteristics that make it well suited to the purpose (water resistance, high mechanical strength, good thermal insulation, chemically neutral, lightweight), but also its ease of use.

 

Sanded raw plywood, panels coated with phenolic films allowing them to be reused numerous times, flexible panels, moulded sections… the various options available make it possible to set up formwork for all kinds of structure and to meet strict requirements when it comes to the surface appearance of concrete.

Not only is plywood a reliable material widely reputed for its performance, it has also proven itself to be a very cost-effective option, especially when it is reusable.

When plywood is employed for such applications, the quality of its veneers and face plies must be proven (standard NF B54.162). The quality of the surface coating must also be guaranteed (standard NF EN 311) and the ability of its faces and coating to withstand contact with concrete must be certified. The NF Coffrage CTB-C certification mark vouches for the plywood’s compliance with the requirements inherent to concrete formwork.

BASIC REQUIREMENTS
  • Compliance with the aforementioned standards (see standard NF-Contreplaqué COFFRAGE CTB-C)
  • Ability to provide the required surface appearance
  • Coating quality and suitability for formwork
  • Ability to be reused
  • Resistance to bad weather

Téléchargez le PDF « Design and installation of plywood (NF Extérieur CTB-X standard) as a roofing material »