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Medite Exterior is an MDF panel developed specifically for use in a wide range of external applications in accordance with MDF-H2 as defined in EN 622 part 5 and gives all the design freedom of Standard MDF.
Medite Exterior (EN 622-H2) is used as a substitute for softwood, hardwood, plywood, plastic and metal in non-stressed applications. It can be used for a wide range of external applications including: external signs, shop fronts and external woodwork including fascia's, exterior mouldings, door parts – raised and fielded panels, garden furniture components, exterior display stands, marine craft interiors and sports score boards.
HOW EXTERIOR IS MEDITE EXTERIOR?
All wood and wood-based products react to moisture and Medite Exterior is no exception. Wood cells expand and shrink slightly in width and length as they absorb or lose moisture. This phenomenon is not fully reversible, as relieved stresses do not completely recover. Moisture changes in wood may arise from sustained changes in relative humidity, immersion or lodgement of water, any or all of which lead to absorption by capillary action. If the moisture change is not uniformly distributed in the wood, relatively strong stresses can develop which will affect the wood’s physical properties. For example, these stress imbalances can twist construction lumber and warp panel products such as plywood and Medite Exterior. The specially formulated polyurethane resin, together with the patented manufacturing process used in the production of Medite Exterior, increases the physical properties of MDF to create a premium composite panel for demanding conditions. Medite Exterior has undergone accelerated weathering tests as per British Standard 3900 F3.
D4 Classification Medite Exterior meets the requirements of class D4, durability category, of BS 4965, making it suitable as a substrate for decorative laminating plastics and veneers in areas of frequent prolonged exposure to running or condensed water. Medite Exterior, as with all wood products in external applications, must be coated on all surfaces and edges to control both moisture uptake and moisture loss. (Refer to page 13 Sealing & Painting of Medite Exterior)
Important
We request you to read fully the document " Medite Exterior Technical Guidelines" before starting any project.
10. SPECIAL NOTES
1. It is important that boards are allowed to condition before use. See p.6 for further details.
2. All uncoated edges and surfaces of prefabricated components must be fully coated prior to assembly or exposure to weathering.
3. To aid with edge sealing, all edges must be rounded to a minimum 3mm radius.
4. Solvent-based sealers are particularly recommended for initial coating of the board. However, if a water-based primer is used, it should be force dryed to maintain the smooth quality of the board surface, before applying the subsequent coats.
5. Certain transparent or clear stains / topcoats are not recommended due to their potential for degradation by ultraviolet light. Exterior coatings with UV inhibitors are available and must be used. Paint manufacturers should be consulted as to suitability.
6. Design of assembly must be such that any lodging of water on any area or section is avoided.
7. Sealing and painting of one side only is not recommended as the unpainted side of the panel will be unbalanced by the painted side. This will allow direct access by moisture into the unpainted side of the panel creating conditions for warp, expansion and buckling of the panels ‘in situ’.
8. All fasteners must be corrosion resistant.
9. Mitre joints are not recommended due to the difficulty in coating sharp edges. Edge to face type joints offer a similar aesthetic effect, with improved coating and edge protection.
10. It is strongly recommended that a coating maintenance programme be adopted. Refer to coating manufacturers’ recommendations.
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