MDF for Exterior Use

Medium density fibreboard has been developed by some manufacturers into a more advanced product. With greater durability and dimensional stability, some can be used outdoors and also offer resistance to fungal decay and termite attack.

The wood fibres are often recycled as a by-product of other operations and procedures. One manufacturer lists the composition of materials in their panel as including wood, phenolic resin, wax, zinc borate plus others, although specifically no added urea formaldehyde, which is considered toxic.

Exterior applications with these advanced panels can include, door skins, furniture, signage, cladding, millwork and fascias. Due to the moisture resistance of the panels, they can also be used for internal wet applications such as bathrooms, pools rooms, or labs.

Panels are commonly available in a range of thicknesses up to 3/4”, although, some manufacturers may provide a maximum of 1 1/4”.

Densities may vary slightly from one product to another depending upon composition and manufacturing method but are typically stated as 45 to 50 lbs/ft3 or a specific gravity in the region of 0.75, check data sheet of specific panel for precise values.

The panels can be readily processed by cutting, sanding, machining, routing they can also be glued and coated. The processing of the panel will generate dust particles and this should be contained and managed using an extraction system.

Check the fire rating of the individual panel selected.

Stainless steel fittings grade 304 or 316 are the best choice for fasteners, hinges, and fittings for exterior fibreboard applications. Although galvanized steel and some corrosion resistant copper and aluminum alloys may also be considered.

The table below highlights the performance of one such product against standard MDF and plywood.

Studying the data sheets from panel manufacturers will assist in the selection of the best product for your application.