Moisture Resistant MDF: What Is It and How Is It Used?

When looking to use MDF boards within a kitchen or bathroom, there is a substantial risk that they will be ruined by warping due to high levels of moisture. A great solution is to use moisture-resistant MDF, which is specifically designed to perform well within humid environments. In this guide from Building Materials Nationwide, we’ll take a look at how moisture-resistant MDF is made, its uses within furniture and construction, and how to paint and cut it.

What is MDF?

MDF, also known as medium-density fibreboard, is an engineered wood product used throughout the UK, typically for furniture and non-structural building elements. It is made from waste wood fibres like sawdust and shavings, which are mixed with resin and wax, and shaped into boards under both heat and pressure. 

This has the added bonus of being environmentally friendly, by using components that would otherwise have been wasted. Regular MDF has very poor water performance, soaking up moisture and leading to swelling and distortion. This means that standard MDF is not suitable for use in wet conditions.

What is Moisture Resistant MDF?

Moisture-resistant MDF is manufactured to be used in environments with risks of moisture or humidity, avoiding the issues that would plague traditional MDF. This is achieved by using a moisture-repellant resin during manufacture, ensuring that an MDF board is not prone to absorbing moisture to the same extent. Within the UK, moisture-resistant MDF will have a green hue on smaller boards, this is merely for identification and doesn’t have anything to do with the production method.

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Can You Make Regular MDF Moisture Resistant?

It is possible to add moisture resistance to traditional MDF, through the use of quality wood sealants. This will need to be applied on top of an MDF primer, and a couple of coats will be required. 

Is Moisture Resistant MDF Waterproof?

When looking to use moisture-resistant MDF boards within a project it’s important to remember that resistance is not the same thing as waterproofing. While it will be enough to ensure steady performance in humid environments and places with the risk of some moisture such as kitchens and bathrooms, no MDF will be suitable for exterior use or submergence in water. Boards sold as water-resistant MDF will fare equally to moisture-resistant, as it is simply a different way of describing the same product.

What is Moisture Resistant MDF Used For?

The uses of moisture-resistant MDF are quite similar to the uses of regular MDF, except specified within environments that possess high levels of humidity.

Furniture

Moisture-resistant MDF is ideal for creating bathroom and kitchen furniture, such as cupboards, shelving, and kitchen countertops. MDF has many benefits, being easy to cut into shape and substantially cheaper than using solid wood. It is dense, with enough strength for regular furniture usage. Opting for a moisture-resistant MDF will allow furniture to function well within the humid environments of a kitchen or bathroom.

Kitchen and Bathroom Cladding

MDF is also used for panelling and cladding purposes within a building, due to the ease with which it can be carved into different shapes and decorated. Things like architectural mouldings, window sills, and skirting boards can all be made with moisture-resistant MDF and used within a bathroom or kitchen environment. 

What Sizes of Moisture Resistant MDF Are Available in the UK?

Due to its construction process, MDF sheets and boards can be hot-pressed and cut into a wide range of dimensions. While MDF can be cut to the required size without losing its look or strength, its thickness will need to be selected in advance. Much like traditional MDF boards, moisture-resistant MDF can be bought in different thicknesses, such as 6mm, 9mm, 12mm, 18mm, 22mm, and 25mm. Which of those you’ll need will depend on both aesthetic needs from cladding and the strength needs of a piece of furniture.

Can You Paint Moisture Resistant MDF?

All MDF, including moisture-resistant models, will need to be primed before it can be painted. This is to stop the paint from soaking into the MDF. You’ll need to cover the MDF with a specific MDF sealant, after which it can be safely painted. While you will now technically be able to use water-based paint, it is probably best to avoid the risks of damage and opt for oil, acrylic, or latex-based paint. You should sand and dust between coats, ensuring a smooth surface and a clean look. MDF will almost always be painted or otherwise covered during use.

Can You Cut it?

You can cut moisture-resistant MDF much like regular boards, and thanks to the consistent look of MDF it can easily be cut and sculpted into a wide variety of shapes. When cutting MDF it’s vital to use protection, due to the potentially harmful dust that will be thrown up during the cutting process. You should cut MDF in a well-ventilated room that can be thoroughly cleaned afterwards and should wear a gas mask and safety goggles throughout. You should also wear gloves and a tight long-sleeved top.

For cutting straight lines into MDF, you should use a circular saw with a fine-toothed blade. A blade with a carbide tip and a high cutting speed will ensure a clean cut, as MDF can splinter if you use harsher blades. For curved cuts you should use a jigsaw with a bi-metal cutting blade, preferably one with lots of small teeth, to help ensure clean cuts.

Our Range of MDF for Sale

Building Materials Nationwide works with customers throughout the building industry and beyond, offering a comprehensive range of building products delivered across the UK. We aim to take the hassle out of sourcing products, operating as a one-stop supplier for customers, with everything sold at competitive prices. 

Through our website, you’ll find a wide selection of sheet materials including MDF for sale, alongside our full range of timber, drylining, insulation, and more. Customers within the building industry can take full advantage of our trade accounts, with each account holder having their own dedicated account manager, who’ll be able to help them organise large or specific orders through our network of suppliers. Sign up for a trade account through our website today.

If you found this overview useful, you may enjoy our guides to carcassing timber and timber sizing.