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Waterproofing MDF for Bathrooms: Ultimate Guide

Waterproofing MDF for Bathrooms, MDF (Medium-Density Fiberboard) is among the most inexpensive materials that are not waterproof but with several uses. You can use it for countertops, furniture, decorative panels, flooring, soundproofing, baseboards, cabinetry, signage, etc.

Can You Use MDF In A Bathroom

Waterproofing MDF for Bathrooms

MDF is susceptible to water and moisture damage. Many people don’t know whether to use it in the bathroom. So, can you use MDF in a bathroom? Yes. MDF can be used in the bathroom without any issue, but with the precaution that you seal it with oil-based sealers and some coats of poly to make it waterproof, preventing warping and shrinking.

In this writedown, we take you through how you can make your MDF water-resistant to make it suitable for use in the bathroom and other humid areas. Let’s get started.

How to Waterproof an MDF for the Bathroom

It is important to note that there are waterproof MDF in the market. However, they come with a hefty price compared to the standard MDF. As a result, waterproofing your standard one has become an easy option and easily attainable. 

Waterproofing your MDF to withstand high moisture levels has two approaches. First, you can use MR (moisture resistant) MDF or make it waterproof yourself. Regardless of your choice, MDF is not water-resistant nor waterproof but moisture-resistant. Hence, it is vulnerable to swelling and warping.

Purchase MR MDF

Moisture-resistant MDF is designed for interior use where moisture is an issue. Unlike the standard MDF, it is made using a moisture-repellent resin. Waterproofing MDF for Bathrooms is easy to sand and mill and absorbs well to paints, veneers, and adhesives.

Therefore, it is perfect for bathrooms, kitchens, laundry rooms, and boilers but slightly pricier than its counterpart. The Moisture resistant characteristic makes it worth the value of your money.

Another approach is creating a waterproof MDF with quality wood sealant, varnish, and moisture-resistant paint /stain to safeguard it from water and humid ruins. Remember, waterborne polyurethane doesn’t bind efficiently to the MDF’s surface.

Steps to Waterproof Your MDF

For a start, choose a latex primer or MDF-designed primer. Due to the MDF being moisture resistant and not water-resistant, please steer clear from water-based polyurethanes and finishes. Go into the manufacturer’s website for detailed information and select products that are 100% waterproof and not simply water-resistant.

Step 1

Choose a quality brush of proper width for grooves, edges, and fastening holes. In case the area is large, a quality 3/8-inch nap roller is recommendable for uniform application and surface finish.

Step 2

Stir or shake the primer or sealer as per the instructions. Pour an adequate quantity into a spotless paint tray. Roll the roller in the paint or dip the brush in color based on the one you’re using.

Step 3

Begin by applying the sealer/primer to the grooves, edges, and screw holes to cover the exposed wood. Ensure there are no puddles or drops. For larger areas, use the roller in a “W” or “Z” pattern to apply the primer/sealant, ensuring it covers the MDF evenly without drops.

Examine for any uncovered spots; if there is none, let it dry as per the manufacturer’s guidelines.

Step 4

Keep the brush and the roller moist if you will apply a second coat or clean according to the sealant instructions. 

Tip: You can apply more than one or two coats but ensure you allow the sealant to dry in between as the manufacturer recommends.

Step 5

Once the single or double coats of the primer or sealer dry, Apply one or two coats of waterproof paint adhering to steps 1 to 4 above, and let it fully cure for at least 3 days to make your MDF waterproof.

Tip: Waterproofing will secure your MDF from moisture and water but not from extended absorption in water

What Ways Can You Make MDF Waterproof?

You can apply several products on the board to make them more resistant to water. Let’s dive in to see what is available.

Wood Sealant

It is the primary product to improve the water-resistance levels of your MDF. Both categories of MDF boards bind well with paint and stain. You can use a brush, roller, or sprayer to apply the finishes. 

Nonetheless, particular finishes require slight sanding of the MDF before applying the finish. Therefore read the manufacturer’s label for instructions.


Waterproofing MDF for Bathrooms comprises resins, solvents, and drying oils, creating a scratch and water-resistant coat. It is popularly used to seal the wood, penetrating the porous surfaces and making them water resistant. Use an exterior-grade impermeable varnish to seal MDF for great results.


Shellac is used to cover knots so as not to show through the paint, but in MDF, it bonds with the surface wood fibers to make a more water-resistant finish. Once dry, cover it with waterproof paint to boost its moisture protection.


They come in a variety of both water-based and oil-based formats, combined with a top coat to make MDF more water resistant. However, for interior and decorative impacts, you can apply it plain. Waterproofing MDF for Bathrooms is significant to note that it doesn’t enter intensely into MDF

Epoxy Sealant

It offers an impenetrable water-resistance seal to any place they apply, including MDF. It is resistant to peeling, scuffing, fading, and blistering. They are ant-UV and highly durable. They can protect MDF from water absorption.

Drying oil

It is standard vegetable-based oil mixed with oxygen to gradually harden and dry, such as poppy seed, tung oil, linseed, etc. When applying it to seal your MDF, use an oil-based topcoat for excellent paint adherence. First, ensure the drying oil has dried thoroughly before administering the coat.

Liquid Latex

Use latex-based paints as they’re fast dry, have low VOCs, and offer a waterproof seal that binds well to MDF. It serves both as a sealer and a water-resistant topcoat.

Can you use MDF in the bathroom? -Verdict

Waterproofing MDF for Bathrooms

Yes. Proper sealing allows the MDF board to be used in a bathroom without any issues. This article extensively explains how you can make your standard MDF waterproof using various options. With that said, it is crucial to note that sealing should be done before installation using an oil-based sealer and a few layers of poly sealer for an incredible result in protecting your MDF from moisture and water damage.