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Can You Put Plaster Over MDF Board? (How To)  

There are often areas that you want to plaster that are not ideal for various reasons and one of them is on MDF board.

Plastering over MDF board is not a good idea as the plaster will cause the MDF to swell as the moisture is absorbed out of the plaster. Not only will the MDF rot, but the plaster will crack and crumble, eventually falling off completely.

Man checking board

There are ways around the problem but the plaster will ultimately fall off when you plaster over an MDF board. Repairing the plaster will be exceedingly expensive, especially if you have previously painted over the plaster.

You may be tempted to scuff the MDF boards in an effort to give the plaster something to adhere to. This, unfortunately, will not work as the MDF will still absorb the water.

What you can do is attach metal lath to the MDF boards as the lath is designed to give the plaster something to adhere to.

However, you’ll still have the problem of the MDF absorbing water from your plaster. To avoid this problem, apply a waterproof layer on the MDF boards first and then nail or screw the metal lath to the MDF board.

This way you’ll avoid the plaster drying out too quickly and making the MDF wet.

Should You Put Plaster Over MDF Board?

Man putting plaster

The advice one would give to someone wanting to put plaster directly onto MDF board is a resounding, “No Don’t Do It!”.

You can get around the problem of plastering MDF board and moisture seeping into the surface, making it rot. Apply a barrier coat of waterproofing paint or a sheet of plastic and then attach the metal lath to the MDF board. MDF is not suitable for plastering as the plaster has nothing to adhere to.

Copyright protected content owner: ReadyToDIY.com and was initially posted on December 8, 2022.

MDF board is generally not suitable for plastering and that is the reason plasterboard was designed. It is purpose-made to accept plaster. If you can, replace the MDF board with a plasterboard if you want a smooth plastered surface.

The biggest threat to plastering MDF is moisture getting into the board and making it rot. You may think that using a primer will help to make the plaster stick, but it will only delay the inevitable and the plaster will eventually fall off the MDF board.

What Tools Do You Need To Put Plaster Over MDF Board?

Tools used for plaster

Using the right plastering tools can speed up the job, improve the final product, and provide an added level of quality to your project.

You’ll need a hawk and a finishing trowel to apply plaster to the wall. But before you do that, apply waterproofing paint to the MDF board with a paint roller. Cut the metal lath with a hacksaw or tinsnips, and then nail it to the board using a hammer. Alternatively, use screws and a screwdriver.

Make sure to measure the correct length of lath using a builders’ tape measure first.

Copyright article owner is ReadyToDiy.com for this article. This post was first published on December 8, 2022.

You’ll need a large bucket to mix the plaster and a bucket trowel to scoop the plaster onto your hawk. A plasterer’s float is used to smooth the plaster once it’s on the wall and is usually wooden, but you do get metal ones as well.

Once the plaster is on the wall and smoothed, you may need to use a jointing knife or jointer. These come in different shapes and sizes and are particular to the edges of your wall and how you want to finish the job.

A large sponge is useful if you need to smooth out a slightly rough area when the plaster is still wet. If the plaster dries and you see areas that are not quite smooth, you can use varying grits of sandpaper to get the surface to the desired texture.

What Preparations Do You Need To Put Plaster Over MDF Board?

Man putting plaster

Plastering a wall is a job best left to the professionals, as it can be quite tricky to get a great finish if you’ve never done it before.

To plaster MDF boards, make sure that you have a suitable waterproofing system that will stop the plaster from transferring moisture to the boards. Measure the MDF so that you cut enough metal lath to completely cover the boards you want to plaster.

You’ll need a large bucket to mix your plaster and preferably cover the floor with a drop sheet as the plaster can make a huge mess. This is especially true if your floor is covered with carpet.

Once you’ve waterproofed your MDF boards, screw or nail the metal to the surface so that the plaster has something to adhere to.

Make sure that you have the necessary tools to mix and then spread the plaster on the wall as well as sponges and sandpaper to ensure a perfectly smooth finish when you’ve completed the job.

How To Put Plaster Over MDF Board

confused man standing

Plastering is a lost art and usually takes years to master.

However, you can still do it if you are a novice DIY enthusiast and if you’re happy to spend a lot of time after the plaster is dry, sanding the surface to get a perfectly smooth finish.

To apply plaster to MDF board, paint the board with a waterproof primer and then apply metal lath for the plaster to adhere to. Once the lath is in place, plaster the MDF board in the same way you would a plasterboard wall.

Smooth the surface while the plaster is still wet and then sand down any imperfections once it is dry.

Make sure that the plaster is applied thickly enough so that it makes a good bond with the metal lath. Otherwise, you run the risk of the plaster cracking and falling off after a few weeks or months.

Your first two layers of plaster should be about 3/8th of an inch to just over ½ an inch (10mm to 15 mm).

The finishing coat would ideally be no more than 3/8th of an inch (10 mm) thick and you should avoid applying a single coat that is more than ½ an inch thick.

Don’t allow the plaster to dry fully between coats as it will then not bond properly to the next layer.

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ReadyToDIY is the owner of this article. This post was published on December 8, 2022.

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