CalFinder Q&A: MDF Instead of Drywall?

From on October 02, 2008 in

A question from one of our faithful readers, Danielle Duckworth.

“I’m just wondering if you can use MDF as a paneling type? What I mean is can you use it like you would use drywall? If so, what would you use to putty between the seams and fill in the nail holes?”

Dear Danielle,

You may be able to use MDF in place of drywall, although there are a few things to consider. First off, building codes require that panels thinner than 1/4” be backed with a non-combustible material (i.e., drywall, gypsum wallboard). Much depends on which MDF material you are using. Oftentimes, decorative MDF wall panels do not meet these codes. Even if you are using (as I imagine you are) thicker, 4’x8’ panels, fire safety is something to think about. That being said, MDF is often powder-coated to protect against fire; you’ll need to know your product’s history.

As for installation, decorative MDF is usually made with a tongue-and-groove or “lap” design, meaning you shouldn’t have to caulk or putty seams. However, unfinished MDF sheets will need some work. You should leave a small gap (1/16”) between panels. You can fill these with a painter’s putty or caulking. Note that, should you use caulk, you will need latex acrylic caulk plus silicone. The silicone will give the caulk more flexibility and strength as the panels dry and shrink up. Also, be sure to prime MDF before painting.

Finally, when painting MDF, it is easy to leave noticeable streaks and brush lines, possibly resulting in a good deal of sanding. Also, MDF should not be used in bathrooms and other high-moisture or humid areas.

Hope this helps and thanks for writing in!

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