Water test between Floor Underlay OSB and MDF

[Alan]

Before building a wood project that would live outside I wanted to see the effects that high moisture levels would have on the product.

The project was the Halloween Hanging Mobile Project

The test was done on a piece of 5/16 inch OSB floor underlay material and a piece of 1/2 inch MDF.

Both pieces were submerged under water, after 48 hours the effects had taken full effect and changed very little after that. Total soak time was 5 days though. The results were dramatic! The MDF swelled to twice its thickness (one full inch) where the OSB only increased by 0.005 of an inch which was due to a slight roughening of the one glass smooth surface, the OSB board remained as strong as it originally was.

Even though the MDF swelled to twice its thickness the width remained the same. At this point the MDF was mushy and layers could easily be separated. See below for some pictures of the results.