Drilling drainage holes into TruFlor subflooring


Can you tell me if there are any potential issues with drilling 1/2″ holes in “TruFlor” subflooring in order to drain stagnant rain water…?
Dean Magee


Thank you Dean for your email and your very good question. First, let me say that there are no issues with drilling a hole to allow water to drain away. Having said that you need to consider “where to drill” and avoiding high traffic areas such as the center of a hall or the center of a door way would be a best building practice. In a closet or close to a partition would be ideal as opposed to the center of a room.

Generally a broom or squeegee is used to move the water towards the hole. Take a look at this APA (The Engineered Wood Association) file that covers that topic on page 2 along with a suggested repair method after everything has dried completely. Drilling a hole will not affect the structural properties of the sub-floor. Just an FYI that you may see some edge swell. That is typical of commodity OSB and plywood when panels have been exposed to rain. The floor should be allowed to dry completely before attempting to sand any joints. Do any sanding that might be required just before the finished floor is to be installed.

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