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Exposed Subfloor Open to Rain

KRISTIANBISHOP | Posted in General Questions on

Good afternoon, the people that have been working on our home have left it open like this for quite some time, a few months. It has been rained on many many times. I am super concerned that if we decide to lay tile or anything else actually, that it will be uneven.

Thank you in advance!

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  1. huey_ce | | #1

    Sheathing should be rated "Exposure 1", you may be able to find a legible APA stamp on a panel to confirm.

    It is expected that sheathing will get wet during transportation and construction, and Exposure 1 panels are intended to maintain their integrity during such wetting.

    Those panels are OSB, and when OSB gets too wet for too long sometimes the edges swell which can interfere with the installation of flooring. Manufacturers seal the edges of modern panels to try and prevent this, the problem use to be a lot worse. Modern products that are targeted at subflooring, like advantek, actually hold up very well compared to older panels. From your pictures these look like standard OSB panels.

    If the edges do swell they can always be sanded or planed down. This can be a PitA because you also have all of the edge fasteners waiting to tear your sand paper or chew up your planer blade, I know from personal experience when I use to work for a carpenter.

    At the end of the day if there are issues its not the end of the world. There may be some remedial work, or there may need to be some mechanical dehumidification required before finished flooring goes down. But at the end of the day don't pay any extra invoices for the remedial work. Scheduling is your contractors responsibility, and any extra work because the house wasn't dried in quick enough should come out of their pockets.

  2. Expert Member


    Unfortunately, it's almost impossible to assess the damage to OSB sub-floors from photos on the internet. As Huey said: it may need some minor remediation, but probably isn't structurally compromised.

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