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outie windows – pressure treated bucks?

mikedim | Posted in General Questions on

I am building outie window bucks out of 2x lumber to integrate with my 4″ exterior insulation.  Im wondering if there is any wisdom in using pressure treated lumber for this application, just as extra security.  I see exterior window frames among the first places for rot to happen on older houses in the area.  Granted, if all the flashing is done properly this shouldn’t be an issue.  However, with the cost being similar is there any harm in using PT?

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  1. Expert Member


    No reason not to, although there are a couple of things to look out for.

    Most pt. lumber in the States is still ACQ. It is often wet, so it checks and twists as it dries. It also has a galvanic reaction with many fasteners and hardware. If you can, try to source PMS lumber which doesn't have these problems.

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