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Adding 2″ foam to exterior of building – window trim detail?

Mark E Thibault | Posted in Energy Efficiency and Durability on

Looking at a job: old farmhouse, solid wall construction, rough sawn 2×12 installed vertically.

Will be removing siding, adding 2″ foam to exterior.

Windows have replacement low-e windows. Will remove window trim.

Looking for ideas on window trim (PVC detail).

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  1. GBA Editor
    Martin Holladay | | #1

    If you are adding 2 inches of rigid foam to the exterior walls, the best approach is to remove all of the windows and properly flash the window rough openings. If you leave the windows in place, your risk future water-entry problems.

    Every case is different, of course. If this building is located in a dry climate, and if the building has wide roof overhangs, you may decide you want to leave the windows in place. Only you can decide whether this approach is wise.

    You need to come up with an exterior sill detail that directs water to the exterior. Since water can dribble down the rough jambs, the two most vulnerable spots are the bottom corners of the rough opening. Good luck.

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