Vinyl Windows with T-111 Siding

Robert asked

I want to build a shed using vinyl windows with T-111 siding.   There is no other sheathing under the siding so how should I frame the window openings so the windows don’t leak and how do I cover up the nailing flange on the windows

 Robert,

There are several methods of installing vinyl windows with T-111 siding.  One of the simplest and most maintenance free methods is to utilize vinyl brick mold to seal and

Vinyl brick mold

vinyl window without J-channel

cover the nail flange.  I recommend using  vinyl windows that do not have built in J-channel.  If it does have a built in J-channel extra care must be exercised to ensure a good seal between the J-channel and the vinyl brick molding.

• Frame window opening to the rough opening size recommended by the window manufacturer
• Install T-111 siding with window openings cut out to the same size as framing
• Wrap jamb with plastic vapor barrier that covers framing and extends about 3 or 4 inches onto the t-111
• Apply a liberal bead of caulk on the window wrap all the way around the window opening
• Set the window in the opening ensuring that the caulking seals the window flange to the wrap on all sides and nail the window in place
• Apply a continuous bead of caulk on the face of the nailing flange centered over the nails/nail slots and another bead on the adjacent side of the window jamb
• Cover the nailing flange by installing vinyl brick molding around all four sides of the vinyl window in a “picture frame” configuration
• Use PVC glue or adhesive caulking on the corner miters to prevent water infiltration
• Caulk the exterior of the brick mold to seal it to the siding/window wrap with special emphasis on the top
• For increased weather protection install a metal or vinyl drip cap over the window

This method will make the window installation watertight, mostly maintenance free and allow for replacement of the window if needed without having to disrupt the siding.   Routine maintenance such as caulking and painting will extend the life of the shed indefinitely.

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