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Window and Outer Flashing

 

Launch Slideshow

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Flashing and Trimming a Window

Setting the window and applying the outer flashing

Flashing and Trimming a Window

Setting the window and applying the outer flashing

  • Figure 6. A bead of caulk on the top and sides of the flashed opening provides a bed for the windows nailing flanges (left). Once pressed into the caulk, the window is plumbed, leveled, and fastened in place (above).

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    Figure 6. A bead of caulk on the top and sides of the flashed opening provides a bed for the windows nailing flanges (left). Once pressed into the caulk, the window is plumbed, leveled, and fastened in place (above).

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    Emanuel Silva

    Apply beads of caulk on the top and sides of the flashed opening to provide a bed for the window’s nailing flanges.

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    Emanuel Silva

    Set the window into the opening and press the flanges onto the caulk. Plumb, level, and fasten the window in place.

  • Figure 7. Outer flashing goes on over the windows side and top flanges (A, B). The flap of housewrap above the window head is then pulled down and taped in place over the head flashing (C, D).

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    Figure 7. Outer flashing goes on over the windows side and top flanges (A, B). The flap of housewrap above the window head is then pulled down and taped in place over the head flashing (C, D).

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    Emanuel Silva

    Apply membrane over the window’s side and top flanges to create an outer flashing.

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    Emanuel Silva

    Pull the flap of housewrap above the window head down and tape it in place over the head flashing.

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    Emanuel Silva

    Fasten and seal the housewrap flap with tape.

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    Emanuel Silva

    The window flashing is complete.

Before placing the window, I caulk the top and sides of the flashed opening to provide a bed for the flanges (see slideshow). I don’t caulk the area behind the bottom flange, though — that way, water can drain to the outside if necessary. For added insurance, I apply a continuous bead of caulk to the horizontal surface of the sill, about 2 inches in from the sheathing. This acts as a dam to prevent wind-driven rain from penetrating beyond it.

After installing the window and confirming that it’s plumb and level, I nail it in place according to the manufacturer’s directions.

Once the window is secure in the opening and operating freely, I’m ready to apply the outer flashings. I install the side pieces first, working from the top edge of the inner head flashing to the sill, then I go back to the top and add the head flashing. Finally, I pull down the folded strip of housewrap at the top and seal the corner cuts with strips of housewrap tape. I don’t tape the bottom of the housewrap, so that any water that penetrates the housewrap can drain rather than soaking into the sheathing.