Continuous Air Barrier Systems - Preparing the Opening
The following section shows the recommended rough opening preparation for both air barrier and building paper scenarios where a flanged, rigid sill pan is used. Refer to the “Rough Opening
Air Barrier Applications
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| Seam | Sealant |
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| seal | |
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| tape |
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| 6″ |
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| 3/4″ |
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| Sealant |
| Rigid |
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| panning |
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(a) | (b) | (c) |
| (d) |
Figure 15: Rough opening preparation for construction methods using a continuous air barrier system and rigid sill panning.
1.Trim air barrier across top of head jamb. Trim up from the bottom corners about 2″ (51) (or half the height of the panning flange) and then make an addi- tional horizontal cut about 2 1/2″ (64) wide (or the width of the panning flange). From the horizontal cut, make two 45 degree cuts toward the center. Cut ver- tically from the head jamb to where the two 45s meet. See figure 15a.
2.Flip top flap up and tack in place temporarily. Fold sill portion to the interior and tack in place. The side flaps should be loose until rigid panning is installed. See figure 15b.
ATTENTION: Be aware that use of rigid sill pans and other barriers will decrease the rough opening height clearance. Adjust opening dimensions accordingly.
3.Run a bead of sealant approximately 3/4″ (19) from the edge of the opening. Start the bead about 6″ (152) up from the sill (or the height of the sill panning). See figure 15b.
4.Install rigid sill panning following manufacturer’s in- structions. Wrap side flaps to the interior and tack in place. Seal the horizontal cut in the air barrier with seam seal tape. See figure 15c.
5.Apply a continuous bead of sealant 3/4″ (19) from top and sides of window opening (or where casing or cas- ing flange will contact the structure). Do not apply sealant to RO bottom. See figure 15d.
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