The Sealed Attic System with. DuPont Tyvek AtticWrap INSTALLATION USING DRAPE METHOD

Transcription

1 The Sealed Attic System with TM TM DuPont Tyvek AtticWrap INSTALLATION USING DRAPE METHOD

2 Air flow Tyvek AtticWrap drapes between rafters We recommend that the first two courses of DuPont TM Tyvek be installed with DuPont TM RafterCaps when following the Drape method of installation. Refer to rafter cap steps 1-4 on pp The steps for installing the Drape method using the inset stapling technique instead of rafter caps are described in steps 1-5 on pp Where insulation comes in contact with Tyvek, rafter caps or inset stapling are necessary to prevent the air vent channels from being closed off. The Drape method requires no additional materials like furring strips or rafter caps to be installed. Tyvek is draped between rafters leaving about a 1 1 /2 in. space below the tops of the rafters. Using a jig, the Drape method can be the fastest to install; however, the eave, hip and valley details can be more time consuming than the Furring or Rafter Cap methods. When using the Drape method, extra care must be taken to prevent the attic insulation from pressing against the draped Tyvek and closing off the vent channels. This situation is most likely to occur along the exterior wall plates or anywhere insulation comes into contact with draped Tyvek. To prevent this problem, we recommend that rafter caps be installed 4 ft. up each rafter from the eave edge and in any other locations where insulation may be installed in contact with Tyvek such as above knee walls. Short pieces of rafter caps can also be installed over ridge boards, hip rafters and the ends of valley and hip jacks to prevent loose Tyvek from blocking exhaust vents. Apply the eave course of Tyvek : Snap a chalk line parallel to the eave edge approximately 12 in. to 16 in. up from the rafter tails. Roll out about 6 ft. of Tyvek with the adhesive layer at the top. Align the top edge of the membrane with the chalk line and staple the end of the sheet to the first rafter. Drape the membrane 1 /2 in. to 2 in. between rafters, using a small spacing jig to achieve a consistent drape. Staple Tyvek to the top of rafters, then inset staple the membrane to the inside edges of the rafters 1 /2 in. to 2 in. down from the top. Space staples 2 in. to 3 in. apart. Inset stapling keeps the Tyvek taut between 1 1 /2 in. to 2 in. drape depth the rafters and keeps the air vent channels from being closed off when insulation is installed. Use jig to gauge drape depth Preparation: Select the Tyvek eave detail you wish to use and install the required framing including subfacias, wall nailers, soffit blocking and rafter blocking. Complete all framing work before installing Tyvek. 2x2 13 in. long for 16 in. OC spacing, 21 in. for 24 in. OC spacing 2x3 18 in. long for 16 in. OC spacing, 26 in. for 24 in. OC spacing Build drape jig from blocks cut on the jobsite

3 STEP TWO Apply a full course of Tyvek : After completing the eaves course, begin the first full course with the bottom edge of the roll aligned with the dotted line on the course below. Staple the top corner and roll out about 6 ft. of Tyvek across the rafters. Use a multi-block spacing jig for consistent drapes between rafters and to speed the installation process (previous page). Staple Tyvek to the top of the rafters and inset staple 3 ft. in from the exterior wall. Be sure to leave the bottom 6 in. loose for sealing. Use cap nails or cap staples during windy conditions to prevent Tyvek from being blown loose. Drape Tyvek between rafters with multi-block jig Seal Tyvek layers: Lift the bottom edge of overlying course and peel the release liner from the integrated adhesive strip on the course beneath. Press the layers of Tyvek together along the integrated adhesive strip to create an airtight seal. STEP FOUR Install roof sheathing: Snap a chalk line across the Tyvek as a guide line for the top edge of the roof sheathing. Install roof sheathing following the local building code nailing schedule. Seal the layers of Tyvek together Install roof sheathing over draped Tyvek 1 /2 in. plywood strip 18 in. long x 1 1 /2 in. attached to 2x2 blocks 13 in. wide 3 ft. 2x2 STEP FIVE Drape successive courses of Tyvek : Drape the next course of Tyvek across the rafters. Align the membrane with the dotted overlap line on the previous course and fasten. Inset stapling is not necessary unless insulation will come in direct contact with the membrane. Seal the joint between layers with the integrated adhesive strip and cover with roof sheathing. Continue the sequence up to the ridge. Assemble a simple multi-block drape jig from jobsite scraps Install successive courses of Tyvek with multi-block drape jig

4 STEP SIX Wrap Tyvek over the ridge: Wrap the top course of Tyvek over the ridge and onto the other side. Seal the overlapping edge with. If the edge of the membrane overlaps less than 10 in. over the ridge, apply an additional sheet of Tyvek at least 20 in. wide over the ridge to protect this vulnerable area. Install short pieces of rafter cap over the ridge board (see pp. 13, step six) or inset staple to the ridge board to prevent loose Tyvek from blocking the ridge vent. Inset staple Tyvek to the ridgeboard and seal the overlap with Valleys can be vented two different ways. The valley rafter can be dropped by 2 in. to create a vent channel or the valley jacks can be vented laterally to an adjacent common rafter bay by applying DCI Products TM ValleyVent over the lower portion of each jack. DROPPED VALLEY RAFTER VENTING METHOD Drop valley rafter: Cut the valley rafter seat an additional 2 in. deep so the valley rafter rests lower. Use a 2 in. spacer block to gauge the valley jack installation. STEP TWO Valley dropped 2 in. to create air channel for venting jack bays Install Tyvek through valley: Cross-lap the two sheets of Tyvek meeting at the valley by 12 in. minimum. Leave enough slack in the membranes to inset staple. STEP SEVEN Leave vent slot at ridge: Rip sheathing to leave an air slot at least 1 1 /2 in. wide at the ridge to exhaust the vent channels between Tyvek and the roof sheathing. Ridge vent covers the slot and permits ventilation air to exhaust. Inset staple jack and valley rafters: Apply a 1 /8 in. to 1 /4 in. strip of wood or plastic on top of the valley rafter to hold Tyvek in position and keep the vent space open. Inset staple the membrane to the valley jacks and valley rafter. When available, install pieces of rafter caps where the valley jacks meet the valley rafter. Tape seams of the the Tyvek cross-laps with DuPont TM Tyvek Tape. Install and nail roof sheathing at ridge Apply a strip of wood or plastic on top of the valley rafter to hold Tyvek in position and keep the vent space open

5 VALLEYVENT VENTING METHOD Install Tyvek through valley: Cross lap the two sheets of Tyvek meeting at the valley by 12 in. minimum. Leave enough slack in the membranes to inset staple. HIP DRAPE METHOD Cross-lap Tyvek over the hip: Cross-lap the two sheets of Tyvek meeting at the hip by 12 in. minimum. Leave enough slack in the membranes to inset staple. STEP TWO Inset staple Tyvek to jacks and valley rafter: Inset staple Tyvek to the valley rafter and bottom 12 in. of each valley jack. When available, install pieces of rafter caps where the valley jacks meet the valley rafter instead of inset stapling. Tape the end of the Tyvek sheet to seal the joint. STEP TWO Inset staple Tyvek : Inset staple Tyvek to the hip rafter and the top 12 in. of each jack rafter. When available, install short pieces of rafter caps over the hip rafter between the jacks and at the end of the jacks instead of inset stapling. Seal Tyvek joints with DuPont TM Tyvek Tape. Inset staple Tyvek to hip and jack rafters Inset staple Tyvek to jack rafters Install ValleyVent and sheath: Apply DCI Products TM ValleyVent at the bottom of each valley jack. Position the thick (three ply) end of ValleyVent to the valley rafter and fasten it in place. Apply roof sheathing over the valley jacks and ValleyVent. Apply DCI Products TM ValleyVent at the bottom of valley jacks Install roof sheathing: Cut and install roof sheathing up to the hip. Leave a 1 1 /2 in. minimum air slot between the panel edge and the hip rafter to exhaust the vent channels. Install blocking to hip rafter to support panel edges if needed. Cut the bottom sheathing panels so the lower one foot laps over the hip rafter for support. Ridge vent will cap the vent slot and permit ventilation air to exhaust. Install sheathing at hip to create vent slot

6 Wrap Tyvek around the rafter tails and back to the wall INTAKE VENT AND EAVE SEALING DETAILS - DRAPE METHOD Install blocking and nailers before wrapping the eaves with DuPont TM Tyvek. Wrap the membrane around the eave and back to the wall. Inset staple the membrane taut between the rafter tails. Lap Tyvek over the housewrap by 6 in. and seal the joint with DuPont TM Tyvek Tape. With soffit vented eave details, clinch staple the loose Tyvek between the rafter tails to prevent air channels from being closed off. VENTING DRIP EDGE EAVE DETAIL The Venting Drip Edge Eave details use specialty slotted drip edge as an air intake Venting drip edge Blocking Leave 1 1 /2 in. space between facia and sheathing Wrap membrane over rafter, attach to blocking Leave 1 1 /2 in. space between facia and sheathing Solid soffit Venting drip edge Nailer Wrap membrane over rafter and subfacia, attach to nailer Subfacias may be installed before or after Tyvek is applied SOFFIT VENTED EAVE DETAIL The Soffit Vented Eave details use soffit vents or perforated venting soffit Standard drip edge Facia Wrap membrane over rafter, attach to blocking Continuous ventilated soffit Solid soffit Blocking For more information, Call us at: TYVEK Visit us at: Write us at: PO Box 80728, Wilmington, DE by E.I. du Pont de Nemours and Company. All rights reserved. Tyvek, The DuPont Oval Logo, The miracles of science TM and DuPont TM are registered trademarks or trademarks of E.I. du Pont de Nemours and Company or its affiliates. Standard drip edge Facia Install subfacias after Tyvek AtticWrap is applied Nailer Wrap membrane over rafter, attach to nailer Continuous ventilated soffit K14125