R-Guard Installation Detail

Interior Air and Water Seal

CMU/cast-in-place concrete wall construction

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If wood bucks are not already installed, apply FastFlash or Joint & Seam Filler along the perimeter faces of the wood bucks before attaching to the structure while still wet. Install anchor bolts to secure the wood bucks into the opening. Tapcons/anchor holes should be pre-drilled and blown out with oil-free air in preparation to receive a shot of FastFlash or Joint & Seam Filler into the hole prior to inserting tapcon/anchor.


If the pre-treated Wood buck is already installed, pre-wipe the wood buck with isopropyl alcohol and apply FastFlash or Joint & Seam Filler in each corner and in a zigzag pattern over the inside the concrete block rough opening. Use a dry spatula, trowel or chipper brush to spread the wet product to protect the rough opening CMU surface. Apply additional FastFlash or Joint & Seam Filler as needed to create an opaque, monolithic flashing membrane free of voids or pinholes. Allow membrane to skin over.



After installation of wood buck, spot and cover the installed head of the anchor bolts.



Apply FastFlash or Joint & Seam Filler to the perimeter joint between the wood buck and CMU wall. Use a dry spatula or trowel to seal the joint. Create a profile that directs bulk water away from the joint. Allow FastFlash or Joint & Seam Filler to skim over. Apply FastFlash over the inside of the wood buck, extending the membrane out to the edge of the return opening when used for window protection only. When used in conjunction w/an entire air/moisture barrier system, carry the FastFlash out on to the face of the vertical wall a minimum of 4 inches to facilitate a tie in to an air barrier system.

Ted Barnekoff - Air & Water Barriers, PROSOCO

Ted Barnekoff
Product Support - Air & Water Barriers


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