SILCOR® 900HA/900MP Waterproofing Plywood Substrates Technical Bulletin
- Use plywood panels meeting the American Plywood Association (APA) Exposure 1 or exterior exposure durability classification. According to the APA, Exterior 1 panels are designed for applications where long construction delays may be expected prior to providing protection, or where high moisture conditions may be encountered in service.
- Use plywood panels with B-grade or better veneer to minimize surface preparation.
- Apply Plywood according to building code requirements and APA recommendations. APA recommendations are outlined in the APA’s Design/Construction Guide: Residential &Commercial, Form E30.
- Plywood must be installed per manufacture’s requirements and fully supported at all butt joints with blocking between joists.
- Joints in plywood panels should be minimized and butt joint spacing must comply with manufacturer’s requirements.
- Ensure the assembly is adequately vented if applicable and complies with all building code requirements.
- Oriented Strand Board (OSB) is not an acceptable substrate for SILCOR® applications.
- Substrate must be clean, dry and free of dust and other contaminants.
- All horizontal joints between plywood panels must be filled flush with a Polyurethane Sealant and allowed a min. 24-hours to cure.
- All vertical upturns, inside corners, deck to wall junctions must receive a fillet of BITUTHENE® Liquid Membrane.
- Apply SILCOR® EPS or EPF Primer to the horizontal and vertical plywood, Polyurethane Sealant and BITUTHENE® Liquid Membrane per the applicable data sheets/installation instructions.
- Allow SILCOR® Primer to cure to a tack free condition.
- When SILCOR® Primer is tack free, install a 2” wide self-adhesive bond-breaker tape over each horizontal plywood joint. (Do not install bond-breaker tape at deck to wall junctions or over the fillet of BITUTHENE® Liquid Membrane.
Silcor 900HA/900MP Application:
- Apply SILCOR® 900HA/900MP within 24-hours of the SILCOR® Primer application at a minimum thickness of 80-mils per applicable data sheets/installation instructions.
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Last Updated: 2022-05-16