Is there a difference in shear capacity between plywood and OSB panels of the same thickness?
There is the racking shear capacity (also shear wall capacity) that is in SPDWS, which is treated the same for OSB and plywood. For more information, consult Table 23 of the Engineered Wood Construction Guide, Form E30.
For both shear-through-thickness and planar (also called rolling) shear there is a difference in shear capacities between plywood and OSB. Table 8 of the Panel Design Specification, Form D510, shows the shear design capacities between plywood and OSB with respect to span ratings for panels installed both parallel and perpendicular to the strength axis.
In all applications, are the clips required for roof sheathing, and do they provide the 1/8" gap?
Most builders install them, but they are not automatically required for all applications. Most, but not all, panel edge clips provide the 1/8" gap. Table R503.2.1.1(1) of the International Residential Code (IRC) and Table 33 of the Engineered Wood Construction Guide, Form E30, provide guidance.
How long can Exposure 1 panels stay wet, or how long can they be exposed?
Please refer to page 13 of the Engineered Wood Construction Guide, Form E30, and Technical Topics: Moisture Exposure Recommendations for Wood Structural Panels, Form TT-002, for more information.
Is CDX plywood rated for exterior use?
CDX is discussed on page 13 of the Engineered Wood Construction Guide, Form E30.
What about bracing for seismic and wind?
APA has a free five-part webinar series on wall bracing that is available online for on demand viewing > Wall Bracing Webinar Series
I often see trusses being stored in a laid position and bent due to weathering. Are these still suitable for construction?
Trusses are outside of the scope of APA; however, it is important to ensure that they are aligned and straight at the time of installation to provide a level nailing surface for sheathing. Get storage guidance for engineered wood products >
Should moisture content of framing materials be field-tested before enclosing with cover materials?
It’s difficult to test every inch of material with a moisture meter, and it is difficult to get an accurate moisture reading of wood material due to the multitude of variations in not only the testing equipment and its use (e.g., calibration, meter drift), but also in the wood itself. Once a structure is complete, wood normally stabilizes to an in-service moisture content between 6 and 14%. At these low levels, moisture has negligible impact on strength, stiffness or durability. However, accumulated moisture can lead to decay and mold growth if it remains greater than 20% for a prolonged period.
Does installing spray foam into the 1/8" gap between wall sheathing panels restrict the panel expansion?
Installing anything in the gap, including spray foam, could prevent the expansion of the panel. The 1/8" gap is intended for the panel to expand and does not need to be filled.
APA recommends tack-nailing a panel to allow it to acclimate before completing a tight nailing pattern. How long should the panel be allowed to acclimate before the nailing can be completed?
Please refer to page 13 of the Engineered Wood Construction Guide, Form E30, Technical Note: Minimizing Buckling of Wood Structural Panels, Form D481, or Technical Topics: Moisture Exposure Recommendations for Wood Structural Panels, Form TT-002, for more information.
Since there is a recommended 1/8" spacing, are panels manufactured with that spacing taken into consideration (e.g., 3' 11-7/8" by 7' 11-7/8")?
Technical Topics: Sized for Spacing, Form TT-055, provides more information on panel manufacturers’ ability to manufacture panels to a size slightly less than the traditional nominal sizes.
What materials are suitable for squash blocks?
Dimension lumber, pieces of APA Rim Board® or APA Rated Sturd-I-Floor are all listed as acceptable materials in Builder Tips: I-Joist Squash Blocks, Form A755.
What do I do if my plumber or electrical contractor punched a large hole in an I-joist? How do I know if it is okay? Where do I find repair details?
Page 24 of Performance Rated I-Joist Design and Construction Guide, Form Z725, provides some general guidance for holes in I-joist webs. When in doubt, contact your I-joist supplier or the manufacturer’s website. Keep in mind that flanges of I-joists should never be drilled, cut or notched.
Does I-joist floor construction require fire protection over a basement area?
Yes. Learn more and see several options for fire protection of I-joist floors with our recorded webinar (scroll down page) > I-Joist Fire Assemblies
What about building a short wall out of dimension lumber as a rim joist for I-joists?
A qualified design professional should review the detail. Building a short wall out of dimensional lumber and wood structural panels might meet these needs, but the details in Performance Rated I-Joist Design and Construction Guide, Form Z725, are preferred.
Why can’t we mix sawn lumber with engineered wood, e.g., a sawn lumber rim joist with engineered I-joists? A standard strengthening detail for sawn lumber is to sister them. Is this a situation where engineered wood and sawn lumber could be mixed?
APA does not recommend mixing sawn lumber with engineered wood products. APA’s Technical Topics: Wood I-Joists and APA Performance Rated Rim Boards, Form TT-022, provides more information.
Can you use staples instead of nails?
Yes, staples can be used instead of nails. The International Building Code (IBC) and International Residential Code (IRC) specify requirements for sheathing fasteners including staples. There is a table that specifies fasteners, and for staples, it permits wire staples with a minimum 7/16" diameter crown. Also, it is important to note that staples should be installed with the crown parallel to the support below. This helps ensure that both legs of the staple get good embedment into the support.
For more specifications on staples and other power-driven fasteners, contact the International Staple, Nail and Tool Association (ISANTA).