Strong Built Establishments Builders

SBE Builders is a commercial and residential framing contractor located in Discovery Bay California. Dedicated to the art of Carpentery & Roof Framing. We are the professionals for the future of the craft of carpentry.

Structural Shear Wall Panel Construction variables:

How well is the wall put together? All of our framing is tight and secured at each end with a structurally engineered hold-down unless U.O.N. on the structural plans.

Are there nails missing? All of our structural shear walls are marked off at the structural engineers' required nailing pattern for the allowable shear force in pounds per foot. 6-12 : 4:12 : 3:12 : 2:12 The marks on the structural shear wall plywood panel help us precisely place the nails at the correct nailing pattern resulting in the correct number of nails per sheet. With the correct number of nails per sheet the allowable shear force in pounds per foot for wood structural panels is archived.

Are nails hitting the studs correctly? All of our structural shear wall plywood panels have caulk lines centered on each stud for precise nailing, eliminating shiners.

Are nails overdriven? We use nails guns with positive placement fittings to ensure the nails are set at the correct depth. If the nail is over driven, more than 1/32" below the surface of the panel, due to a soft spot in the plywood we drive another nail next to the over driven nail.

Are there gaps in the sheathing? We use an 1/8" gap at all panel edges to reduce plywood panel edge swelling per the APA. We use an 1/4" gap at all 4'x10' panel edges to reduce plywood panel edge swelling per the APA.

Are the nails penetrating the framing members correctly? We use a minimum of an 2 3/8" gun nails that result in a minimum of 1 5/8" nail penetration into the wood framing member, which is also the UBC & CBC code minimum requirements in Table 23-II-1-1 for allowable shear force in pounds per foot. We do not use 10D shorts, 2 1/8" x .148. The 10D shorts have been tested by the University of California - Irvine and other structural engineers and have shown nails exhibited about 5% less maximum shear load due to nails withdrawing from the framing under cyclic loading.

Are the nails the correct type and diameter? We use hot dipped galvanized gun nails that result in better nail gripping power and don't rust out, U.O.N. on the structural plans. All of our shear walls and wall bracing panels nails are 10d x .148, that results in better nail gripping power and do not withdraw from the framing under cyclic loading like the .131 8d nails do. The 10d x .148 also have less fastener fatigue failures under cyclic loading.

Are shear wall panels the correct type of plywood or OSB? All of our structural shear wall plywood panels are CDX Douglas fir-larch APA rated sheathing Struct 1 Group 1 with a span rating of 32/16 unless U.O.N. on the structural plans. If the structural plans call-out Struct 2 we will still use 5 ply CDX at a minimum. We don't use OSB for shear walls because of the swelling and nail popping associated with OSB plywood. There are earlier and more extensive fastener fatigue failures in the cyclic load shear wall tests with OSB than with CDX plywood. This is due to higher density strength in OSB than CDX plywood. It is theorized that denser OSB sheathing deforms less along the nail shank in contact with the sheathing, creating a "fixed end" condition on the fastener. As a result, higher internal bending stresses in the nail shank may develop at locations below the surface of the wood framing, thus causing earlier fatigue failures of the fasteners under cyclic loading. If the fasteners don't fail than there's more potential of panel edge tear out with OSB.

Are the allowable shear force in pounds per foot for wood structural panels archived? Yes, all of our structural shear wall panels archive the code minimum requirements in Table 23-II-1-1 for allowable shear force in pounds per foot. By using Struct 1 plywood and 10d nails our wood structural panels meet the allowable shear force in pounds per foot. .

Pressure Treated Sill Plate variables:

What type of pressure treated sill plates do we use? All of our pressure treated sill plates are Pac-Bor borate .42 without NaSiO2. By using Built It Green recommend Pac-Bor borate .42 the nails in the sill plates still need to be hot dipped galvanized (g185) but the anchor bolts and hold-down bolts do not need to be hot dipped galvanized. However, it wouldn't hurt if they were hot dipped galvanized.

Pressure Treated Sill Plates test by Simpson StrongTie:

• ACQ-D (Carbonate), CA-B, and SBX (DOT) with NaSiO2 treated wood is on the average approximately two times more corrosive than CCA-C treated wood. Note that the standard galvanized coating for years on Simpson connectors was G60 which has proven over time to perform well on CCA-C wood. Thus, it could be reasoned that there needs to be at least two times the coating protection when used in conjunction with the tested ACQ-D (Carbonate), CA-B, and SBX (DOT) with NaSI02 treatments. Thus, it is Simpson’s recommendation that at a minimum a ZMAX™ coating, which provides approximately 3 times the corrosion protection of G60, should be applied to meet the potential demand from these treated woods.
  
• Testing on Sodium Borate (DOT-Disodium Octaborate Tetrahydrate) treated wood generally indicates corrosion rates less than seen with CCA-C treated wood.