Shear bracing the knee wall

Lee is putting shear bracing back into the house. This will help if the “big” earthquake that has been forecasted for Oregon actually happens, but also just makes the house sturdier. Lee has some plans on making our old house more earthquake ready along the way. This is one of them.

Today’s project was the knee wall: a 5 foot high wall that forms two sides of the second floor and supports the roof. Our knee walls all sit on beams that span open living space below. The plan is to add OSB panels using adhesives and nails which will permanently tie the beams and knee walls together. This does two things. It adds shear, to resist lateral forces from wind and earthquakes. It also creates a connected load path, to prevent an uplift earthquake from breaking the knee walls loose.

To start off, Lee jacked up the widest span by 1/4″ before adding bracing. This heads off future sagging.

The beam is slightly narrower than the knee wall, so he added 3/8″ plywood shims to create a coplanar surface. 8″ wide strips of plywood were glued to the beam using construction adhesive and attached with a few nails.

Once that was on, Lee applied polyurethane construction adhesive to the beam and 3.5′ up the knee wall studs for each 8′ sheet of OSB.

The OSB was lifted into place and attached using 2.5″ ring shank nails. Rink shank nails have tiny one-way barbs that make them easy to drive but hard to remove. A shear wall nailing schedule was used, with nails placed about every 4 to 5 inches.

Lee decided that he wanted more bracing, so he added 2′ strips of OSB at the top of the knee wall. The seams were staggered for greater rigidity.

Finally we sheeted more ceiling area in with plastic to help slow down the heat loss until we can get around to real insulation. Yes, that is a saw in my living room. I sure don’t miss Arizona, but I do miss my nicely put together house. I think the plastic ceiling complements my plastic curtains.

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One Response to Shear bracing the knee wall

  1. Pingback: Nailing up sheathing » Farm Folly

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