retrofitting homes slides
TRANSCRIPT
![Page 1: Retrofitting Homes Slides](https://reader038.vdocuments.site/reader038/viewer/2022102918/54556550af795989638b6493/html5/thumbnails/1.jpg)
Seismic` Retrofitting
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The 3 Main Components of a Retrofit
1. Bolt cripple walls to foundation
2. Secure cripple walls to the floor joists
3. Install plywood shear panels
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Step 1: Bolting to Foundation
• Bolting is only of value where walls have been braced with plywood
• The number of bolts is calculated to have the same resistance capacity as the plywood
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Installed Anchoring
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Bearing Plates (Plate Washers)
Bearing plates increase strength of bolt-to-wood
connection SEAOSC Research
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Problems With Existing Bolts
• Oversized bolt holes are found in most existing bolt installations.
• More than 1/16 of an inch larger than diameter of bolt is considered oversized.
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Mudsill Splitting
• Caused by over-sized holes
• Over-sized holes are common because they allow builders to adjust the position of the mudsill
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Foundations Anchors for Crawlspaces
Foundation plates replace bolts where drill-space is unavailable
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Step 2: Secure Cripple Wall to Floor
Movement prevented by shear transfer ties
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Shear Transfer Ties Installed
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There are three ways to attach a plywood panel to the mudsill:
• Directly to Flush Framing
• The Nailed Blocking Method
• The Flush Cut Method
Step 3: Install Plywood Shear Panels
![Page 12: Retrofitting Homes Slides](https://reader038.vdocuments.site/reader038/viewer/2022102918/54556550af795989638b6493/html5/thumbnails/12.jpg)
1. Directly to Flush Framing
![Page 13: Retrofitting Homes Slides](https://reader038.vdocuments.site/reader038/viewer/2022102918/54556550af795989638b6493/html5/thumbnails/13.jpg)
2. Nailed Blocking Method
2x4 blocks installed between 2x4 studs on 2x6 mudsill
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3. Flush Cut Method
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Nailed Blocking > Wood Splitting
• Improper nailing often causes wood splitting
• Pneumatically driven staples can be driven closer and reduce splitting at time of driving and when loaded in shear
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Plywood Installation Challenge #1
Updated plumbing, wiring and structural modifications
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Plywood Installation Challenge #2
Old-fashioned, inconsistent and odd framing
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Plywood Installation Challenge #3
Replacing rotted or pest-damaged wood
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How Not to Nail Shear Panels
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The Finished Look: Cripple Walls
Shear walls with finished-to-match panels between
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The Finished Look: Crawlspace
Anchor plates and shear transfer ties house to foundation