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Questions tagged [earthquake]

Issues related to earthquake safety, bracing, or preparation.

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Can I install diagonal cross bracing with heavy tension ties on each end?

I have an existing utility building built with large (8x8) timbers. There is little, or no, shear strength in the wall diaphragms and it would be very hard to shear them with conventional plywood ...
user227963's user avatar
  • 1,078
2 votes
0 answers
142 views

What approach should I take when bolting our house to the foundation? [closed]

Our house is a four-square style over a concrete foundation, built in 1918. We're in the Pacific-Northwest, so we're thinking about hiring someone to bolt the house to the foundation in case of the ...
M -'s user avatar
  • 496
2 votes
1 answer
370 views

Why do the seismic straps need to go at least 4" above the controls on water heater?

I’m installing seismic straps on an electric water heater (48US gallon), and trying to follow the instructions. there are two general instructions: 1 - place each of the two straps in bottom and upper ...
init_js's user avatar
  • 551
5 votes
1 answer
353 views

What is the best way to drill anchor holes in a chimney?

A structural engineer who designed our earthquake retrofit instructed us to put 3/4 all-threaded-rod (ATR) through the chimney at the rafter line on either side of the chimney, back them with Simpson ...
KJ7LNW's user avatar
  • 1,205
1 vote
1 answer
294 views

Seismic Retrofit - How to decide between more L70 or less L90?

Location: San Francisco Bay Area Our house does not have a cripple wall. Plan A provides both L70 and L90 as options for floor connectors. Using L70 will require more work since we need to install ...
ssgao's user avatar
  • 155
0 votes
1 answer
138 views

Should a shear wall be strapped to a chimney?

We are seismically retrofitting our 1951 home. The chimney is in one corner of the garage and both walls abut into the chimney, but neither wall appears to be fastened to the chimney. The wall on ...
KJ7LNW's user avatar
  • 1,205
2 votes
1 answer
301 views

Do panel sheathing clips make a shear wall stronger?

In another answer it was suggested that Panel Sheathing Clips between sheathing panels in a shear wall "will add a great deal of shear resistance at a minimal cost." Is this true? If so, ...
KJ7LNW's user avatar
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2 votes
2 answers
426 views

What kind of seismic concrete hold-downs should I use for floor joists over concrete?

Our existing floor joists and decking are over an 8" concrete foundation wall. The new work pictured below extends the existing 2x4 frames for more insulation space and we want to secure the new ...
KJ7LNW's user avatar
  • 1,205
0 votes
1 answer
432 views

What is the recommended spacing for siesmic hold-down bolts for sill-plates to the foundation?

Our 1951 house has 2x4" sill plates atop of concrete. We are in seismic zone D. How frequently should the sill plate be bolted to the concrete?
KJ7LNW's user avatar
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4 votes
2 answers
1k views

What is the correct plywood/OSB orientation for building a seismic shear wall?

We are building a shear wall by adding structural-1 plywood or OSB to the existing framing and nailing according to a nailing schedule. The wall is 13'x8'. What is the best way to orient the plywood ...
KJ7LNW's user avatar
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302 views

What is the life expectancy of an earthquake safety valve?

There are many sites that recommend an earthquake safety valve to be installed on a gas line but they also sell service of installing so seems like they are just selling their service. Considering ...
simgineer's user avatar
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0 votes
1 answer
722 views

What's the best way how to seal a removed chimney top?

I want to remove a brick chimney down to the roof line because it's unused and also because it's a hazard from earthquakes in the SF bay area. This chimney came down in the 1989 quake but was rebuilt. ...
rebar's user avatar
  • 111
2 votes
0 answers
700 views

How do I brace shed walls against shear when sheathing cannot overlap rim joist?

I'm building an 8' by 13.5' shed with a loft. I posted previously about the floor frame being slightly larger than the planned floor. Below is the intended floor framing, as seen in the plan: Here is ...
fisherpeak's user avatar
3 votes
1 answer
4k views

Securing heavy steel shelving unit (sitting on floor) to walls (earthquake prep)

I'm doing earthquake preparations. I want to secure two large, heavy, freestanding shelving units that sit on the garage floor to the adjacent walls. The shelves are pretty thick steel (with particle ...
BillCord's user avatar
1 vote
1 answer
196 views

Galvanized Water Heater Straps be reused?

I've got a plumber telling me that galvanized water heater straps are one-time-use-only because they form fit to the water heater. He's saying because the new water heater isn't exactly the same ...
End Antisemitic Hate's user avatar
0 votes
2 answers
74 views

Why do foundation bolts at corners deteriorate faster?

I replaced the washers on a house's foundation bolts (replacing old round washers with larger square washers). On 6 of the ~30 bolts, the nut was rusted in place and the shaft was eroded where it ...
Phil Esra's user avatar
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1 vote
2 answers
483 views

Earthquake anchors for a standing desk

I have an IKEA adjustable standing desk I'd like to anchor to the wall in case of an earthquake. Requirements: The desk should still be adjustable, that is, I don't want to anchor it just up or just ...
Joe McMahon's user avatar
0 votes
1 answer
1k views

Do I need to add supports before replacing a cripple wall stud?

I have a section of mud sill near a crawl space entry door that has suffered severe dry rot due to rain intrusion. I need to cut out and replace about 3 feet of mud sill. This will require removal ...
MikeOnline's user avatar
0 votes
1 answer
40 views

How to find houses on types of land with less risk of damage from earthquakes?

If the general geographic location, i.e. city or metro area is fixed, what methods and data sources should I use to know what land areas in the region have less risk of damage to houses from ...
qazwsx's user avatar
  • 155
1 vote
3 answers
20k views

How do I secure an open-backed set of shelves to the wall?

I read this guide on how to anchor furniture to a wall but it assumes that you’ll need to drill through the back of the item, attach something to the inside, and connect this to the wall. I have a ...
bdesham's user avatar
  • 111
0 votes
0 answers
46 views

Is this foundation properly supported against rotation in an earthquake?

This foundation was built 1938, and seems unusually tippy even for the time. This is in an earthquake zone, the garage has a second floor above, and the given wall is shearwalled and bolted, with ...
Bryce's user avatar
  • 10.9k
0 votes
1 answer
211 views

How do I secure this post to the structure to protect against seismic damage?

My foundation is attached to the frame of my house using seismic brackets, and I live in a earthquake-prone area. I noticed I have 3 posts that hold up my center of my house that seem to only be ...
John's user avatar
  • 838
15 votes
5 answers
62k views

How do I tell if my house is brick or brick veneer?

I live in a brick house, and am interested in understanding whether it is brick or brick veneer, as a way to understand what kind of risks it (and we) may face during an earthquake. I hear that brick ...
John's user avatar
  • 838
3 votes
1 answer
1k views

Proper backfill for a trench dug below foundation level (within the 45 degree cone of support)

Given a trench dug below foundation level, what's the proper way to backfill? Here I'm talking about a trench below the bottom edge of an unreinforced concrete foundation built in 1950, supporting a ...
Bryce's user avatar
  • 10.9k
1 vote
2 answers
12k views

Trying to secure a 100lbs floor mirror so it doesn't tilt over. is it possible to do this without a stud?

This wall is not shared by another tenant directly next door but does have a unit above me. I cannot find a stud. i have used a magnet stud finder. I have nailed a 2.5" nail into the wall in 1 inch ...
Regi's user avatar
  • 11
3 votes
2 answers
3k views

Are there span tables published for repairing a cut roof joist?

A roofing company mistakenly cut a 2 foot section out of a roof joist, on my home. I'm seeking a reference to what would constitute a proper repair, preferably a prescriptive code or a load table. ...
Bryce's user avatar
  • 10.9k