what would be the expected cost, per bolt, on a seimic retrofit (bay area CA). Would use 5/8 inch x 8 inch threaded rod epoxyed in place with upgraded square steel washer. Good crawl space access and sill plate is generally reachable from a vertical position using rotary hammer drill. Also how much add’l for 90 degree hold downs if used say every 8 feet?
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Questions.
Is this an engineered retrofit or standard details? Will it be inspected? Do you need an inspector on site to observe the placement of the epoxy?
I would guess at least 1/2 labor per bolt. Look into using a Titen HD instead of an epoxied anchor.
Hold downs are required at the boundries of shear panels. Just putting a hold down every 8' would probably be a waste. If you're just looking to hold down the cripple wall with no openings, a properly engineered hold down at each end should do. The cost would be considerably more if you have to retrofit the cripple walls or the walls above. You'd probably need at least 4x boundry members The cripple walls could probably be shear panelled from the inside. You need to be sure the foundation is adequate.
god feedback- not inspected as I'm just ballparking a friend's quote for bolting and no shear wall.
If there's no shear wall, then you don't need hold downs. Think about the Titens. 5/8" x 8"
i've seen them at building supply stores and they look as if they would save time on installation. Hard to believe that with no epoxy to bind them into the drilled hole that they would stay in place with no glue, and no square washer during the next anticipated 7.0 on the Hayward fault. But I'll give them another look...
The specs on them are suprising. But don't omit the square washer.
If there's room for a hammer drill then I'd allow an hour per hole to account for figuring out where to drill, the 10 minutes to drill the hole, and other time dinking around required to get it epoxied and tightened down. On my own remodel I'd allow 30 minutes per since all the thinking as already been done.
If there isn't good clearance for a hammer drill it might take 4 hours per hole or longer. In those cases there are better options using various brackets to move the angle or placement of the hole and still accomplish the same thing.
There are so many unknowns with retrofits that any bid is goiing to be high to cover the unexpected, or it has so many exceptions/add ons that it turns into a bottomless money pit. The last expoxied hold down I drilled for had 8" of slab before the stemwall and at 10" hit a big pocket of dirt. Luckily I was allowed by the engineer to move the location and drill at an angle into a different section of stemwall and bend the allthread verticle. Nope, something so simple is never all that simple with old houses.