*
Hey-
My 2 bits worth in regards to Chimneys. I was born in S.F. and was working in the masonry trade during the 89 earthquake. I have photos of the Marina Neighborhood after the fact, as I lived several blocks away at the time. I currently reside in Santa Cruz, not far from the epicenter of the Loma Prieta ’89 quake. Ironically I now am in business specializing in chimney repairs and rebuilds. As G. Wheeler pointed out, the chimneys are in fact reinforced with 4 rods of vertical steel,(the size may vary from city to city but generally 1/2″ is suffice). The U.B.C. requires “pencil-rod” or 1/4″ stirrups , I believe every 16″ but I prefer every 12″, simply because I am in the habit of laying them in to the mortar bed each time I add a flue tile. The strapping Gary is referring to is known as FHA strapping. They come in 4′ and 6′ lengths an wrap around the outer rebar rods, and are through bolted using 1/2″ carriage bolts to 2’x4’x8′ studs fastened in the attic crawl space to the ceiling rafters with 2- 16 sinkers every 16″. Note the straps must be installed at every story or if the space from finished ceiling to roof-line is greater then 4′, some cities will require a second set of straps. As we move towards topping out, the stack wants to be 2′ higher then the nearest peak within 10′, and should the stack extend more then 6′ above the roofline, a “T” brace is required, which opens up a whole new can of worms ie. engineers reports, roofing issues and mechanical inspections. The long of the short is, California as a result of the 89 quake, has tightened up its standards for reinforcing masonry chimneys, to the point where some cities’ permit departments discourage rebuilding in masonry, and favor instead the class A or metal solid pack flue systems.
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I'm visiting family and friends in the S.F. area, miraculously timing my trip to avoid the misery back East.
I visited a friend's 1960's post-and-beam house a few days ago to poke around. I marveled at the extravagant use of wood -- the post were around 6x12, the balcony was decked with cedar 2x4's on edge, etc.
My question is SEISMIC: what sort of post-beam connection is considered appropriate?? The posts in question rise about 12' from bedrock through a garage to the beams, some of which are spliced over the posts. The connectors looked to be of the Simpson-type guage connectors -- but quite large -- with nails. Is this enough? I'd've expected bolts and heavy angles...
*Welcome to the best coast. If you plan on visiting Hearst Castle, let me know because I'm only 7 miles south. I can only answer one of your questions..."is it enough?" The empirical evidence suggests that, yes, it is enough. Since the 60's, there have been a few large quakes sufficent to rattle your friend's house. The connections you describe are fairly common. However, usually they use bolts, not nails. Also, there are also the "gang nail" plates used commonly. They are perforated so a sharp prongs is formed which is driven into the wood. These also feature a nail schedule for 16d.Before Simpson, before "gang nails", the guys got pretty creative. Although 1960 is not that old.
*"Best" coast? Hmm. Just hoping to get going before the ground shakes ... I barely missed the one in '89 (?) that did in the Marina. Funny, I grew up here, nearly 16 years, and never saw anything more than a window-rattler. More recently it has been a bit more ... active.My question was mostly a point of curiosity -- I know nothing about hurricane/seismic precautions. It seems to me the point is to keep things attached as they wiggle and sway. I'm not sure how masonry chimneys are supposed to survive tho'.We'll be in your neighborhood one of these days, friends in N&S CA. My wife and I visited the Castle on our honeymoon. California, a great place to visit but... Hey, I'm not complaining, our son is our wonderful souvenier.
*Masonry chimneys have vertical rebar in the space in the corners between the flue liner and the brick. Horizontal rebar ties every 30" or something like that, and a steel strap going around the rebar and tied to the ceiling joists.That's probably why most new chimneys are premanufactured metal units instead.Good seismic engineering is invisible. Holdowns, steel straps, rebar and plywood shear walls are invisible once installed.Some of the older freeway bridges have steel cable and bolting plates visible, as they were retrofitted, but that's the exception.I've got a link to a current earthquake map on my personal web page. Sort of like checking the weather out here, but not much has been happening here for years. http://home.att.net/~g.wheelerGary Wheeler, AIA, Modesto, CA
*Hey- My 2 bits worth in regards to Chimneys. I was born in S.F. and was working in the masonry trade during the 89 earthquake. I have photos of the Marina Neighborhood after the fact, as I lived several blocks away at the time. I currently reside in Santa Cruz, not far from the epicenter of the Loma Prieta '89 quake. Ironically I now am in business specializing in chimney repairs and rebuilds. As G. Wheeler pointed out, the chimneys are in fact reinforced with 4 rods of vertical steel,(the size may vary from city to city but generally 1/2" is suffice). The U.B.C. requires "pencil-rod" or 1/4" stirrups , I believe every 16" but I prefer every 12", simply because I am in the habit of laying them in to the mortar bed each time I add a flue tile. The strapping Gary is referring to is known as FHA strapping. They come in 4' and 6' lengths an wrap around the outer rebar rods, and are through bolted using 1/2" carriage bolts to 2'x4'x8' studs fastened in the attic crawl space to the ceiling rafters with 2- 16 sinkers every 16". Note the straps must be installed at every story or if the space from finished ceiling to roof-line is greater then 4', some cities will require a second set of straps. As we move towards topping out, the stack wants to be 2' higher then the nearest peak within 10', and should the stack extend more then 6' above the roofline, a "T" brace is required, which opens up a whole new can of worms ie. engineers reports, roofing issues and mechanical inspections. The long of the short is, California as a result of the 89 quake, has tightened up its standards for reinforcing masonry chimneys, to the point where some cities' permit departments discourage rebuilding in masonry, and favor instead the class A or metal solid pack flue systems.