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Joined: Apr 2002
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Greg: Thanks for the nice detail pics. Pics say a 1000 words. The 'green' rebar is the ufer, and that is green spray paint, correct.
Green rebar up here is epoxy coated to slow corrosion.
John
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Joined: Jan 2005
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Those are some interesting pics. Greg. I've never seen a block wall made in quite that manner.
I wasn't so clear about block vs. concrete. I haven't seen many concrete walls.
The 'block wall' I am most familiar with - a style seen in Illinois, Nevada, and Arkansas, so forgive me for thinking it was the common method - starts with a concrete slab. Or, at least, a concrete footer.
There will be rather short bits of rebar either poking out of this concrete in select locations.. These pieces are likely to be either 3/4" or 1/2" rebar; 5/8" just isn't commonly used. You usually START with a copper wire set in this concrete for the Ufer.
The rebar is run vertically in only a few select locations, usually near corners and doors. Most often, the block is not the primary structure; there's proper steel for that. Block only fills the spaces between the columns.
Usually there are only a few courses of block where rebar is run horizontally. Bottom, top, and one somewhere above the half-way mark seems to be the practice. This rebar is a lot smaller, perhaps 1/2". It's pretty much just laid in a groove that is manufactured into the blocks, tied to the verticals and each other, and buried in mortar.
Windows and doors have a piece of steel- often angle iron- used as a header. (Not always; I've seen 8-ft. garage door spans made without anything but filled block, not even rebar to tie it all together).
That brings up another relevant point: TIME. Whatever is being done today, you can't expect that to have been the way they did it even last year ... let alone during our childhood. There have been major changes. The excuse varies (hurricanes, earthquakes, whatever), but the result is the same .... there's no telling what you'll find.
The rebar generally doesn't sit plumb and level within the block - especially where pieces overlap. It's often bent or tilted. The result is that you can miss the rebar completely in your first three holes, then run into it on the fourth. You need not run into it by much ... just 1/8" of contact is enough to catch your bit or stop your core drill.
(That's right ... I generally use core drills for everything larger than 1/2")
So, punching a hole in block is a crapshoot ... you either have the hole made in a heartbeat .... or it takes half a day. The difference? Rebar. That's why I'm looking for a better way to deal with rebar.
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Joined: Jul 2004
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I don't work in the field. A friend who worked in broadcast radio made the comment about a building he worked in, that had a high power FM transmitter in the building. He stated he could follow ANY piece of metal pipe in the building by using a little transistor radio.
I wonder if that effect could be used to trace rebar in a wall by hooking a little 15 W transmitter to the accessible rebar and tracing the metal. Something similar to a pair finder tracer.
Larry
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Joined: Jul 2004
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There are 2 styles of wall here. One uses a "U" shaped lentil block over doors and windows that gets 2 #5s and then a course of block with the "U" cut out at the top for the second pair of #5s. These 2 courses are poured solid along with the doweled cells. The other method starts with the block built up to the top of the windows and doors and the whole top 16" is one solid pour. "hooks" #5s with a 1' bend at the top are tied to the tie beam steel and go down in the doweled cell where it gets tied to the ones coming up. That is the way this one was done. John, yes the green one is the Ufer. a #4 copper wire tends to be gone before they get ready to set the panel. There is always a fight about whether it is legal since it is not "encased" in concrete. If they really insist, that core gets poured solid after the acorn and #4 goes on. The paint is marking paint and the rain will wash it off before they finish the wall most of the time. If not, they wash it off.
Greg Fretwell
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Joined: Dec 2002
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Its interesting to see the different building techniques used in various places. There is a huge variation between North and South of Europe, reflecting climate differences, and in some places earthquake risks. I am sure the same must apply across the States.
The last two pictures resemble to me methods I've seen in the South of France in a relative's new house. Single hollow block walls with some re-bar and a poured concrete "top" which I was told was an earthquake safeguard. In UK the norm is double,(i.e. cavity) walls with insulation between the layers, making an outside wall 12 inches thick
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Joined: Jul 2004
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Florida leads the world in hurricane resistant construction and Miami Dade is the leader here. The problem with (hurricane) Andrew was not that the code was weak. It was that the inspections were weak to non existent out in the unincorporated county. There was a big shakeup in Dade county, merging it with Miami but the biggest difference was a change in the whole building code system in Florida. We now have a uniform building code state wide and state licensed building code officials. They also beef up the code just about every cycle. One thing you don't see here is houses knocked off the foundation and floating away. You also do not see the roof coming off. You might lose the shingles but the structure will still be there. Our latest wind code map has most of the southern peninsula with a 140MPH or above rating and it is 180 down in the keys.
Greg Fretwell
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Joined: Apr 2002
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Greg: Thanks for all the info. I've only seen one (1) SFD that was built similar to what is in your pics. It has been 2-1/2 years in 'progress'.
John
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Joined: Jul 2004
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My wife was banging them out, 2000-3500 sq/ft, in 12 to 16 weeks. The cycle time was 16 weeks but if the bonus was right she could shorten up that time frame The 12 week house netted her a $8k bonus.
Greg Fretwell
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Tom
Shinnston, WV USA
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Joined: January 2001
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