Anchor bolts in new concrete

[youngins]

Do anchor bolts move/settle during the curing process?

What is the trick to prevent them from getting "bumped" out of position?

[glenn kangiser]

They don't move after the concrete sets-major portion of the curing process takes 28 days and usually 7 days is minimum to begin working with placed anchors - many do it after 1 day or more  in non-critical applications, but when wet - yes - they can sink.  

I usually make wood or steel templates with proper spacing and nail them to the forms or make a support structure out of 2x4's or plywood.

Inaccurate spacing is a real pain - make your templates accurately.  Not as big a problem with wood but with steel columns it creates real problems.  Also be sure to leave enough sticking above the concrete.

New practice for many engineers now is to use machine bolts with normal hex heads for anchors rather than J bolts.  They say the J bolts can straight and pull out under bad conditions where the standard hex head bolt will hang up on the concrete and not pull out.  This is also more critical for steel than wood.

[PEG688]

 What Glenn said is true , mostly

 Yes they can settle , if your mud is very thin , as in a poor mix of bagged redi mix , or if say you get your mud on the back side of someone else's pour , and that mud was say run into a pump truck then spit back into the mixer truck , they add a lot of water when that happens to clean the pump trucks pump.

 But in a normal mixer pour by the time you finish up , and start to screed off the cement to your snapped line or row of nails your pouring to ( seldom is the top of the form the "exact top" of the concrete) the mud will be starting to kick , you should have your "J" bolts on site , and you should know what lenght plate stock you'll be ordering / using .  Most folks use a 2x6 PT plate , most walls for one storey house's are 6" wide , so placement side to side is not as inportant as lenght placement. Start in a corner and place a bolt 12" in from the end , leaving 2" sticking out / up generally the threads are about 2" on most J bolts , you'll need two bolts  2' apart at every joint in the plate stock , as each plate is suppost to have a bolt within 12" of the end , so a 2' piece of plate stock should have 2 ea bolts in it.

 Like Glenn said in steel templates are inportant , in wood not so .

BTW  I've never heard the hex bolt deal Glenn was talking about , IF a situation , earth quake , hurricane / tornado come s along and pulls 10" J bolts out of concrete by straighting the 1/2" bolt out what ever was there will be gone , talk about over building   over engineering   Hoy Vey!!

Good luck PEG

[glenn kangiser]

See, PEG --- that's the problem when a steel guy answers a wood question -- he makes it a lot harder than it needs to be.  

I agree that the anchors will not settle in a proper concrete mix --- providing that someone doesn't kick them or bump them or step on them.  A recheck while it is still soft enough to rework is always a good idea, and even then if one gets messed up its not the end of the world.  I guess that's what they made rotohammers and epoxy , or expansion anchors for. :-/

[PEG688]

I like these for anchor bolts when one is misplaced / left out .

 

Link : http://www.simpsonanchors.com/catalog/mechanical/titen-hd/index.html

You do need a impact driver to drive them in !

[glenn kangiser]

Now you went and showed me something I didn't know again, PEG.   :-/  I may need some of those. :-?

Expensive?

I saw them in use on a job once but I thought they were something special for tilt-ups.  

[PEG688]

 Nah not when you consider the speed factor in over a Hilti bolt or a epoxy kit , mixing , cost of gathering threaded rod , etc. Quick clean easy , with a impact of course , you'd need a 4' cheater bar on a great socket other wise and then maybe you couldn't drive one.

I have found some water in the hole helps to drive them and over boring for depth by a couple of inchs , if possible , clears out the hole.

So ya , you need  to try them , all building depts except then up here , YMMV in Califorinacator  


Almost as good as a PC sawsall

[glenn kangiser]

You got that right.  I always have an impact wrench on the truck or around the house - Rotohammer too.

[PEG688]

Where up late tonight See ya around campus , PEG

[glenn kangiser]

I know -- At 9 pm I was outside running the jack hammer on the Bobcat when I realized what time it was and that the neighbors might want to sleep. :-?

[PEG688]

Used a few Titan's today , tool's required ,





Bolt's 1/2" x 6" ,




Pony walls under joist instead of post and beams ,




Seems slower to me , but it's what Lange com. does at least on the two kit house's we've done.

[glenn kangiser]

Thanks for the pix PEG.  I gotta get some of those now - and recommend them to the Steel company for stair installs.

[PEG688]

Can you believe the # of hold downs on that place , 22 or 24 IIRC Gravity must be goin on vacation , like the TV comericail said  

They'd be great for steel stairs , if you can get the rotohammer and impact in around the treads  :-/ :-/ That would be the only issue I'd see, but again it would [size=72]Depend   [/size]  on the details .

[glenn kangiser]

The ones I'm thinking of have a plate cut out for anchors then after anchored a cover goes over them.  Plenty of room.  The pans are then poured with concrete after I'm outa there.

You guys will need the hold downs to keep from floating away when global warming melts the polar ice caps.  Al warned you.

[PEG688]

I think most places would sink with all that cement board on them  

[JRR]

Youngins, like Glenn suggested ... a 2x4 is a great way to hold anchor bolts in location.  If you put the 2x4 "on edge", it supports itself for some fairly great distances ... of course, this means the holes for the bolts must be drilled thru the narrow part of the wood.  A drill press is nice for this, but I have made a simple tool out of 1/4" pipe fittings that allows for drilling pilot holes "on the square".  The 2x4 being "on edge" makes for less interference as the concrete is poured.

Another approach (that I prefer) is to use the same above rig to hold female nut inserts in place ... as opposed to bolts or re-bar.  This leaves the footing clear of re-bar or bolts which are destined to trip me up as I try to walk aroung the worksite.   You can make some great DIY inserts using all-thread rod to plant a nut and large-diameter flat washer deep in the concrete.  The washer has to be large enough to provide anchorage.  Of course, you can drill a plate or scrap bar to be used as washer ... the nut can be tacked to the washer for even more security.  Plastic or metal pipe is used above and below the nut & washer to keep concrete off of the threaded rod.  When the footing concrete is cured, the threaded rod is backed out using pipe wrench or doubled-nuts ... then the 2x4 is lifted, now you have a footing that is clear for foot traffic.  The nut & washer's are anchor points.  Temporary bolts can be dropped in the holes if needed to keep them clear.

Takes a little more up-front planning but works pretty well.