attach block to footer

Started by MarkAndDebbie, July 20, 2007, 08:02:58 PM

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MarkAndDebbie

July 20, 2007, 08:02:58 PM
I've been busy doing manual labor (unusual for me) - I don't think I think as well tired. But now I'm looking back over the week thinking I made a mistake...

I am doing the 1 1/2 story with a 4' block wall (bendspace). I have a guy to lay the block next week. We poured the footer today. Nothing is sticking out of the footer right now. I am planning on putting rebar and pouring a void solid every 4' and pouring a bond beam on top with rebar. I'm thinking I should have had some/all of that rebar sticking up out of that footer.

What can I / should I do? Is the mortar sufficient to the blocks on the footer?

glenn-k

#1
July 20, 2007, 10:08:25 PM Last Edit: July 20, 2007, 11:40:08 PM by glenn-k
I would suggest drilling with about a   7/8 rotohammer drill  and sticking 5/8 rebars about 3 feet long into the footer maybe 8 inches to 12 inches embedment.  Blocks should be 16 inches so start about 4 inches from one end and drill on 16 inch centers.  5/8 rebar needs about 13" laps so that should work.  

Blow out the holes - then grout the bars in with non-shrink grout -cheaper than epoxy.  Pourstone or Rockite are a couple brands -

If permits and inspections are involved you may have to ask an engineer and get signed instructions we commonly call an RFI - request for information.

Added info--- I re-read and see yoiu are not pouring all solid, so in that case you may want to only do the one you are pouring solid.  I would go as deep as possible on the embed less a couple inches above the soil, unless you need the engineer - then follow his directions.

n74tg

#2
July 21, 2007, 05:19:20 AM Last Edit: July 21, 2007, 05:24:38 AM by n74tg
I did a drystack wall on my house, but used 3/8" rebar on 23" centers and that worked out real well.  So, if you're wanting 1/2" or 5/8", try 46" centers.  Again, this is for a drystack wall (no mortar between blocks), so the spacing will be different than for a mortared wall.

My verticals stuck up as much as 3 feet out of the footer.  It wasn't difficult to thread the blocks over the verticals as the wall was built.  

There are pics all about it in the blog address below.  Please read the post on "rebar safety" in the archive dated 2006-07-09.

Good luck.

P.S.  Are you going to buy bond beam block, or "make them."  Likewise, are you going to want your vertical rebar pieces to terminate inside the bond beam?  If so, a commercially made bond beam block probably won't work.

Let us know what you end up doing.

MarkAndDebbie

#3
July 21, 2007, 06:06:10 AM
How long should I wait till I drill it? I Poured Friday at noon.

Glen, just to clarify - My footer is only 8" thick so I need to embed 6" not go all the way through and into the dirt?

BTW - I just had my first inspection (footer before pour). He was pleasant (and out of the truck for less than 60 seconds). My guess is that he knew the guy helping me with the footer and knew he was competent. He didn't even walk to see the far trench. The next inspection is foundation - call it pre-framing. I don't think I'll have  trouble with the inspection.

I was going to buy the u-block - I'll have to check/think about the rebar coming through it. I think some of the have knockouts.

Rover

#4
July 21, 2007, 06:30:03 AM
I thought I would reply in the event you are sitting around this Saturday morning wondering what to do. (sorry Glen).

The sooner you drill; the 'softer' the concrete.  I'd start ASAP.

You are correct, don't drill out of the bottom of the footing because the rebar will rust with direct contact to the dirt.

Re the U blocks.  They would make a nice bond beam.  Is it possible to just drill holes if there aren't knockouts.

glenn-k

#5
July 21, 2007, 09:13:59 AM
Not even a problem Rover.  I know you know what you are doing on this.  :)


JRR

#6
July 21, 2007, 02:32:27 PM Last Edit: July 21, 2007, 02:49:13 PM by JRR
Another approach wouid be to just depend on the block foundation for resistance to "up lift".  

What's a footing?  Just a massive band of, sometimes reinforced, concrete.  Attached to the ground??  ... well not really, except possibly for backfill, ... mostly it just weighs a great deal and would be hard to move.

The manufacturers of masonry surface bonding cement makes some astounding claims.  If you were to put a coat on the inside and outside of your blocks, keeping them from separating  ...and filled a great number of the cavities with low grade mortar or concrete  ... used sill plate anchor bolts that nearly reached the footing .... You'd have a pretty massive rack-resistant structure that would secure your building pretty well.  And you would never have "mechanically" attached foundation wall to the footing.

To increase the mass you might consider making the walls a couple of blocks highter.  

Or, you could add metal tie-down straps directly from many of  the joist ends down to anchor bolts in the footing.

But would the code guy continue to be happy?  Probably!  But best to ask.

glenn-k

#7
July 21, 2007, 02:49:14 PM Last Edit: July 21, 2007, 02:50:20 PM by glenn-k
Good point, JRR.  I also have looked at footings as just a bit more weight that is attached to the bottom.  Sometimes it is a pretty serious attachment - sometimes not.

I am familiar with how the foundation and reinforcing steel in it becomes an integral part of a rigid frame design in a steel building.  

It seems that most of the steel in a house foundation or block walls will never come into play unless a large earthquake happens or...

:-/

I love the workmanship on that wall. :)

JRR

#8
July 21, 2007, 02:51:12 PM
Now that's one way to add steel to a foundation wall!

MarkAndDebbie

#9
July 24, 2007, 08:38:19 PM
rented a hammer drill. used the rocktite stuff (whatever the quickcrete brand name is). Turned out great. Caution - that stuff sets up FAST.

glenn kangiser

#10
July 24, 2007, 11:55:29 PM Last Edit: July 24, 2007, 11:56:14 PM by glenn-k
Sounds great - I forgot to mention that we only mix a small amount at a time - we use a grout bag with the end cut off a little larger to fill the holes fast.
"Always work from the general to the specific." J. Raabe

Glenn's Underground Cabin  http://countryplans.com/smf/index.php?topic=151.0

Please put your area in your sig line so we can assist with location specific answers.

MarkAndDebbie

#11
July 25, 2007, 07:43:26 PM
QuoteI thought I would reply in the event you are sitting around this Saturday morning wondering what to do. (sorry Glen).

The sooner you drill; the 'softer' the concrete.  I'd start ASAP.

You are correct, don't drill out of the bottom of the footing because the rebar will rust with direct contact to the dirt.

Re the U blocks.  They would make a nice bond beam.  Is it possible to just drill holes if there aren't knockouts.

Thanks for the "start sooner" advice - the concrete was still soft. The guys are going to notch the U blocks. They have a saw and a diamond blade. They will make two cuts from the edge at the bottom of the U and the knock out the tab left between.
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