How to anchor sill plate over hollow core foundation blocks?

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  #1  
Old 01-17-18, 01:02 PM
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How to anchor sill plate over hollow core foundation blocks?

I'm replacing a section of sill plate (around 8'), The blocks in that section are hollow. The current, rotted, plate was not anchored.
  • Should I even bother attempting to anchor it/bolt it down?
  • If I need to anchor it, how much of the block do I fill with concrete and how do I keep the wet concrete from dripping through to the bottom of the wall?
  • What kind of anchor can I use? The wall above will restrict the height of any tool I use. I can access the sill plate from the basement. I was thinking of putting a fabric "dam" at the bottom of the block and filling the core with concrete. While the concrete is still wet, I'll put the new sill in place and drop long bolts through pre-drilled holes that are aligned with the center of the core.

Thanks in advance for any advice.
 
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Old 01-17-18, 01:10 PM
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If you don't want to fill the entire core of the block use whatever to stop the concrete at whatever depth you need. I often use soda bottles crammed into the void. I don't know how well inserting anchor bolts into wet concrete at the same time you install the seal will work. I've always set the anchors first that way you can be assured they are solidly planted. When the isn't room for an anchor bolt I'll use a metal tie down strap and nail it to the edge of the joist or sill plate.
 
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Old 01-17-18, 02:43 PM
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Thanks @marksr.
I'd like to set the anchor bolts first, but then I wouldn't be able to wedge the replacement sill into place.
So, would you set the metal tie-down into the wet cement?
 
  #4  
Old 01-17-18, 03:37 PM
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If it wasn't anchored before I don't know why you would worry about trying to anchor it now.

Only way an anchor is going to do any good is if the cement blocks are slugged solid. Anchoring to a single cement block on the top row when it isnt slugged and tied to the others below it with rebar is pretty pointless, imo.
 
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Old 01-17-18, 07:36 PM
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That's a good point @XSleeper
One reason I was thinking about anchoring is that the area seems to have been patched by a previous owner. Beyond the area I'm working, I did find at least one bolt. So, I thought that maybe a previous owner had cut corners.
 
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