How to Install a Ledger Board to Concrete
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Attaching a ledger board to concrete block
- This topic has 37 replies, 1 voice, and was last updated 5 years, 3 months ago by
jponto07.
Viewing 20 posts - 1 through 20 (of 38 total)
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August 9, 2016 at 8:46 pm #554022
As part of a siding repair job, I uncovered some serious issues with the adjoining deck. Every other joist sits ON the outermost portion of the block, but the rest of the joists were simply attached to the face of the wood siding with joist hangers and 1 5/8″ screws.
My plan is to install a ledger between each of the joist that penetrate the block to allow me to support the now floating joists. To make matters worse, the span between joists is a full 24″.
I'm looking for suggestions/confirmation that I'm on the right track here as I've never attached a ledger to CMU. I feel like this solution is best, but the specific attachment method is still debatable.
Would you use sleeve anchors or go with an adhesive anchoring method?
August 9, 2016 at 8:54 pm #554027
In that type of situation I have made sure to place my bolts in the solid portion of the block webs. I like using a 1/2″ LDT. If the block is fragile you may have to use mesh and anchoring adhesive to attach it.
Andrew
A Working Pro since 1995!
Member since March 26, 2014.
August 9, 2016 at 9:06 pm #554031
In that type of situation I have made sure to place my bolts in the solid portion of the block webs. I like using a 1/2″ LDT. If the block is fragile you may have to use mesh and anchoring adhesive to attach it.
It seems stable, but I haven't drilled into it as of yet. @overanalyze, are you saying Not to use the wedge anchors or that you prefer the LDT type more?
August 9, 2016 at 9:12 pm #554034
I prefer the LDT's over most other masonry anchors. Drill it and bolt it. I find expansion anchors can be finicky.
Andrew
A Working Pro since 1995!
Member since March 26, 2014.
August 9, 2016 at 9:27 pm #554042
Block really does not have enough meat to fasten to unless you hit a core fill location. The webs of a block are only about 1 1/2″ thick and using a 1/2″ anchor only leaves about 1/2″ on either side of the anchor. way to little for an anchor to develop full strength. You can use a Read head Dyna Bolt which is made for hollow units or an epoxy anchoring system. I would go with one of them. look at the Readhead of Hilti catalog for some ideas. Regular wedge anchors do not hold well in block.
August 9, 2016 at 9:42 pm #554049
Anonymous
Inactive
Is the block grouted?
What code do you guys use for decks there? Here we use DCA 6.
Even if your AHJ hasn't adopted DCA 6, it is, in my opinion, an excellent guide.
According to DCA 6, deck ledgers should only be attached to filled cores, and they should be epoxy anchored.
I personally would not do it any other way.
Also, why are you filling in with short pieces of ledger board, instead of redoing the whole thing?
Delta
August 9, 2016 at 10:21 pm #554058
Also, why are you filling in with short pieces of ledger board, instead of redoing the whole thing?
There is actually no existing ledger. Given that every other joist penetrates the block wall, a continuous ledger isn't possible. I guess I'm treating this like a cantilevered set up…the ledger is interrupted every 48″ or so.
What code do you guys use for decks there? Here we use DCA 6.
As far as I know, it's still the 2012 version of the IBC.
August 9, 2016 at 10:29 pm #554059
ChadM Moderator
Rogers, Ohio
I agree with 7 Delta – only attach to filled cores. Would it be simpler to just come out a ways, set a couple posts, and throw a beam under all the FJ's? Probably be quicker than screwing around attaching a bunch of mini ledgers.
Chad
A Working Pro since 1993
Member since 12/07/2013
August 9, 2016 at 10:43 pm #554062
Inactive
I agree with 7 Delta – only attach to filled cores. Would it be simpler to just come out a ways, set a couple posts, and throw a beam under all the FJ's? Probably be quicker than screwing around attaching a bunch of mini ledgers.
Lateral bracing would also, in most cases, be required, when building a free-standing deck.
But still, that might be the best and easiest option.
There is actually no existing ledger. Given that every other joist penetrates the block wall, a continuous ledger isn't possible. I guess I'm treating this like a cantilevered set up…the ledger is interrupted every 48″ or so.
The joists are not resting on top of a sill plate, on the block wall? 😮
How do you mean they penetrate? Deck must be below the floor level of the house, eh?
Delta
August 9, 2016 at 11:48 pm #554070
Why not install a full ledger underneath the joists?
I will also echo what others have said and find the solid cores unless the whole thing was grouted solid. I don't like wedge anchors. They make 1/2 concrete screws that work better. But if you're hitting a solid cell, I vote epoxy. Along with construction adhesive.
August 10, 2016 at 1:07 am #554079
I'm looking for suggestions/confirmation that I'm on the right track here as I've never attached a ledger to CMU. I feel like this solution is best, but the specific attachment method is still debatable.
Is the CMU filled with concrete or empty? I would cut out the face of a cell every 2 or 3 feet shove a wire down there and see if it is empty. If empty I'd shove some paper down there and fill with mud with a length of thread all or a threaded anchor coming out. Good luck with that.
August 10, 2016 at 5:51 am #554118
I am not a expert but I think Chad has the right idea of putting some posts and a beam under the joists.
August 10, 2016 at 6:20 am #554120
More detail:
The blocks are not filled. As for the way that the joist penetrate the outer layer of the block…it looks like someone took the back side of a hammer to the block and made a hole big enough to shove part of the joist into (the 9 1/4″ height does not penetrate…it's been notched down to 5″ or so).
It looks like the joists hit the house at the intersection of the block foundation and the sill plate, half above below…hence the notching.
There are currently 2 beams running under the joists, at approximately 1/3 and 2/3 distance from the wall. Those are both fine, but the connection to the wall still needs some attention.
Attachments:
August 10, 2016 at 6:25 am #554128
You can kind of see on the picture what the two joist types are doing. The further is notched into the block, while the nearer was attached to the siding.
August 10, 2016 at 6:32 am #554132
RonW Moderator
Holladay, Tn
I am not a expert but I think Chad has the right idea of putting some posts and a beam under the joists.
Have to agree. I think Chad's post and beam suggestion would be the way I would go.
Ron
A Working Pro since 1994!
Member since March 26, 2014.
August 10, 2016 at 7:24 am #554160
I think I would cut them all back as necessary and install a full length single or double ledger board as necessart fasten it per the IRC 2012 deck ledger requirements (IRC Scetion 507) with lags or ledger locks as possible into the wood. Where you will be fastening to the block, I think I would fill the cores then attach to that or at a minimum use the epoxy and screen anchors they make for hollow block.
Also make sure to get a holdback installed like the DDD1 or DTT2 by Simpson.
Deck failures can be to dangerous not to set them up to the new codes and the connection to the house is one of the most important connections and the most prone to failure
Decks are to dangerous not to set them up to work per code.August 10, 2016 at 7:46 am #554168
I'll look into the post and beam option that Chad mentioned, but I'm not very confident that I can actually dig a hole under the deck to begin with.
I'll take some pictures of the under side when I make it back to the site.
August 10, 2016 at 10:34 am #554194
Inactive
I think I would fill the cores then attach to that or at a minimum use the epoxy and screen anchors they make for hollow block.
I wouldn't use those to hold a deck ledger, personally.
I'll look into the post and beam option that Chad mentioned, but I'm not very confident that I can actually dig a hole under the deck to begin with.
You could probably pull some deck boards, and then auger a couple footing holes.
Delta
August 10, 2016 at 12:24 pm #554244
(the 9 1/4″ height does not penetrate…it's been notched down to 5″ or so).
I'd cut them all back the same and fill the blocks and set threaded anchors in them.
August 10, 2016 at 12:58 pm #554246
I think I would fill the cores then attach to that or at a minimum use the epoxy and screen anchors they make for hollow block.
I wouldn't use those to hold a deck ledger, personally.
I'll look into the post and beam option that Chad mentioned, but I'm not very confident that I can actually dig a hole under the deck to begin with.
You could probably pull some deck boards, and then auger a couple footing holes.
Delta
the epoxy and screen anchors are are rated at in excess of 2500 lbs pullout in hollow block. as long as the block is soun, that is more than a lag is rated at in wood.
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How to Install a Ledger Board to Concrete
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