Replies

1. 
   zump00 | Apr 10, 2007 01:44am | #1

   have not but i would say to thru bolt also concrete fasteners since they are filled with concrete

1. 
   hartwig | Apr 10, 2007 04:32am | #3

   I had thought of using bolts into the concrete core, as well. My question is will the pressure of the ledger against the stucco and foam damage the surrounding stucco or is it resilient enough to distribute the force of the ledger as it gets fastened to the house? I don't yet have enough experience with this product and have not yet found any site
   describing this situation.

2. 
   Brian | Apr 10, 2007 04:02am | #2

   Are the ICFs up yet?

   If not - the Simpson product is great - I have used it with success.

   If they are already up, I would put the ledger directly to the concrete - cut the foam out with a chainsaw.  Through bolts would be best imho.

    

   Treat every person you meet like you will know them the rest of your life - you just might!
1. 
   hartwig | Apr 10, 2007 04:45am | #4

   At the moment I don't dare cut into the stucco, although it might be the final option. I'd hate to damage the surrounding finish.
   Thanks for the thoughts, Brian and Zump00.What do you guys think of ready rod, of large enough diameter to take the the shear weight of the deck, epoxied into the concrete core? The idea here is to support the ledger and deck without "squishing" the stucco and Styrofoam.

1. 
   Brian | Apr 10, 2007 02:01pm | #5

   With your stucco situation, I would consider posts and a girder on the house side as well, and skip the ledger.  Would that work in this application?

    Treat every person you meet like you will know them the rest of your life - you just might!

1. 
   hartwig | Apr 11, 2007 04:09am | #7

   Yes, the beam on posts is where we will go next(we've got a few weeks before we get into it). The HO expressed concern with that method because of the new perimeter drain, hence me inquiring about other methods (I did mention if we went that way we would hold the sono's out to clear the drain".
   I will also ask the HO's if they have any reservations re. cutting out the foam, as the PT ledger would be placed directly under a drip flashing which will define the height of he deck surface.

2. 
   hartwig | Apr 11, 2007 04:15am | #9

   I just re read one of your posts. You mentioned Simpson. Do they have a system for ICF's.

1. 
   Brian | Apr 11, 2007 01:30pm | #12

   Yes.  It goes in before you pour the concrete.

    Treat every person you meet like you will know them the rest of your life - you just might!

3. 
   user-144854 | Apr 10, 2007 05:23pm | #6

   In a situation where the stucco is already finished, I wouldn't be comfortable with anything short of girder/posts on the house side.  Any fastener into or through the concrete core will have at least a 3" cantilever, not counting any air space or thickness of the ledger.  NuDura makes a pretty neat stick-out joist hanger, but it's a pre-pour thing.

   }}}}

1. 
   hartwig | Apr 11, 2007 04:13am | #8

   Thanks for the heads up on the Nudura system. Just checked the site, that is sweet. Had the original builder been on it he could have used something like that. Yet we are in the "Great White North", takes a while for the good stuff to get here,...eh! Cheers.

1. 
   user-144854 | Apr 12, 2007 06:36pm | #13

   Checked with my ICF builder, and he confirmed my guess that the most efficient solution by far is to just do the post/girder routine on the house side.  He sent a drawing off once (fairly huge deck) for engineering analysis of a through-bolt retrofit, and it called for two rows of 1" bolts 12" o.c. staggered, with large backer-plates inside, cut back to concrete.

   Though it's irrelavent to this particular discussion, he also said that new construction entails cutting the foam (sloped down to avoid a straight shear joint) to let the concrete flow to the face of the finish surface, embedding L-shaped rebar tied to threaded rod and wall bar, then shimming for airspace.

   Any retrofit involving trimming foam and adding grout results in a cold joint with essentially no shear strength, and vertical forces will be resisted mainly by tension in the through-bolts (which changes with moisture content of the ledger), and friction of the ledger against stucco -- assuming that it's set without airspace, and just left to rot.

   Seems a lot easier to just dig some holes and add posts.

   }}}}

1. 
   hartwig | Apr 13, 2007 02:44am | #16

   The idea of a self supporting deck is appealing. We are considering a hybrid version ie registered to the house w/ a ledger while taking the weight off the ledger with the self supporting idea.

2. 
   IdahoDon | Apr 13, 2007 05:48am | #17

   ... two rows of 1" bolts 12" o.c. staggered, with large backer-plates inside, cut back to concrete.

   For heavens sake that's about as much overkill as I've ever seen on any residential house--ever.  If any engineer ever spec'ed that we'd have a significant issue.

    ...embedding L-shaped rebar tied to threaded rod and wall bar....

   Not according the engineers at ARXX, or the various engineers we've had over the years.   Again, that's a figment of his engineer's imagination.

   Any retrofit involving trimming foam and adding grout results in a cold joint with essentially no shear strength, and vertical forces will be resisted mainly by tension in the through-bolts (which changes with moisture content of the ledger),

   That's just silly.  Ledgers have been installed like that for decades with engineering approval to boot!  According to that line of thinking it would be impossible to even use a full length 2x to space a ledger.  What you're listening to is an engineer who is technically correct as to what is happening, but totally clueless as to the degree to which the reduction in sheer affects a load that would be reasonable.  The new situation doesn't fit the sheer force formula in his computer program so he is lost.

   Personally, I'd get a new ICF builder.

    

     

   Beer was created so carpenters wouldn't rule the world.

1. 
   user-144854 | Apr 19, 2007 05:33pm | #18

   "For heavens sake that's about as much overkill as I've ever seen on any residential house--ever.  If any engineer ever spec'ed that we'd have a significant issue."

   Well, that's why I said it's not done!  Remember, the issue here is not ultimate strength, but intolerance for deflection of bolts through the finished surface.  We're concerned with keeping rain out, not preventing the deck from falling down.  Same thing with the "cantilevered grout cold joint".  Sure, sufficient tension in the bolts can apply enough friction between the grout & concrete core to hold the thing up nicely, but it will move in response to normally seen forces (plus, it's brittle & rather friable), and this simply buggers the whole deal unless some way is found to weatherproof those penetrations in light of that movement.  Certainly it could be done short of those 1" bolts, but it does get complicated & costly, and relies quite a lot of attention to detail quality.  In cases where a girder/post arrangenent just won't work, trimming out the foam (and of course the plastic or steel ribs) to insert a full-length wood ledger in contact with the concrete core and adequately waterproofed can work.  Again, material & workmanship quality standards must be higher than encountered in more mundane house building scenarios.

   Thanks for the advice, but I think I'll stick with this ICF builder.  He has a stong reputation as about the best there is.

   }}}}

2. 
   IdahoDon | Apr 24, 2007 04:58am | #19

   Sure, sufficient tension in the bolts can apply enough friction between the grout & concrete core to hold the thing up nicely, but it will move in response to normally seen forces (plus, it's brittle & rather friable), and this simply buggers the whole deal unless some way is found to weatherproof those penetrations in light of that movement.

   Movement is present in all areas of a building's exterior, even within small elements that most people think of as static.  If a builder is relying on systems that require zero movement, they are in for many disapointments.

   There are examples of how not to flash deck ledgers in hundreds of thousands of houses, so your builder should be applauded for his concern.

   That said, it's a bit overly simplistic to suggest that a full length ledger can be reliably flashed, but a number of spacers, nothing more than very short ledgers, can not.

   We all need to work within our comfort zone, so it's within reason that what works for us, isn't the right thing for others, and visa versa. 

   If a deck produces loads large enough that the ledger detail demands such close attention then it should be designed into the icf blocks prior to the original pour if at all possible.  After the fact the retrofit connection would need an engineer's stamp.  We could find many engineers that would stamp our methods, and some that wouldn't.

   Best of luck with your deck. 

   Beer was created so carpenters wouldn't rule the world.

4. 
   IdahoDon | Apr 11, 2007 10:06am | #10

   The catch 22 is that to eliminate the possibility of damaging the synthetic stucco you're talking of pouring concrete on the foundation's backfill, which would rarely be considered fully settled if it's new construction.

   The stucco is easily cut and the ledger should be bolted to the foundation with threaded rod epoxied into the wall.  However, you don't have to inlet the entire ledger and it's perfectly ok to use PT spacers to hold the ledger off the stucco and provide a solid bridge between concrete and ledger.  You can also remove sections of foam and fill the space with concrete, mortor or even modified thinset to serve as the spacer and prevent compression of the stucco.

   Personally, I'd use two 3/4" galvanized threaded rods epoxied 4"-5" deep in the concrete core of the wall, every 48", with the rods 2" from the top and bottom of the ledger.  For the spacer I'd cut out a 3" wide by ledger depth slot from the foam around the threaded rod.  Fill the slot with high strength concrete protruding 1/2" from the stucco surface and mold a dome or slope to the top to better shed water.  A synthetic stucco patch can be used to help the concrete plugs resist water.

    

   Beer was created so carpenters wouldn't rule the world.

1. 
   hartwig | Apr 13, 2007 02:39am | #15

   I like the idea of furring blocks to get us out beyond the surface of the stucco so that it is a non issue re. compression and there is no need to cut out the entire ledger length of foam/stucco.
   We are debating whether to make the "blocks" out of square channel, of appropriate gauge from aluminum or even stainless. This way eliminating any chance of rot.

5. 
   ericicf | Apr 11, 2007 11:35am | #11

   We set bolts before the pour always. Inside or out doesn't matter.

   Our anchor bolt has a 2 1/2 x 2 1/2 x 1/8 inch piece of flat welded to it .

   This flat sits in the foam width acting as a bumper and a spacer for when you tighten up with your ledger.

   I'll take a pic of our bumper bolt and post it later in the thread.

   One of the P Engs who designed Nudura, came up with this several yrs ago.

   You will probably have to have local P Eng acceptance.

6. 
   JohnFinn | Apr 12, 2007 09:42pm | #14

   Simpson does have a ledger system for ICF's, but will only be of use to you if you have not filled the cells of your ICF's (they are place prior to pouring).

   I agree with others who are steering you towards an self supporting deck since your walls are up and done.

   Regards