Is there any reason when building a new addition that will have a deck. that a 2×10 PT deck ledger shouldn’t be included in the foundation forming and pour.
Eg. form a 10″ concrete wall. Add a PT 2×10 ledger to the insides of the outer form at the correct height. Pour the wall. Leave the 2×10 in place. When ready to build the deck, just add joist hangers and you are ready!
Seems like a good idea, but haven’t seen it done. Am I missing something??
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Replies
Usually the first floor framing sits on top of the foundation wall, often 2x10 framing. Generally a small step down to the deck, say 4" to 6", at least around here. 2x10 deck framing would only notch down into the concrete a few inches, and would get in the way of standard platform framing methods.
I do like the concept though. Have to think about how it could work effectively.
What are you missing?
How about mechanical attachment of the ledger to the concrete?
How about the deck being below the interior floor by the combined height of the mud sill, the first floor joists, subfloor and finish floor?
How about exterior insulation for the foundation?
How about flashing details?
Solar & Super-Insulated Healthy Homes
Riversong brings up some good points. We are working on a foundation now that has the floor joist attached in a manner you describe. The biggest obstacle that I see on the exterior would be the elevation difference between the exterior deck and the interior floor. You would be forced into having steps unless you plan to hang the floor joist. If these pictures end up attached, it shows the before and after. The ledger was tacked into the foundation panel. The galvanized bolts were drilled through the ledger and the foundation panel, threads held flush with the panel. This left enough that once the panels (1-1/8") were removed the bearing plates and nuts fit fine. Keep in mind that this is on the inside of the foundation so we have no flashing issues to deal with.
Edited 12/22/2008 4:34 pm ET by harryvermehren
Here's the before picture
That is very cool. I would think that you could upsize the ledger just a bit in order to have your deck step down from the door. LVL? I know that those stand up to weather better than regular lumber, but your not worried about moisture wicking into to it from the concrete? Just a thought, but again, very cool.
The let-in ledger doesn't look like it's treated. I woud consider that a structural beam, which is supposed to have a capillary break to the concrete underneath and 1/2" air space at all sides, particularly at the end grain. I suppose if you wrapped it with bituthane before the pour...
Riversong HouseWright
Design * * Build * * Renovate * * ConsultSolar & Super-Insulated Healthy Homes
The let in ledger in my pictures was pressure treated H/F. There is a small piece of 3/4" cant strip on the right side of the wall in the "before" picture. It was not treated, it is a sacrificial piece to form a bevel at the outer top edge of the foundation. Maybe that is what you are referring to.
Edited 12/23/2008 11:40 pm ET by harryvermehren
Out west they use orange incised pressure treated. You can just make out the incision marks in the photo. Quite different than the green junk we get here in the NE.
We do???
When I worked in Seattle in the mid-90's we did, I've seen it visiting friends in CO, and on several different threads here on BT over the years. Maybe it's not everywhere though. Where are you located? (Hint: fill out your profile ;-)
We did something similar when we built our deck.
But we didn't use the ledger board as the a form board. If you did that how would it drain? Wouldn't you be creating a pocket to collect water?
We used the form boards to hold the anchor bolts for the ledger in place during the pour. Then once you strip the forms you have your bolts ready to go and you can slip some spacers on to space the ledger off the concrete and the pre-drilled ledger board should just slip right on and bolt down.
Daniel Neumansky
Restoring our second Victorian home this time in Alamdea CA. Check out the blog http://www.chezneumansky.blogspot.com/
Oakland CA
Crazy Homeowner-Victorian Restorer
i've done that a couple times.
Yes, you are missing something. use a bunch of SS screws or some galvinized lags set into the ledger on the crete side before pouring. Without that mechanical tie to the crete wall, the ledger can pop right off, and the deck with it.
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This ledger board was used as the form as well. 6"x1/2" carriage bolts w/ nuts & washers inside and out; carriage heads IN, obviously, to bond into the 'crete.
Worked well in this app., not sure about on a house. Careful layout and consider everything!
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Our ledger was not the form, it was fastened to the inside of the form panel. The top 12" of the 8" thick concrete wall is actually only 6-1/2". By placing the bolts in the ledger and casting it in place, you eliminate the headache of the bolts not being a perfect 90 degree angle. It's tough enough drilling a 2x6 mudsill let alone a 2x12 with bolts staggered 16"oc. When we drilled the holes through the ledger and the form panel, we used a 5/8" hole for a 5/8" bolt and twisted them into the holes. The bolts had almost no slop so they did't move and they also kept the ledger from dropping. 16d duplex nails held the ledger tight to the form. Our ledger had to be level with the top of the foundation wall, but held down 3/4". we tacked a 1x2 to the top of the ledger to act as a grade line. The framer will remove the 1x2 when he installs the joists, and the plywood sub-floor will provide the shear connection from the joist to the ledger.Edited 12/22/2008 11:08 pm ET by harryvermehren
Edited 12/22/2008 11:13 pm ET by harryvermehren
Thanks again to all that replied. This forum is great.Agree with all the comments on some sort of bolt arrangement to hold the PT ledger onto the concrete, but it probably doesn't need to be as extensive as you would have if you were bolting it on to the rim joist with no concrete support shelf. (In one of my details(below) you can actually nail the sill plate to the top of the new PT rim which will keep it from twisting)In the northeast most decks are one step down at least so this isn't a big deal.Attached are a couple of possible details. Each has its pluses and minus. But what I like about both is the ease of flashing. No PT ledger board sticking out in to the weather directing all of the water into the KD framing. Just a simple flashing piece applied to the PT before the Joist hangers and you are done.Thanks again and great pictures.
This all makes great sense to me.
One detail I would add, however, is on the bottom of your cast-in-place ledger, I would tack a ripped triangle pulled out after curing to form a chamfer under the ledger board for drip edge.
I would worry that even tho it's PT, the pocket the ledger is sitting in could become saturated.
Good point. It might not be a bad idea to bevel the bottom of the ledger to create a sharp drip edge.
yeah thinking about it, you're not really bearing the ledger in the pocket formed by it--the connectionis made mechanically with j-bolts or whatever you're going to do-- so you could chamfer off the from the inside bottom edge of the ledger and never have any problem of water collecting there.
May I add:
Use drawing #1 and completely cover the ledger with tarpaper and roll flashing before installing hangers.
The PT needs to be fairly dry and kept dry during the pour. Staple 6 mil plastic on the inside of the ledger and wrap it over the outside of the lower form board to make a permanent capillary break.
The upper nails in the joist hangers will be nailed into the non-treated framing. Hmmm. I don't really like that.
If you are going to all this trouble, why not leave the ledger out and use blue screws directly into the concrete for the lower nails? Cheaper, faster, no ledger to install, flash, explain to the inspector, etc.
OB
A couple of other things: the ledger will be absolutely soakin wet by the time the pour is over. So it's going to shrink and is liable to be up off of the concrete ledge by the time all is said and done.
Bolting a deck ledger to the rim is a tried and true practice. If it ain't broke....
sounds like an equal amount of work (or more depending on the coop of the masons) compared to bolting a PT ledger to the crete after the fact. plus critical layout is necessary without changes, which NEVER happens in remod/building......
Dan Lynn, Dan Lynn Construction, Joliet, IL
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I think I was coming to a similar conclusion as to why you don't see this done this way very often.If you are not willing to trust your concrete sub to put the ledger in the right place then it makes no sense. And for big projects it makes sense to have clear lines of responsibilities for each sub. In my case, I do small projects and most times I am both the framer and concrete former. In this case I think doing it the way I have proposed will make my life a lot easier. Started this thread to see if I was missing something technical or is what more related to the normal work flow of the job site.Thanks again for all your ideas.