I’m in design stage for an elevated (10′) free-standing deck that will have masonry support columns. My question is: What is the best way to attach the horizontal deck structure to the columns?
The deck structure won’t be able to sit on top of the columns (as in a pier) since they will extend up above the deck surface and be the anchor points for metal railings. The columns will be 24″x24″, which will consist of 6″ thick stone veneer all the way around a 12″x12″ cmu/concrete core.
I have been considering using threaded rod installed horizontally in the column and protruding out the side to attach a mini-ledger board of sorts. Any suggestions or links to a good detail on this issue would be appreciated.
Thanks,
Rhys.
Replies
whoa. maybe you should talk to an engineer?
what kind of lateral loads are you designing for? earthquake? hurricane? where are you located?
is the veneer really going to be 6"?
if you somehow deal with the moment loads, you can certainly embed or epoxy in all-thread to handle the vertical/shear loads. i'd want the ledger bearing directly on the structural core, with careful flashing details all around it to deal with the veneer.
I'd never be allowed to build anything like that without an engineer's stamp, though.
k
Located in southwest missouri, so no earthquake or hurricane, only isolated tornado events.
Yes the veneer is 6", it's 6" shotstone limestone with brushed mortar. That's what is on the rest of the house. Kind of rustic look.
I was planning on talking to an engineer, but I just want to get some ideas of different techniques that others have used. I was considering that I might end up having to bear the loads on the concrete core. Any help with a flashing detail would be appreciated.
Thanks.
"southwest missouri, so no earthquake"
Really? Ever hear of the New Madrid fault? Puts the San Andreas to shame. I mean, there's big shows on the subject on the Discovery Channel.
But those masonry columns are built up around a 4x6 treated timber - placed on top of a footing and attached at both ends. The masonry comes after it's in place.
Edited 2/9/2009 5:12 am by peteshlagor
New Madrid is a bigger concern for southest mo. I am in Springfield area. While damage from New Madrid quakes in the 1800's had damage that extended a couple of hundred miles up the Ohio river valley, damage areas were very limited to the west. I am about 200 miles west of New Madrid. We are in Zone 1.
One idea I was considering was making the columns out of solid concrete with rebar, using 12x12 block as a form. This is just an idea, would need to run it by engineer.
OK, since we're all clear that you should talk to an engineer, I'll set that aside for a bit, since my kitchen remodel is on hold and I'm bored.
I see two questions here:
1) What column design is going to work for the structure as a whole,
2) How to attach the deck to said columns.
I personally wouldn't put much thought into #2 until I'd answered #1.
A 12" sq. column, whether filled block w/ rebar in the cells or solid concrete with rebar should be strong enough in terms of vertical load bearing capacity. But you need to work out the footings for those.
First, you need something with enough area or "skin friction" to not sink/drive into the ground (depending on soil condition). Second, you need a way to keep those columns from tipping over. As they get taller, the overturning forces get stronger, e.q. country or not.
You get a bunch of folks up there all swaying in time to the music and they could rock that sucker over if you haven't addressed the rotational forces adequately.
Can you give more details about the deck/house overall? I'll go back and re-read your post, but I don't recall specific sq. ft. Will the deck abut the building?
k
Edited 2/9/2009 12:15 pm ET by KFC
As far as footings for columns and tipping over, I figured something like a pad at least as large (24x24") as the column and sinking the footings/column 4 feet intothe ground. Frankly, this for sure is one thing I would be looking for the eng. to design/recommmend. I have a small tractor with backhoe, so digging is no big deal.
Deck would abut the house. Reason I thought I should build as free-standing is that the builder did not use a rim joist at the back wall of the house. The 12" tall I-joists are actually parallel to the back wall, and instead of using a rim joist, there is just another I-joist at the back wall. It has always concerned me about the compression loads of the wall that sits on top of it. That's why I don't want to bolt through it.
Deck area is about 16'x20' with 20' parallel to house. There is also to be a second area that is about 6'x25', with 25' parallel to house.
Thanks for your help. I want to have some education before talking to the engineer, just to make sure he knows what he's doing and so I don't sound like a moron.
Thanks for your help. I want to have some education before talking to the engineer, just to make sure he knows what he's doing and so I don't sound like a moron.
Yeah, that's how I was approaching it. It can't hurt to brainstorm abut the possibilities prior to talking to the P.E., as long as you don't irritate them with too many preconceived notions, or insult their pedigree.
The i-Joist "rim board" isn't too uncommon, but you're right, you can't bolt into it. And even if you could, deck ledger to house connections are notorious for rotting out house framing eventually. Free standing decks are great for avoiding that, but you lose the ability to laterally restrain them by tying back to the house. so you end up with x-bracing, diagonals, etc.
If you've got a back hoe, maybe a reinforced grade beam tying the columns together, kind of an upside down moment frame, would be a good bet. What's the space under the deck?
k
k
The space where the deck will go is all accessible now for any type of required excavation. But the plan includes putting pavers down and having a patio area under the deck. I was going to look at some sort of waterproofing system to stop rainwater and make the area dry.
rhys