2007 IRC Supplement requires 2 hold-down tension devices per deck now.

[Nick Gromicko]

http://www.nachi.org/gallery/exterio...-device-3d.jpg

and for more info: www.nachi.org/deck-inspections.htm

[Marcel R. Cyr]

Nick,it is my understanding that this would apply for Jurisdictions that have adopted the 2006 IRC.
For those that like to follow up on the Codes that Nick is presenting, it can be found here in PDF format.

http://www.iccsafe.org/cs/codes/2007...ent/IRC07S.pdf Page 35-36

Hope this helps

Thanks Nick.

[Nick Gromicko]

I see some unanswered questions with this change: What about when the joists run parallel to the ledger?... is the bracket installed using blocking? When the joists run perpendicular to the ledger do the deck joists and house joists have to be lined up and have to match O.C. spacing? What about truss joists?... you can't attach a new load to them, even if you could figure a way to do it. When installing a deck to a home with a finished basement the contractor now has to open the ceiling, no? The contractor now has to lift carpeting to install more nails in the home's subfloor? Wow.

[Joe Farsetta]

This is why some jurisdictions adopt portions of the code and reject other portions.

[Richard A. Hetzel]

Why would there be joists running parallel to the ledger?

[Nick Gromicko]

One reason is when you have a tiered deck with but 1 step between tiers. For architectural effect they often like to switch the decking from tier to tier.

Checkerboard decking also has 1/2 the joists running parallel to the ledger.

And the other reason they do this is for safety so that it is easy for the eye to see the steps. This quote from "Building a Deck" by Scott Schuttner: "A change of direction in the decking can visually alert users to steps or other impediments."

[Tim Spargo]

As far as the joists running parallel to the ledger, I'd have to see it on some plans. My experience here would have been where joist direction was not perpendicular to ledger, the load path (post/beam) would be designed to accommodate this. Blocking couldn't be used to bear weight where the joist direction changes.

In theory, as most of our decks / balconies are engineered here, I can imagine the plans would call out to simply install additional blocking to accomodate the mention of checkerboarding the decking material. ie blocking every 16/24" oc in the joist bay depending on manu. specs for their decking materials. Many of the trex and similar products would be fine with 16" oc. Other concerns could be raised by this application as well, such as the blocking bearing the weight of live/traffic load and decking.

Interesting find though. I've used simpson straps up and over plating and to studs from decks and covers, that design looks alot like the Strong Wall and Hardi Wall seismic/shear wall panels.

Tim

[mnahrgang]

Forgive me if this sounds like a stupid question, but what is the purpose of these tensioners in the first place? I've yet to see one installed, and from the images they don't appear to do anything that lag bolts and proper hangers wouldn't already do. What am I missing?

[Nick Gromicko]

Unlike lag bolts, the hold-down devices attach to the home's floor joists (which is why subflooring nailing is required), not just the home's band joist.

And unlike lag bolts, the hold-down devices attach to the deck's joists, not just the ledger board.

It's a joist-to-joist connector.

[Nick Gromicko]

I can see these things being of some benefit when there is an outer cantilever. The joist hangers at the ledger board are upside-down on a deck with an outer cantilever because the joists are lifting up instead of applying a load down.

[Patrick Carter]

Originally Posted by mcyr

Nick,it is my understanding that this would apply for Jurisdictions that have adopted the 2006 IRC.
For those that like to follow up on the Codes that Nick is presenting, it can be found here in PDF format.

http://www.iccsafe.org/cs/codes/2007...ent/IRC07S.pdf Page 35-36

Hope this helps

Thanks Nick.

Marcel, thanks for posting the IRC 2007 PDf

[John Evans]

Reading sections 502.2.2.1.1, 502.2.2.2.2 & 502.2.2.2.3 indicates the tension hold downs are only required when you cannot attach a ledger board by standard methods using specified lags or bolts.

[Nick Gromicko]

Thanks John. Can you post what you see that indicates that to you please?