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Uplift for Decks

jar546

jar546

CBO
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Oct 16, 2009
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Not where I really want to be
OK, so this is for commercial decks. Is this, or can this be applicable to residential decks?

1604.8.3Decks.​

Where supported by attachment to an exterior wall, decks shall be positively anchored to the primary structure and designed for both vertical and lateral loads as applicable. Such attachment shall not be accomplished by the use of toenails or nails subject to withdrawal. Where positive connection to the primary building structure cannot be verified during inspection, decks shall be self-supporting. Connections of decks with cantilevered framing members to exterior walls or other framing members shall be designed for both of the following:
  1. 1.The reactions resulting from the dead load and live load specified in Section 1606 and Table 1607.1, in accordance with Section 1605, acting on all portions of the deck.
  2. 2.The reactions resulting from the dead load and live load specified in Section 1606 and Table 1607.1, in accordance with Section 1605, acting on the cantilevered portion of the deck, and no live load on the remaining portion of the deck.
 
Oh, you mean this?

R507.8 Vertical and lateral supports.​

Where supported by attachment to an exterior wall, decks shall be positively anchored to the primary structure and designed for both vertical and lateral loads. Such attachment shall not be accomplished by the use of toenails or nails subject to withdrawal. For decks with cantilevered framing members, connection to exterior walls or other framing members shall be designed and constructed to resist uplift resulting from the full live load specified in Table R301.5 acting on the cantilevered portion of the deck. Where positive connection to the primary building structure cannot be verified during inspection, decks shall be self-supporting.
 
jar546 said:
OK, so this is for commercial decks. Is this, or can this be applicable to residential decks?

1604.8.3Decks.​

Where supported by attachment to an exterior wall, decks shall be positively anchored to the primary structure and designed for both vertical and lateral loads as applicable. Such attachment shall not be accomplished by the use of toenails or nails subject to withdrawal. Where positive connection to the primary building structure cannot be verified during inspection, decks shall be self-supporting. Connections of decks with cantilevered framing members to exterior walls or other framing members shall be designed for both of the following:
  1. 1.The reactions resulting from the dead load and live load specified in Section 1606 and Table 1607.1, in accordance with Section 1605, acting on all portions of the deck.
  2. 2.The reactions resulting from the dead load and live load specified in Section 1606 and Table 1607.1, in accordance with Section 1605, acting on the cantilevered portion of the deck, and no live load on the remaining portion of the deck.
Click to expand...

Don't see why not.

R501.2 Requirements. Floor construction shall be capable of
accommodating all loads in accordance with Section R301 and
of transmitting the resulting loads to the supporting structural
elements.
Click to expand...

That's in Section R501 - General. Since a deck is a floor and must be designed to accommodate all loads and transmit them to the structure, I'd say that includes uplift.
 

R301.1 Application​


Buildings and structures, and parts thereof, shall be constructed to safely support all loads, including dead loads, live loads, roof loads, flood loads, snow loads, wind loads and seismic loads as prescribed by this code. The construction of buildings and structures in accordance with the provisions of this code shall result in a system that provides a complete load path that meets the requirements for the transfer of loads from their point of origin through the load-resisting elements to the foundation. Buildings and structures constructed as prescribed by this code are deemed to comply with the requirements of this section.
 
jar546 said:
You might get some disagreement from deck experts here
Click to expand...

It doesn't take much searching to find someone, somewhere, who will disagree with just about anything in the codes. Are you arguing that decks DON'T need to be designed to resist wind (or seismic) uplift?
 
Physics does not differentiate between residential and commercial decks.

In the context of wood decks I have difficulty in identifying situations where vertical seismic loads would govern. Maybe this is why I have never seen such concerns raised before?
 
Mark K said:
Physics does not differentiate between residential and commercial decks.

In the context of wood decks I have difficulty in identifying situations where vertical seismic loads would govern. Maybe this is why I have never seen such concerns raised before?
Click to expand...

I occasionally drive by an older house that has a deck added onto the back. The house is facing a side street, so the rear is visible from the main road. The deck is easily 15, if not 20, feet above the ground, and the supports are 4x4 wood posts. The only "bracing" is a couple of 4x4 knee braces that can't be more than 24 inches long. If we were to experience an earthquake, there's no way that deck would survive.
 
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