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Hurricane Clips

J

Jrrichards1775

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Jul 20, 2015
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As You know I'm fairly new to the building codes,

The retired building inspector always required hurricane clips on all structures in our Jurisdiction. Now I have a contractor that is telling me that its not required per code. He has installed blocking at the truss to help with the up wind as required by code. These are stick built Truss members and not pre-engineered with a gusit plate. So I can't find anything stating specifically about wind clips of such. Just a Fastener Schedule for structural Members Table R602.3 in the IRC.

Also does any one have any checklist references that you may use or have used in the past to do your inspections by in all disciplines.


Any Help would be appreciated.
 
Engineered trusses require the H ties, Cut in framing goes with blocking and nailing schedule. Code Check is handy and can get it for Res. & Com. codes.
 
"Uplift connections" are always required, trusses just give you the values you need to hit which makes it simple. I think toenails are good for 80-100 lbs each. And a 2.5A is good for around 600....
 
Significant Changes to the 2012 IRC excerpt; “Where rafter or truss spacing does not exceed 24 inches on center, the prescriptive connection requirements (toenailing) of Table R602.3(1) are permitted to be used under either of the following conditions:

Where the uplift force does not exceed 200 pounds, or
Where the roof pitch is 5:12 or greater and all of the following criteria are met:

90-mph wind speed

Wind Exposure Category B

Maximum building width of 32 feet

Maximum roof overhang of 24 inches

In the first condition, the 200-pound maximum capacity for conventional rafter-to-wall or truss-to-wall connections using toe-nails is based on capacities calculated from AF&PA’s National Design Specification (NDS) for Wood Construction. The applicable uplift force for a particular installation may be determined from Table R802.11

When either of the conditions above is satisfied, an engineered connector may be used but is not required.
 
The IBC now uses ultimate wind speed design I do not know if the IRC changed in the 2015 edition.

Did your state define if it is 3 second gust, sustained or ultimate wind speed for the 100 mph minimum?
Do you use Table R301.2.1.5.1 BASIC WIND MODIFICATION FOR TOPOGRAPHIC WIND EFFECT
 
Unlike the 2012 IRC the 2015 IRC reflects the IBC for design purposes.

2012 R802.11; "Where the basic wind speed does not exceed 90 mph"

2015 R802.11.1; "Where the basic wind speed does not exceed 115 mph"

BASIC WIND SPEED. Three-second gust speed at 33 feet above the ground in Exposure C (see Section R301.2.1) as given in Figure R301.2(4)A.
 
Year edition of each of the adopted codes is important here, as you can see there was a shift in the underlying methodology for wind design from 2012 to 2015 in the I-Codes. Up to 2012 the I-Codes used 3 second gust and fastest mile for wind speeds. Starting in 2015 there was a shift to ultimate design wind speed and nominal design wind speed. The wind speed numbers went up quite a bit, but the thresholds for requiring design also went up to reflect the change in methodology. In some cases, Long Island in NYS for example, prescriptive framing can be used in a larger area than under the previous code editions.
Another detail; it is not so much north-south location in South Carolina, but rather east-west location. The farther east the higher the wind speeds...
 
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To my knowledge, "hurricane clips", ties or any other specific product have never been required prescriptively. Some form of uplift resistance has always been required. But putting in an H clip is an easy way to cover that base in most circumstances. Your truss shop drawing will tell you how many pounds up uplift the connection needs to resist. I have had several instances where an inspector blindly "required" an H clip. It has become a norm in the business, even though it is not always legitimate.
 
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Sifu said:
To my knowledge, "hurricane clips", ties or any other specific product have never been required prescriptively. Some form of uplift resistance has always been required. But putting in an H clip is an easy way to cover that base in most circumstances. Your truss shop drawing will tell you how many pounds up uplift the connection needs to resist. I have had several instances where an inspector blindly "required" an H clip. It has become a norm in the business, even though it is not always legitimate.
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No they are not, But, provide an easy way to address the uplift.
 
mark,
I agree with your statement that the H-clips address the uplift. Even on plan review and field inspections they make verification easier. You can see the clips from a distance and most of the time you can determine that they used the proper amount of fasteners. The problem you have in the field with nails is determining that three hand driven nails are in the truss tied to the T-plate from the floor and that the correct size and length was used.
 
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