NZ - Imp 1 V Imp 2

[rowingengineer]

I am getting a fair bit of push back from engineers in NZ on imp 2 Vs imp 1 building. I think this is because when I define my building as IMP 2 the footings in seismic regions is greatly increased. I don't really like adjusting my IMP 2 vs IMP 1, based on the opinion on the footing designer. (I am a Australian engineer based in QLD so need to reply on teh local guys for seismic designs in the south island mainly)

I have reviewed the B1 and am fairly comfortable with my definitions for sheds and farm sheds.

Imp 2 - anything over 150m2 is imp2 for economic reasons - this would equate to roughly $60,000 for the structure excluding foundations.

Does anyone have some good definitions for farm/industrial sheds with low occupancy gernally below 3-4 people?

 

[dik]

Not familiar with the code. What is the distinction between imp1 and imp2. Can you set up a table with checkmarks to see what the overall features are?

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

 

[KevinNZ]

ASNZS 1170.0 supplement 12002 seems quite clear

Owners can of course ask for a higher level of design actions.

 

[dik]

I would suggest that if you can show or state that the structure is minor, isolated, rarely contains people and is not required as part of normal infrastructure that it qualifies as an imp1 structure. It should be easy to do.

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

 

[Retrograde]

If it is a farm shed I would take it as IL 1.

Not sure where the 150m2 rule comes from.

 

[rowingengineer]

NZ has a code which deals with importance level which should be governing over anything in the AS/NZS standards, if we ha to abide by the building code, some structures do not.

In this par of the code it does have a low economic cost requirement. the give examples of barns, sheds and ancillary buildings, however no size limitation. For me a 150sqm shed would be a large economic impact.

 

[KevinNZ]

Who made the wording in Clause A3? Should be 'and' not 'or'.

 

[dik]

I wouldn't think the low economic cost should enter into the criteria.

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

 

[Agent666]

Is the push back from people who have been ignoring the code for years?

I wonder what is their argument for not complying, not complying because it will be more expensive as you think isn't really a reason is it?

Oh, the hospital foundations were too expensive, so we just designed it for less load at IL3 instead of IL4. Is that ok, as that's essentially the same argument, right?

In 20 odd years of NZ design the only structure I've ever designed as IL1 was a fence. I think it is quite clear in the code the intent, it is as per the examples posted in your second post rowingengineer. Do you fit into one of these examples (ancillary building not for human habitation, minor storage facility (garden shed, farm storage, etc), backcountry hut).

IL1 just represents a lower risk. What does the clients insurer say about it, they are taking the risk if it is under designed.

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