IBC 2006 SPECIAL INSPECTION, PERIODIC. The part-time or intermittent observation of work requiring special inspection by an approved special inspector who is present in the area where the work has been or is being performed and at the completion of the work.

In theory the number of inspections needed to satisfy the "periodic" requirement is the number of inspections that the SI has determined are needed to convince him/herself that the intent of contract drawings/documents is being met.

In actual practice the frequency of periodic inspections is determined by the number of special inspector employed by a testing firm and the firm's current workload.  When the work load is heavy there are fewer "periodic" inspections because the SI is run from job to job.  When the workload is slow the SI is camped out on one job.

Like on masonry jobs, periodic means the SI doesn't have to see every single CMU block placed in a wall, but he still has to inspect the entire wall.  Similarly on periodic for reinforcing on concrete work, the SI doesn't have to see every single bar as it is placed, but he has to inspect all the bars once in place.

Also under reinforced concrete, "Inspection for maintenance of specified curing temperature and techniques."  Obviously the SI does have to sit there during the entire curing period, but he still has to perform the inspection.

Good question.

I am not familiar with Chapter 17 of the 2006 IBC. However, in the 03 and 06 versions, there is no provision that spells out a frequency for performing periodic special inspection.....to the best of my knowledge.

Check out these links

http://www.osbeels.org/docs/Periodic%20Special%20Inspection%20OSSC%20Interp%201702.pdf

http://www.bssconline.org/NEHRP2003/comments/C2.pdf  read commentary in Section 2.3

If asked I would say that the frequency of “periodic” is the frequency determined by the actual Special Inspector to satisfy him/herself that the work either does or does not conform to the intent of the contact drawings and specifications.  In all cases the design professional in responsible charge has the last word on the determination of the frequency of periodic inspection.  The Special Inspector and the SER should have a meeting of the minds on this matter before the work proceeds.

All to often the SI is left out of pre-con meetings and is denied access to the SER.  Contractors still have far too much influence over the process.

Thanks for the input.  Based on the first link by henri2, it looks like the UBC definition would push an inspector towards the view of boffintech.  If the scope is the same for periodic and continuous inspection, I guess it would have to be up to the inspector writing the final report.  

But the IBC language and the guidelines provided for the IBC provided by CASE seem to place the burden of specifying frequency of inspection on the "Registered Design Professional".  I still have not found any recommendations of what this frequency should be - even general guidelines.  How would you determine the specified frequency of periodic inspection?

Say you have a 10" thick slab with #5 EW on the bottom mat and the specified clearance is 1".  Do you specify how many slab bolsters to place?  No.  The number of slab bolsters  required to hold the rebar mat during its placement and through placement of plumbing, electrical, whatever, and then the concrete so that it remains at the required clearance is the number of slab bolsters required.

It takes what it takes.  No more and no less.


 

The EOR (or as it is currently RDP) defines it in his statement of special inspection.

JLNJ,

Is there any place for the EOR to find guidance on specifying this?

enginerding,
Here's what I do.  I sit down and think about what is important design-wise and how critical each construction feature is in regards to performance.  I also consider what areas contractors typically get wrong.  I establish hold points and inspect at those intervals.  As a minimum, I would probably visit the site near the beginning of a job and near the end.  I'd add visits inbetween based on hold points.  On a recent project for two tall steel stacks I visited the job site every fortnight.

Joe Tank

I went to the "Into to the Structural Provisions of the 2006 IBC" and asked the question where "periodic" was defined. The question was waved off with a "it's in the 'Definitions' at the beginning of Chapter 17." Of course there is a definition given, but it is not particularly meaningful.

In the body of Chapter 17 there are some specifics regarding certain types of construction (high strength bolts, for example, and for welds one is referenced to AWS D1.1).  

In my opinion, the entire inspection chapter is the result of bringing the UBC folks into the IBC fold. They (the UBC'ers) probably have a stronger opinion of what needs to be inspected, how often, and why. I don't posess such a strong feeling about the need or effectiveness of these "inspections".

In the end it seems to me that it is up to the EOR to specify and the Building Official to approve of the inspection program. If a liberal engineer meets up with a liberal building official the result may be not-very-frequent inspections. When everybody takes a conservative approach the cost of the special inspections may exceed the structural engineer's fee (I witnessed this happen on the design of a new High School). Sometimes it seems backwards to me that we will beat the geotech down to $15,000 for his professional recommendations, but then turn around and pay the testing arm of his firm $75,000 for field QA.