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I apologize in advance for a rather lengthy post, some of which is presented in a bit of a narrative fashion, but I would love some other opinions on this issue I'm currently dealing with that's causing a lot of heartburn.
Context
Conflict
Upon submittal, the third-party plans examiner commented that our drainage does not comply with CBC R801.3, which for the uninitiated states the following:
In areas where expansive soils or collapsible soils are known to exist, all dwellings shall have a controlled method of water disposal from roofs that will collect and discharge roof drainage to the ground surface not less than 5 feet (1524 mm) from foundation walls or to an approved drainage system.
Response
As an architect who works almost exclusively in an area of California with highly expansive soils with astute and knowledgeable plans examiners, my first thought was, "Why have I never been called on this?"
I first pointed out to the Building Official and the third-party plans examiner (PE) that all three previous phases were approved with downspouts discharging to splash blocks, and that R801.3 clearly says "not less than 5ft from foundation walls." Emphasis mine. In my opinion, this code section is clearly talking about a condition where the foundation is composed of a stem wall that supports the structure above, and separates soil on one side from habitable (or non-habitable) space on the other side. The CBO and PE replied, "Well that's not how we interpret it." I fail to see what is up for interpretation, as their interpretation would require them to fully omit a critical word in that code section.
Undeterred and believing all they needed was the proper documentation to hang their hat on, I pressed on. I was able to track down an ICC interpretation of that specific code section, IRC Interpretation 14-3, which addresses this exact question. Here it is, unadulterated, in its entirety:
R801.3 Roof drainage. In areas where expansive or collapsible soils are known to exist, all dwellings shall have a controlled method
of water disposal from roofs that will collect and discharge all roof drainage to the ground surface at least 5 feet (1524 mm) from
foundation walls or to an approved drainage system.
Q: When a building utilizing a slab-on-grade, post-tensioned foundation, is constructed on expansive soils, is water
collected at the roof and discharged to the ground surface required to be discharged no closer than 5-feet from the edge
of the slab-on-grade foundation?
A: No. Water collected at the roof and discharged to the ground surface is required to be discharged at least 5 ft from
foundation walls only, this provision does not apply to slab-on-grade foundations. Saturation of expansive soils by
excessive water can lead to failure of the foundation because additional loads are imposed on the foundation wall by
expansion of wet soil. Discharging roof water away from foundation walls serves to minimize saturation of expansive soils
adjacent to the foundation walls.
When I presented this to the CBO and PE, they again rejected it and essentially said, "That's just an interpretation, and we don't agree with their interpretation."
So, I reached out to the geotech, who suffice to say is an authority in his field, and the Geotechnical Engineer of Record (GEOR) on this project and thousands of others throughout California. He assured me within one minute over the phone that this was a non-issue he could clear up no problem. He reviewed the on-site geotechnical investigations, and wrote a letter, along with a modified geotechnical report, stating that discharging to a concrete splashblock would not have any adverse affect on the specific soil conditions documented on site. He also stated that in his professional opinion, discharging to a splashblock to dissipate the energy of the discharge, and directing that drainage to an overland swale into adjacent landscape planters, would constitute an approved drainage system (it's important to interject here that the University's Building Official (CBO) had previously stated in an email that we would need to have the GEOR sign off on an alternative design).
When we presented the GEOR's letter and updated geotechnical report to the CBO, he stated, and I'm roughly quoting here but it's not too far off: "Your geotechnical engineer has lost credibility with me." He rejected the GEOR's stance, even though he previously just invited it. He then said that his primary concern was that the added hydrostatic pressure from the water in the soil causing expansion and contraction could have a negative impact on the foundation.
I reached out to the structural engineer, again a highly qualified individual with decades of experience on all project types. He essentially said that it's actually much simpler than all that: R801.3 doesn't apply at all, because it's referring to a non-engineered (prescriptive) foundation. He designed and engineered the mat slab, post-tensioned slab on grade foundation to specifically resist the pressure caused by the expansion of the exact, tested soil on that specific project site. R801.3 is there as a catch-all to protect the foundation's integrity when it has not been specifically engineered by a licensed engineer per the explicit recommendations of a geotech report. (I think the way R801.3 is phrased is very telling: "In areas where expansive or collapsible soils are known to exist." In my opinion, that seems to imply that you have not tested the soil, but are installing conventional/prescriptive foundations in soil that has not been tested, but you're aware that expansive/collapsible soils are known to exist locally.)
You can probably guess where this is going... also a no-go.
So, I come to you all to tell me whether I'm crazy or not. Am I wrong? Are all my engineers wrong? What recourse do we have when a third-party consultant and the CBO rely on 'interpretations' that, in my opinion, go beyond the definition of interpretation? Very curious to hear what this community's thoughts are on this matter.
Thanks for reading!
Context
- We (architect and consultant team) are submitting permit/construction drawings to a University for a faculty housing development, in California.
- Three phases of this development have been completed over the last decade or so; we are submitting for the final phase.
- The University is using a third-party code consultant to review plans and recommend approval.
- The land in question had a geotechnical investigation performed by an licensed and experienced geotechnical engineer; the report indicated the presence of expansive soils, consistent with the adjacent three phases.
- The foundation system is a mat/raft slab on grade, post-tensioned, and again designed by a licensed and experienced structural engineer.
- The roof drainage system, as originally designed, consisted of standard downspouts terminating at concrete splash blocks, consistent with the previous three phases approved by the University, and again designed by a licensed and experienced civil engineer.
- Also important to mention that the site was designed with rolled curbs, and all the site improvements for all phases (gutter, sidewalk and most of the streets) were completed together during the earlier phases, and are an existing condition on site.
Conflict
Upon submittal, the third-party plans examiner commented that our drainage does not comply with CBC R801.3, which for the uninitiated states the following:
In areas where expansive soils or collapsible soils are known to exist, all dwellings shall have a controlled method of water disposal from roofs that will collect and discharge roof drainage to the ground surface not less than 5 feet (1524 mm) from foundation walls or to an approved drainage system.
Response
As an architect who works almost exclusively in an area of California with highly expansive soils with astute and knowledgeable plans examiners, my first thought was, "Why have I never been called on this?"
I first pointed out to the Building Official and the third-party plans examiner (PE) that all three previous phases were approved with downspouts discharging to splash blocks, and that R801.3 clearly says "not less than 5ft from foundation walls." Emphasis mine. In my opinion, this code section is clearly talking about a condition where the foundation is composed of a stem wall that supports the structure above, and separates soil on one side from habitable (or non-habitable) space on the other side. The CBO and PE replied, "Well that's not how we interpret it." I fail to see what is up for interpretation, as their interpretation would require them to fully omit a critical word in that code section.
Undeterred and believing all they needed was the proper documentation to hang their hat on, I pressed on. I was able to track down an ICC interpretation of that specific code section, IRC Interpretation 14-3, which addresses this exact question. Here it is, unadulterated, in its entirety:
R801.3 Roof drainage. In areas where expansive or collapsible soils are known to exist, all dwellings shall have a controlled method
of water disposal from roofs that will collect and discharge all roof drainage to the ground surface at least 5 feet (1524 mm) from
foundation walls or to an approved drainage system.
Q: When a building utilizing a slab-on-grade, post-tensioned foundation, is constructed on expansive soils, is water
collected at the roof and discharged to the ground surface required to be discharged no closer than 5-feet from the edge
of the slab-on-grade foundation?
A: No. Water collected at the roof and discharged to the ground surface is required to be discharged at least 5 ft from
foundation walls only, this provision does not apply to slab-on-grade foundations. Saturation of expansive soils by
excessive water can lead to failure of the foundation because additional loads are imposed on the foundation wall by
expansion of wet soil. Discharging roof water away from foundation walls serves to minimize saturation of expansive soils
adjacent to the foundation walls.
When I presented this to the CBO and PE, they again rejected it and essentially said, "That's just an interpretation, and we don't agree with their interpretation."
So, I reached out to the geotech, who suffice to say is an authority in his field, and the Geotechnical Engineer of Record (GEOR) on this project and thousands of others throughout California. He assured me within one minute over the phone that this was a non-issue he could clear up no problem. He reviewed the on-site geotechnical investigations, and wrote a letter, along with a modified geotechnical report, stating that discharging to a concrete splashblock would not have any adverse affect on the specific soil conditions documented on site. He also stated that in his professional opinion, discharging to a splashblock to dissipate the energy of the discharge, and directing that drainage to an overland swale into adjacent landscape planters, would constitute an approved drainage system (it's important to interject here that the University's Building Official (CBO) had previously stated in an email that we would need to have the GEOR sign off on an alternative design).
When we presented the GEOR's letter and updated geotechnical report to the CBO, he stated, and I'm roughly quoting here but it's not too far off: "Your geotechnical engineer has lost credibility with me." He rejected the GEOR's stance, even though he previously just invited it. He then said that his primary concern was that the added hydrostatic pressure from the water in the soil causing expansion and contraction could have a negative impact on the foundation.
I reached out to the structural engineer, again a highly qualified individual with decades of experience on all project types. He essentially said that it's actually much simpler than all that: R801.3 doesn't apply at all, because it's referring to a non-engineered (prescriptive) foundation. He designed and engineered the mat slab, post-tensioned slab on grade foundation to specifically resist the pressure caused by the expansion of the exact, tested soil on that specific project site. R801.3 is there as a catch-all to protect the foundation's integrity when it has not been specifically engineered by a licensed engineer per the explicit recommendations of a geotech report. (I think the way R801.3 is phrased is very telling: "In areas where expansive or collapsible soils are known to exist." In my opinion, that seems to imply that you have not tested the soil, but are installing conventional/prescriptive foundations in soil that has not been tested, but you're aware that expansive/collapsible soils are known to exist locally.)
You can probably guess where this is going... also a no-go.
So, I come to you all to tell me whether I'm crazy or not. Am I wrong? Are all my engineers wrong? What recourse do we have when a third-party consultant and the CBO rely on 'interpretations' that, in my opinion, go beyond the definition of interpretation? Very curious to hear what this community's thoughts are on this matter.
Thanks for reading!