R408.6 Clarification

[skp1190]

Hello, just wanted some clarification as to the wording of R408.6 Finished Grade.

"The finished grade of under-floor surface shall be permitted to be located at the bottom of the footings; however, where there is evidence that the groundwater table can rise to within 6 inches (152 mm) of the finished floor at the building perimeter or where there is evidence that the surface water does not readily drain from the building site, the grade in the under-floor space shall be as high as the outside finished grade, unless an approved drainage system is provided."

How does one determine "evidence" of how high the groundwater table can rise, or that the surface water does not readily drain from the building site? Would it be something seen in the original soil report of the site (attached)?

I live in a swampy area with a high water table, our home had a 6ft crawl space dug, and have had issues with significant amounts standing water in our crawl space. Our builder did not install a foundation drain system, even though it was recommended in the soil report (Utah code amendment allows this recommendation to be ignored unless it is explicitly required in the soil report). Furthermore we signed an amendment to our agreement that cleared them of any liability related to the soils in our area. I'm wondering if our builder violated any codes that may have resulted in the wet crawl space.

 

[Yankee Chronicler]

How does one determine "evidence" of how high the groundwater table can rise, or that the surface water does not readily drain from the building site? Would it be something seen in the original soil report of the site (attached)?

One hires a geotechnical consultant to install monitoring points and to periodically check the monitors are record the ground water level. Ideally, this should extend over at least a full year. If that's not feasible, then the monitoring should be done for two or three months during the wettest part of the year.

 

[Mark K]

One hires a geotechnical consultant to install monitoring points and to periodically check the monitors are record the ground water level. Ideally, this should extend over at least a full year. If that's not feasible, then the monitoring should be done for two or three months during the wettest part of the year.

Talk with the geotechnical engineer. Then install a drainage system.

 

[Paul Sweet]

Or a sump pump.

 

[skp1190]

Talk with the geotechnical engineer. Then install a drainage system.

I had a geotechnical engineer come out to do a report on the water issue. Paid a few hundred bills. Pretty much just said "install drainage system + sump pump".

I understand that is the recommended fix, my question is more pertaining to the builder and if they are liable in any way for not installing a pump or taking any other measures to prevent water in the first place (we built the home with them a couple years ago).

 

[skp1190]

One hires a geotechnical consultant to install monitoring points and to periodically check the monitors are record the ground water level. Ideally, this should extend over at least a full year. If that's not feasible, then the monitoring should be done for two or three months during the wettest part of the year.

Is this not something that should have/was done on the site w/ the original soils report before starting development (see attachment)?

 

[ICE]

Is this not something that should have/was done on the site w/ the original soils report before starting development (see attachment)?

From the soils report:

 

[skp1190]

From the soils report:View attachment 12927

Only issue I see is that Utah code has an exception to R405:

"Exception: When a geotechnical report has been provided for the property, a drainage system is not required unless the drainage system is required as a condition of the geotechnical report."

I feel like the wording from the soils report could be argued that it is *recommending* drains but not saying they are *required* because they use "would be required" and "would be a wise precaution".

 

[Mark K]

I had a geotechnical engineer come out to do a report on the water issue. Paid a few hundred bills. Pretty much just said "install drainage system + sump pump".

I understand that is the recommended fix, my question is more pertaining to the builder and if they are liable in any way for not installing a pump or taking any other measures to prevent water in the first place (we built the home with them a couple years ago).

Unless the contractor had a design obligation the contractor is only responsible for building according to what was required by the construction documents.

Who decided not to follow the geotechnical engineer's recommendations? Did the Owner play any role in deciding not to install the drainage system?

The least expensive solution is to install the drainage system.

 

[Mark K]

Only issue I see is that Utah code has an exception to R405:

"Exception: When a geotechnical report has been provided for the property, a drainage system is not required unless the drainage system is required as a condition of the geotechnical report."

I feel like the wording from the soils report could be argued that it is *recommending* drains but not saying they are *required* because they use "would be required" and "would be a wise precaution".

This is an argument that the building department cannot require you to install the drainage system. The problem is that the water in the soil doesn't care what the building code says.

 

[steveray]

This is an argument that the building department cannot require you to install the drainage system.

Because they can't....

 

[mtlogcabin]

R405.1 Concrete or masonry foundations.
Drains shall be provided around concrete or masonry foundations that retain earth and enclose habitable or usable spaces located below grade.
Is the crawlspace usable or habitable? If not then R405.1 is not applicable.

R408.6 Finished grade.
The finished grade of under-floor surface shall be permitted to be located at the bottom of the footings; however, where there is evidence that the groundwater table can rise to within 6 inches (152 mm) of the finished floor at the building perimeter or where there is evidence that the surface water does not readily drain from the building site, the grade in the under-floor space shall be as high as the outside finished grade, unless an approved drainage system is provided.

The evidence is in your report that soils do not drain well and a drainage system is required. The contractor should have followed R408.6 and either filled in the crawlspace or installed an approved drainage system.

Why did you dig a 6 foot crawlspace?

 

[Paul Sweet]

Almost all geotechnical reports are written with recommendations rather than absolute requirements because of professional liability concerns. At one timw geotechnical consultants were getting sued left and right.

Unfortunately there's much you can get from the contractor since you "signed an amendment to our agreement that cleared them of any liability related to the soils in our area."

It is possible to install a drain system inside the crawl space, so you don't have to excavate the outside perimeter of the house to install a drain.

 

[classicT]

Almost all geotechnical reports are written with recommendations rather than absolute requirements because of professional liability concerns. At one timw geotechnical consultants were getting sued left and right.

Having started my career in the geotechnical and SI world and progressed onto being a BO, I am in agreement. Geotech reports are structured as recommendations because they are often pre-design investigations. Unfortunately, I will acknowledge that many projects I've seen have had the geo investigation as an afterthought once the structural and architectural designs are already complete.

Once a structural engineer uses the recommended design values provided in the report (bearing capacity, seismic, etc.), that report should no longer be considered as recommendations. They are the basis of design from which the structural engineer has completed their design.

As a code official, where the design team for the structure/building have not followed all of the geotech's recommendations, I have required that the geotechnical engineer of record (GER) collaborate with the structural engineer to provide approval for the limited/partial use of the design values. The structural engineer should not be picking and choosing recommendations from the geo report - take the whole report, get a new one, or get mutual agreement between the engineers.

 

[steveray]

Furthermore we signed an amendment to our agreement that cleared them of any liability related to the soils in our area.

Sooooo....you signed an agreement kind of admitting you knew the soils were bad and now you want to hold someone responsible?

Although I might argue it's a water issue, not a soil issue.....

 

[ICE]

Unfortunately there's much you can get from the contractor since you "signed an amendment to our agreement that cleared them of any liability related to the soils in our area."

It is possible to install a drain system inside the crawl space, so you don't have to excavate the outside perimeter of the house to install a drain.

An agreement related to soils might be about suitability for bearing capacity as opposed to drainage. In either case an agreement to waive code requirements is most likely unenforceable and perhaps illegal on the part of the contractor/developer.

A perimeter drain for a foundation that is six feet deep will not work. A sump pump along with adequate site surface drainage and roof gutters would make the difference however, the root of the problem is building in what has historically been a swamp. The soils report was for the entire development and I wonder if other houses have been built with the same result?

According to the soils report, the ground water level was found to be 1.5' deep in several tests. It was noted that this test took place during an extended dry cycle and the level could rise. Why there has been no mitigation measures implemented is a question for the building department.

 

[steveray]

An agreement related to soils might be about suitability for bearing capacity as opposed to drainage. In either case an agreement to waive code requirements is most likely unenforceable and perhaps illegal on the part of the contractor/developer.

A perimeter drain for a foundation that is six feet deep will not work. A sump pump along with adequate site surface drainage and roof gutters would make the difference however, the root of the problem is building in what has historically been a swamp. The soils report was for the entire development and I wonder if other houses have been built with the same result?

According to the soils report, the ground water level was found to be 1.5' deep in several tests. It was noted that this test took place during an extended dry cycle and the level could rise. Why there has been no mitigation measures implemented is a question for the building department.

Drain the swamp!

 

[steveray]

 

[ICE]

These screen shots come from the soils report:


There is the smoking gun. The soils engineer states that the site is suitable... only if the recommendations in the report are followed.


Foundation drains are "recommended". In other words, don't build without them. The statement pretty much rules out basements ... so a six foot deep crawlspace should have been rejected without some extraordinary measure to repel water.

I think it is clear that the building department bumped their head on this one. Of course, the may just be my negative nature.

 

[steveray]

Yeah...don't know how that plays with the Utah law, but the "suitable if recommendations are followed" does tie it up a bit...