• Welcome to the new and improved Building Code Forum. We appreciate you being here and hope that you are getting the information that you need concerning all codes of the building trades. This is a free forum to the public due to the generosity of the Sawhorses, Corporate Supporters and Supporters who have upgraded their accounts. If you would like to have improved access to the forum please upgrade to Sawhorse by first logging in then clicking here: Upgrades

Retaining wall question

Sifu

Sifu

SAWHORSE
Joined
Sep 3, 2011
Messages
2,799
http://i1269.photobucket.com/albums/jj584/raspicher/HPIM0157.jpg

The picture is of a "natural" retaining wall. (the wall is 12' at the highest point) It was built during the construction of the house which is under permit but it is not connected to the house, nor does it support any part of the house. It is under the driveway and parking pad. We don't require permits for accessory structures. The code (2006 IRC only) specifies engineering required but if we don't require accessory structure permits and there is no structure surcharge can I reasonably walk away from it? If it is an accessory structure I don't think I would have jurisdiction, on the other hand if it subsides I want protection from the attorney. I need pretty strong code language to justify everything I do, especially if I am going to delay a job again and cause more expense.

For those of you who remember the scenario, this is the same location I had questions on concerning the very tall foundation walls. BTW, still don't have the design for them. They are on their 3rd DP now and they tell me its coming.
 
This wall exceeds the scope of the IRC and thus would be covered by the IBC if you have adopted the IBC. A 12 foot tall retaining wall is a non trivial thing even with no surcharge. Not sure that I would call this a retaining wall. More likely it is just a steep slope that could easily fail.

One of the roles of codes is to protect people from their own stupidity. This is more evidence that those who are most confident that they know what they are doing are often the most dilusional.
 
Answers:

Francis, I don't know what you mean by surcharge from the wall as an ascending slope.

Ice, there are acouple of those dayight drains. One is definately from a catchbasin in the surface of the pad, the other may be from a proposed downspout that is not actually in use.

Mark, We have not adopted the IBC and as I said we do not permit or inspect accessory structures. Since it is not part of the house I am not sure I even have the authority to act on it.

I asked myself this: if this wall and driveway were 100 feet away from the house, would I have the authority to act on it? If the failure of the wall does not impact the house is it within the scope of the code or even part of the permit? (keeping in mind wouldn't permit an accessory structure wall) If not how is it different in its current location? Typically the MOE ends at what? In this case the pad/driveway is adjacent to the front step, is that where the MOE would end in a residence? Do I have the authority under the IRC to regulate the driveway, sidewalk, yard?

I have no illusions that this might be a problem in the future. I am wondering where the line is drawn in protecting every person from every stupid thing they may do.
 
Look at 2012 IBC Section 1808.7.2 and 1804.2. I believe that these requirements have been around for a long time.

Many accessory structures could fall within the scope of the IBC
 
I'm little handcuffed here at home, I only have 03 IBC and 09 IBC with me. 06 and 12 IBC are in my office. But if the sections to which you are refering are concerning foundations near descending slopes I am not sure that would apply. The adjacent foundation is a 10" poured wall that has (supposedly.....I am still waiting on the final as built design) been designed and approved by an engineer. That foundation begins below the level of the bottom of the retaining wall. I do realize many accessory structures fall within the scope of the IBC, and even the IRC but we have not adopted the IBC, and we don't inspect or enforce any codes on anything that is not a one or two family dwelling. If a house permit comes in with a detached garage I am instructed to inspect the house but NOT the garage. Thats why I am questioning the validity of "inspecting" this wall.

I think I'll lay it in the lap of my BO anyway. We have no written policy about accessory structures (or anything else), just his orders. So I'll show him the photo and get his ruling. If he wants engineering it will be his call. If he wants to walk away, his call again.
 
Sifu,

Was the slope cut to accommodate the house?

Or is the house wall retaining fill?

By the look of the picture, the retaining wall must be worth as much as a new Winnebago.....and that's what could be parked on the driveway.

Whatever the outcome, the drain needs to be extended away from the rock wall.

If it's any consolation, most slope failures are a slow motion event.
 
Last edited by a moderator:
Jurisdictions that have not adopted a general system of building codes and enforcement policies should give thought to the consequences of lack of such regulations.

On one hand if an individual will be the only occupant you could adopt the approach that he is responsible for his own stupidity. Why should we deny somebody the opportunity to obtain a Darwin Award?

This is less justified if other individuals will use the building and will unwillingly be subjected to the consequences of poor design and construction. What about the neighbor when there is a fire in the building or when a landslide dumps a bunch of dirt on his property or in a stream thus causing other problems. What about the safety of emergency responders who drive fire trucks on unstable local roads.

Code enforcement tends to mitigate bad practices of some contractors and thus helps to protect the individuals contracting with ignorant or unethical contractors.

There is also the concern that without some enforcement of construction you will end up with a number of poorly constructed buildings that will deteriorate quickly and that will impact the desirableness of the community.

This comes down to the reality that my right to do whatever I want ends where the rights of others begin. What was acceptable when each house was located on a 40 acre homestead is less acceptable when people are in closer proximity.
 
Sifu:

The question might be, would a retaining wall failure undermine the house foundation, or do harm to another’s property? It sure will take out that parking slab, or garage slab if that’s what it’s intended to be. I don’t think you will find anything in any code which says you shouldn’t have engineering and geotech involvement on a 12' high retaining wall with a parking lot surcharge on top of it. For a dry laid stone wall that doesn’t have much batter, and that drain pipe and any water behind the wall will likely undermine it and wash it out over time. The fact that that wall is standing at the moment doesn’t mean much when the earth and loads behind it start acting and moving. You give no info. about how that wall is actually built, the soil conditions, fill and drainage behind the wall, etc. These guys have been jerking you around for months, not providing design info. they promised months ago; going through several supposedly different engineers, probably because none of them can justify what’s been done, so they back out. I don’t understand why this job isn’t shut down until they start complying and providing what they promised. It sounds like a fairly complex structure which probably exceeds the IRC in many ways other than the ones you have questioned. And, it shows a builder who is in way over his head given the crap you have shown. If your boss isn’t giving you any support or direction, let him handle it.

I agree with MarkK. You work in a strange jurisdiction where you permit and inspect one and two family homes to the IRC, but anything more complicated than a prescriptive house design/build can fly under the radar, because nobody has any jurisdiction and you don’t have to comply with the IBC, when the IRC clearly doesn’t address the design situation. Doesn’t your State or County have a building code which must be followed for all construction? I’m quite sure that everything in the IRC complies with the IBC, but there are many many more things that are covered by the IBC which are not covered in the IRC. After all, the IRC is really just a conservative simplification of the IBC, which when followed and not exceeded, should allow for basic house construction without the involvement of Professional Architects and Engineers. However, there are many things that I can do complying with the IBC and using my engineering judgement and experience, which are not covered by the IRC. You ought to suggest that your boss or the BO take over on this one, and quite wasting your time and limited experience.
 
dhengr said:
Sifu: You ought to suggest that your boss or the BO take over on this one, and quite wasting your time and limited experience.
Click to expand...
Sifu,

If it's any consolation, gaining experience is a slow motion event.
 
I didn't give any info about how the wall is built because I don't know. I showed up and there it was. I have no real doubts about whether the code would want engineering review. My doubts are about whether it is an accessory structure. If I had a policy or adopted codes and a reasonable system behind me I would not be in this situation to begin with. Forget about whether it may work or not, I am trying to figure out if it is an accessory, if it is I may not have the authourity to anything with it. I have dealt with a tall wall on a property before, but we had the tools in place to deal with it and it wasn't even a question. Here, my tools are limited. As far as how it could effect people, I have thought about a 100 scenarios where someone ends up at the bottom and I end up in court. I am giving this to the BO, so I am trying to gather as much intel as possible. I admit I don't have the experience to answer some of these questions but I do have the intelligence to ask them. The problem is nobody behind me has that experience either.
 
Sifu:

That does seem to be one hell of a job to be doing some of your learning on. Not much support from your superiors, maybe because they don’t know what they are doing, a kinda screwed up set of criteria about what you should or shouldn’t have some authority over. And then to top it off it seems you have a builder who is in way over his head, doing lots of crazy things which don’t indicate much real building knowledge, experience or planning, working on a difficult lot and building without enough professional design help. You will be the smarter for this experience, but it is kinda like you are being thrown to the wolves with such a difficult builder, who presents so many crazy situations and problems, and then nobody above you with a depth of experience or knowledge, to back you up or give you guidance. Keep asking questions here and maybe see if you can finding a more experienced BO in a nearby community who knows what he’s doing and will help mentor you, and answer questions with some local knowledge. That can be a rewarding relationship, and maybe lead to some future opportunities.

I don’t know the (your) exact definition of an accessory structure, I think in terms of dangerous structures, whatever they may be, which need some engineering attention and judgement, not just a builder’s wild imagination. Many things do not fit within the prescriptive codes like the IRC. That does not mean they can or should be ignored. A 8'x12' tool shed out in the back yard is an accessory structure, in my mind, and a 12' high retaining wall could hurt someone if it failed and should not be done on a whim and a fancy. I would think this fits in the same category as the tall foundation walls on this building project. It should be reviewed and signed off on, by an Registered Engineer, even if it doesn’t have a roof on it.
 
Sifu, Basically if the house can exist as is without the retaining wall I would consider it an accessory structure. Even though you do not permit accessory structures that doesn't mean they get to build whatever they want, it still has to meet code. I would speak to the builder recommend the involvement of an engineer and explain why. Then I would go back to the office and write a memo to file about what I recommended and why I had no authority to enforce it. that way when they don't have the involvement of an engineer and the system fails you will not be liable.
 
ICE said:
If it's any consolation, most slope failures are a slow motion event.
Click to expand...
The wall looks alot like the one that failed on me while backpacking in a slide area on the old Big Oak Flats road in Yosemite near El Captain-- and that was not a slow motion event it seemed like every rock I tried to grab hold of came loose as I was crabbing sideways watching a few tandem loads of dirt, old pavement, and rocks tumble down the hill including about 15 feet of the wall and old road.

It was starting to get dark and I wanted to make the top before pitching camp so I may not of studied it as well as I could have before crossing. After the slide I camped about 100 yards further up the road.
 
2006 IRC

ACCESSORY STRUCTURE. A structure not greater than 3,000 square feet (279 m2) in floor area, and not over two stories in height, the use of which is customarily accessory to and incidental to that of the dwelling(s) and which is located on the same lot.

R105.2 Work exempt from permit. Permits shall not be required for the following. Exemption from permit requirements of this code shall not be deemed to grant authorization for any work to be done in any manner in violation of the provisions of this code or any other laws or ordinances of this jurisdiction. (emphasis added)

Building:

...

...

3. Retaining walls that are not over 4 feet (1219 mm) in height measured from the bottom of the footing to the top of the wall, unless supporting a surcharge.

...

R403.1.7 Footings on or adjacent to slopes. The placement of buildings and structures on or adjacent to slopes steeper than 1 unit vertical in 3 units horizontal (33.3-percent slope) shall conform to Sections R403.1.7.1 through

R403.1.7.4.

R404.1.8 Rubble stone masonry. Rubble stone masonry foundation walls shall have a minimum thickness of 16 inches (406 mm), shall not support an unbalanced backfill exceeding 8 feet (2438 mm) in height, shall not support a soil pressure greater than 30 pounds per square foot per foot (4.71 kPa/m), and shall not be constructed in Seismic

Design Categories D0, D1, D2 or townhouses in Seismic Design Category C, as established in Figure R301.2(2).

R404.5 Retaining walls. Retaining walls that are not laterally supported at the top and that retain in excess of 24 inches (610 mm) of unbalanced fill shall be designed to ensure stability against overturning, sliding, excessive foundation pressure and water uplift. Retaining walls shall be designed for a safety factor of 1.5 against lateral sliding and overturning.
 
I am familiar with what is exempt from a permit by code, and familiar with the fact that not having an inspection is not permission to do whatever you want. All good things that must be put into practice by the responsible parties. It has been determined to be outside of my jurisdiction, pretty much like I figured. I presented the facts, definitions and possibilities as I saw them. Brought up life safety, safety of the structure, safety of the adjoining property and liability. The only thing they want inspected are residential dwellings. I wrote a hefty disclaimer (by order of the BO) and will repeat it when they pass the final. If the wall doesn't retain dirt or people at least I will have done what I could. (All very well documented)
 
it seems to me that the contractors and/or customer have emploied some anty gravity materilals, since gravity the enemy of all things standing up. Since they do not seem to think these structures will fail grqaavity must have been removed ftom the equation.
 
While a failure of the wall is probably a slow motion event, I pointed out that falling of a person is not. Didn't matter. In a similar situation before in a different place the wall was fine. Lots of engineering and good construction. It was the H/O that didn't want an rail obstructed lake view across the back of his yard. He had made a real nice level yard for his kids to play in, then drop off of! He saw the reasoning in the requirment and an appropriate barrier was installed.
 
"shirley the insurance companies would be covering some of it"
Click to expand...
"Shirley, the insurance companies would be covering some of it"
 
Last edited by a moderator:
You must log in or register to reply here.
Top