clay soils foundation design - to do not to do

[scherry]

ok, once again I am confronted with someone "just wanting a foundation design". I have a "soil sample" test result with LL 5, PL 19, thus P.I. of 26 and 82.8 passing the 200 seive. I know we have expansive soils here. I have read the code and based on IBC cannot determine whether I fall into their "must be checked" category. Given the general problems encountered herabouts with soils I am leery of using 1000 and saying ok. But the question really is, why do people do this? I have a floor plan - not a floor framing plan just a floor plan, with dims, and a nice little note that says all solid framing, beams columns and other structural elements shall be designed by a structural engineer. They do NOT want me to do that.I have two sheets of elevations showing a rock /brick veneer and concrete tile roof, but th (well, halleliuia, I just got saved but they will come back with another one in a few weeks so the question is still valid), i have a few columns called out and a 22 foot header which is labelled engineered header, but no posts or columns are shown (I know they have to be there, but...). I really would like to turn this down on the basis of there not being enough inbformation to design a foundation. I guess there are a number of engineers who do design foundations in this area with no more information than I have been rpovided with, but it just does not seem appropriate to me. IF it was a steel building and I could fairly accurately estimate the building loads and column placements I might be willing to do it, but not in this case where I do not even know which way the framing will go. Any comments? do many of you see this type of "foundation only" design based on an architectural sketch more or less? Can I determine whether or not I can use the table values based on the info i have or do i really need to ask for more data (yes, I think). I am looking at 1802.3.2 and table 1804.2. My (potential) client, by the way is a builder, and he got the design from a designer, no architect or other engineer involved. thanks for any input ya'll have.

 

[Focht3]

Hmmm,

Where is the site? (City, state only.) Were you provided with a geotechnical study for the subdivision? The developer should have one - you should look at it before you proceed.

My first inclination is recommend you pass on the assignment; but that is a business judgment that I cannot make for you. Can you develop this client, or is he shopping for fast & cheap? If he can be "trained", then you might take a stab at it. Otherwise, run fast!

Don't do the foundation without designing the header, columns, etc. Also design the the roof trusses, etc. Accepting a "partial design" assignment courts disaster. Treat it like a commercial structure in that regard, regardless of its' size or cost. I can assure you that the courts may well hold you accountable if you fail in your duty as a licensed engineer, even if the builder says, "I only want a slab design."



Please see FAQ731-376 for great suggestions on how to make the best use of Eng-Tips Fora.

 

[scherry]

thanks for the answer, you said what I suspected for the most part. I did not think to ask if the developer for the subdivision has a soils report, but I know the firm that did the test and can ask them , too. I am located in central Texas, Temple Killeen Waco with this type of project occiuring fron the north of Austin to the south of Waco. I am so tired of fighting off these kinds of half....projects and having to explain why they are dangerous. i think this particular builder would be willing to develop a relationship but only if it was fast and cheap, you know? Thanks for the help though. it is always nice to have another opinion on board.

 

[Focht3]

It gets no better south of Austin, either. San Antonio is full of them -



Please see FAQ731-376 for great suggestions on how to make the best use of Eng-Tips Fora.

 

[DRC1]

You and Focht3 know the engineering climate down there, but if you know engineers who have done this, talk to them. If they feel comfortable with this type of work because they know the capacity of the clay and know what loads to expect and some history with these designs(good I hope) then you might want to consider subing out the design to them. That way you maintain a relationship with your client, but you are not doing something that you don't feel comfortable with (not that I blame you). If they only do them because they need the work and with a little luck eveything will be okay, I would tell the client the design is too preliminary for a final design and get the information you need.
Good Luck!

 

[Laser28]

You are all right on with this issue. I would recommend talking to the developer and providing him with a proce for the entire project. Tell him that he is not doing himself a favour (yes - Canadian spelling) by parcelling out the design. He obviously needs a leader, someone who will shepherd the building thru the design and construction process, from geotech investigation to completion. There are obvious savings, such as only having to get up to speed once, and seeing the big picture.

Yes - by all means - see if this guy is trainable. Good luck, and remember, if you are hungry, a lawsuit and loss of your license are difficult to digest.

 

[gandersen]

Scherry:

I agree with all of the comments that have been given. Unless you need this type of work to pay the bills, my question to you is why work for this type of client? As I see it, he wants an engineering stamp as an insurance policy and to get through the permitting process, but he obviously sees no value added for your services. In the geotechnical field, some of us would call this a commodity client (one who doesn't see any difference in the value that you add to the process). The fact that you are conscientious sets you apart from your competition.

Some clients are sincerely looking to do the best job and others are trying to cut corners. My personal recommendation would be to position yourself in the market place so that these types of clients go to others. Your competition can have the headaches and defend themselves against the lawsuits and you can continue to practice sound engineering.

Good Luck