Existing Porch Column Footing Adequacy 1

[Builder604]

I have been asked to verify an existing 6x6 wood column footing adequacy. The backstory is that the client has been asked to provide building permits for a porch and roof addition constructed around 10 year ago. The client had a general contractor install a roof over a rear porch supported with 6x6 wood columns; however, county has no record of then building permit so he has to apply for the permit now to get it on record. The building inspector requested an engineering letter to certify the column footings are adequate. The porch is a brick perimeter foundation with brick rowlock. The concrete is poured inside the brick rowlock. The columns are set inside the brick rowlock in the slab. The footings are obviously not visible without destructive investigation and after ten years there is no movement or settling noted. I am considering writing the letter basically stating the footings are not visible but based on the current conditions, no settling/movement, etc. that the footing appears to be adequate along with some other disclaimer verbiage.
I haven't don't alot of experience on existing foundations/footings and was wondering what your opinions are with this situation? Thanks in advance.

 

[racookpe1978]

What state, what city?

What frost zone to avoid movement? Seismic or hurricane rules for that county?

 

[Builder604]

The project is located in Nash county, nc. Seismic n/a, wind speed 100 mph and frost line 12".

 

[JAE]

I think all you can do is write a letter stating your observations as to what is visible.

Then state a conclusion that from these observations that no movement has occurred over several years, that the footing "appears" to b adequate.

But then I would point out the following:
1. Footing size, depth and reinforcement is unknown.
2. Connection of the wood columns to the footing is unknown.
3. Quality of the wood columns is unknown.
4. Any other aspect on the load path that is unknown.

Then I would state that based on the above, no conclusion can be drawn by ANY ENGINEER as to the code compliance of the porch.

We are getting building inspectors baiting homeowners with requests for engineers to "certify" that things are OK. Sometimes its the engineers that end up getting baited into a position that they can't defend.

 

[racookpe1978]

Slide a crow bar or narrow (1 inch x 1/8 inch) flat plate down the side of the concrete: "Feel" when it stops scratching against concrete to get a feel for the concrete depth.

Not much else you can do short of a digging out the foundation (so you loosen it up) to figure out how big and wide and deep it is so you can tell some bureaucrat that it hasn't moved yet.

 

[Builder604]

Thanks for the input. JAE thats pretty much exactly what I was thinking.
racookepe1978 I thought about doing that however, with the post being set inside the perimeter 8" brick wall, i dont know how much that will help. However I may check the footing exposure and depth anyway.
Thanks again!

 

[XR250]

@ Builder604 I agree somewhat with JAE. Unfortunately, if you add too many disclaimers, the inspector may require some demolition of the existing structure to find out more.
I think your original statement is the way to go and get a contract from the homeowner limiting your liability.
BTW, I designed a church in Nash County about 12 years ago.

 

[a2mfk]

My experience with most porch additions is that they are nowhere near code, especially in terms of uplift. Even with moderate wind speeds, porch roofs, which are mostly overhangs as far as I am concerned, have considerable uplift forces. Unless you can inspect all of the connections and verify a proper load path, including that the foundation is OK in uplift, I would walk away from this project, as I have had to do with similar projects. Of course a porch roof foundation is going to be OK in terms of no visible signs of distress or settlement, there is practically no gravity load unless a crew is redoing the roof. But the wind can blow anytime...

Why did they only ask about the porch column footings, which are really the least concern? The most egregious mistakes with porches are usually the connection to the main structure. Many times they simply attach to the fascia or otherwise improperly tie into the edge of the roof structure.

 

[XR250]

@A2MFK, he could add some clip angles at the slab for uplift. Also, there is gravity load from snow - even in Nash County, NC

 

[Builder604]

There were many other comments from the building inspector that the GC will be correcting but the request for an engineers letter was only requested to "verify footings at posts are adequate".

 

[BAretired]

Unfortunately, you can't very that footings are adequate. Neither can anyone else.

BA

 

[CELinOttawa]

And the scope of "verify footings at posts are adequate" could be read to include almost anything, including a2mfk's Wind load/uplift concern.