Beefing up existing concrete footing

[TallPaulInJax]

Hello,
I have a single story block house I am considering adding a second story to. The house is located in Jacksonville FL on very sandy soil. The existing footing seems to be <= 16&quot; wide and possibly less (sloppily poured so it's hard to tell). The existing block wall rises approx 10.5 feet above the foundation. Prior to talking with a PE I would like to become more conversant about the following: What are the methods for beefing up an existing footing so it can support a second story? Piles and pile caps? Shoring up the foundation similar to this link?

http://www.preservation.org/foundation/

What are the relative costs, especially if I want to perform it myself under permit? Any suggestions appreciated.
Thanks
Paul

 

[VAD]

Hello TallPaulinJax:

I would suggest that you speak to the PE since this is a case where the loads and existing size of footing and characteristics of foundation soils interact. You may even find that the existing footing is adequate, but may not be the case as you seem to say it is sloppy.

You may need a couple of drill holes to detemine nature of foundation soils etc. Your PE if he is geotechnical with foundation design experience may be able to do entire asessment. In other cases you will have to seek structural help as well.

The methods for beefing up whether piles etc are chosen after this type of evaluation and aassessment are undertaken
Costs are then determined for the possible options.

Generalay, retrofitting is more difficult than starting from scratch and one needs to be careful.

Good Luck

 

[cap4000]

First thing I would recommend to you is get the soil strength properties. Then have a PE trace down the new loads from the new 2nd story. If you find out that the existing footing is No Good, I suggest &quot;Underpinning&quot; the existing footing before piling. There are contractors that specialize in deep foundation underpinning, but 1st get the foundation designed by a Licensed Strutural Engineer.

Good Luck.

 

[TallPaulInJax]

Thanks for the responses.

 

[cbosy]

We used chemical grout in a job in Lakeland, FL to turn sand into a sandstone like consistency to increase the bearing capacity under the footing in a case just like yours.

 

[TallPaulInJax]

Thanks, cbosy. Can you give me the name of the grout or a link to it's installation? Also, an idea on the price? After reading your note, I looked around and it seems like jet and chemical grouting require fairly elaborate systems to install, correct?
Thanks
Paul

 

[cbosy]

See if Foundation Services in Orlando, Fl are still around. The chemical grouting just involves advancing small diameter pipes slanting under the footing in the ground and injecting a sodium silicate based grout. It did not appear to be rocket science when I saw it performed as a very green engineer in 1986. I have a diagram we drew up and could fax it to you if you want.

 

[TallPaulInJax]

They seem to still be around:
Foundation Services Inc
(407) 228-7886 1315 E Michigan St
Orlando, FL

I'll give them a shout. If you get a chance, you can fax the diagram to my 800#: 877-576-2306. Thanks for the info!
Paul