AskCodeMan

Hi Jerry,
My question concerns being able to determine what type of foundation is in place on barrier islands and homes along the intercostal water way.
Are there any specific rules located in the code that address this or does the soil test and location determine what is designed?
I think I already know the answer to the next question but I'll ask anyway. Is there anyway to visually determine after construction if a piling foundation is installed? Thanks.

David

bigdog wrote:Is there anyway to visually determine after construction if a piling foundation is installed?

David,

Yes and no.

Yes, in that most of the houses with pilings and grade beams will have an entrance into the crawlspace under the house and, after entering the crawlspace you will see perimeter and intermediate grade beams which meet at the pilings. Sometimes the intermediate grade beams are not as deep as the perimeter grade beams and you can easily (sometimes not so easily) go under the intermediate grade beams to access adjacent crawlspace areas.

No, in that a rare few (rare that I have seen) do not have a crawlspace entrance and virtually no crawlspace. I have seen a few which had no crawlspace entrance, but, after going in through a hole under a perimeter grade beam made by the family dog, there was just enough space to slither ("slither" - intentionally used that word) under the floor to an intermediate grade beam (followed the dog burrow and under an intermediate grade beam).

It is quite common, in fact, more common than not, to find extensive concrete spalling on the grade beams and floors of houses built pre-1960's/70's as they frequently used unwashed beach sand in the concrete, even washed beach sand, before that. Even if they used proper clean sand in the concrete, the salt air environment can still cause spalling of the concrete.

I have also seen crawlspace where the access was down through a closet floor, and sometimes those crawlspaces were quite high, over 6 to 8 feet height in the crawlspace, so don't 'just drop down' without having a way back out - besides, sometimes the crawlspace floors are tidal in that the tidal waters rise and fall within the confines of the crawlspace.

Slab on grade is usually fairly easy to identify because the slab and monolithic footing is not very deep, i.e., a 4" slab, footing is typically a maximum of 12" below grade, finished floor level is typically 6" above grade, making the thickened monolithic edge 18" or so deep, thus the finished floor is not much higher than the walks/porches/patios leading to the entrance doors.

Footing and stem wall typically has a higher finished floor height, similar to pilings and grade beams, but the stem wall is masonry as compared to a poured concrete grade beam.

I have seen homes in Delray Beach on the canals circa 60's and 70's that appeared to be slab poured on top of piling with no crawl. The soil would be washing out from under the home due to leaks in the seawall but no structural damage. I thought all buildings on barrier islands were piling foundation?

I don't really think digging down and disturbing the termite treatment is wise so I will just have to report what I can see.

David

bigdog wrote:I thought all buildings on barrier islands were piling foundation?

Only the ones built by smart builders and architects ... those are typically still solid, the other ones are all cracked up due to settlement ... and some were really bad - I had one I recommended knocking down due to all the cracking and major structural damage because it was on a slab on grade with no pilings or grade beams.

I don't really think digging down and disturbing the termite treatment is wise so I will just have to report what I can see.

You wouldn't be digging anything out which was not already dug out (by animals, landscapers, etc) or destroyed by erosion.