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.