e.1) Why don’t they use this type of piers for New Construction?
Because it doesn’t work. Even without knowing anything about engineering, if this system is so good, why not build houses and buildings with it from the get go? The system just doesn’t work, doesn’t meet code, that’s why it’s not used in the beginning, and that’s why no commercial buildings even use it for foundation repairs.
e.2) If the press piles system doesn’t meet code, why can I get a permit from the city?
Because the city doesn’t know… The building code is a very thick book, so the city government relies on engineers for the right answer in many instances. When it comes to structural engineering (which includes foundations) and Geotechnical Engineering (Soils), a lot of major cities (San Antonio, Austin, Dallas, Houston, Etc.) rely heavily on the Engineer. If you’ve read many of our other articles, you’d know that many residential engineers are in fact not structural or geotechnical engineers (and some get commissions from foundation repair companies…). So, a lot of stuff gets approved by the city without necessarily being right. Just because you get a permit from the city approving your foundation repair it doesn’t mean the foundation repair will work, or the foundation repair meets the code, and for that matter, it doesn’t even mean that it has been engineered.
e.3) Do concrete press piles foundation repair fail 100% of the time?
No. We don’t have the statistics on “failure”. We do know we are called often to go look at foundations that have been repaired using this type of foundation repair system. To be fair, we have been called on a few times where the foundation repair system moved but it wasn’t too significant, but created enough damage to cause some worries. There are a few instances where a concrete press pile, although still not meeting the code, could still work as far as gravity only loads is concerned.
For example, if there’s only a couple of feet between the bottom of the foundation beam and the rock stratum, it is possible that the change in volume in the expansive soil might no be enough to push the piles up; but you’d be taking a guess. Also, since the name of the game is to keep the moisture in the soil constant, if you have a house or building which is completely surrounded by parking or patios, then it may be possible that the moisture in the soil might not change significantly as to make the piles push up or down; but again, you’d be taking a guess.