A comment
Despite the almost unanimous admiration for screw piles, no no, and dissatisfaction will slip through, either the quality of work, then the material, or the construction of the foundation in general. It should be understood that screw piles are not a panacea and not a universal building material, but just one of them. For example, I have a gazebo on my site on such stilts and have been feeling fine for 5 years now. And the neighbor put on a pile an apartment building of 1.5 floors.
Not to mention the psychological effect, no matter how you look, the house is on “chicken legs”. In addition, twice a year, a neighbor crawls under the house and smears the steel shell of the piles with a kuzbaslak in places of contact with the ground. But under the surface of the soil they are not processed and are successfully rusting. Of course, there are technologies for replacing columnar foundations, but it is very expensive and it is better not to carry it out unless absolutely necessary.
pros
High speed construction
Suitable for most soils
Relatively low cost
Minuses
Susceptibility to corrosion