Helical Pile / Pier Deep Foundation
Trying to get more background information on these types of deep foundations. I am looking to build on a lot that has had extensive backfill on it. The geotechnical engineers drilled 4 holes around the lot and short version is that the top 8 to 10 feet of earth is not strong enough to support a structure. A structural engineer has suggested a crawl foundation, 4 feet deep and walls 18 inches wide with a lot of rebar. Additionally he is suggesting helical piles about every 6 or 7 feet under the base of the crawl space. The pipe on pile will be 8 inches across. This is all new to me but it looks like it is a rather common practice along shorelines, etc. The proposed house is a 2 story framed house, maybe 2000 square feet. If anyone has any insight to this type of construction technique, please advise. Thanks
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I've used them for deck foundations and they're magical. Talk to someone like TechnoMetalPost and see what they have to say.
Thanks, send them email. This structure is a cottage. The concrete foundation will likely weigh almost as much as house itself. I think my next move is check with building dept to see if piers alone can be used for support
Couple thoughts. Helical piles or push piers are good for this scenario. Spacing is typical. But 8 inch steel pipe? My god. You plan on landing helicopters on this house? I run into this many times with push pier and helical guys that go overboard on diameter, like they think these piers will one day see storm surge wave impacts. The piers are not going to buckle when there's a couple of tons of earth all around them.
I think the pier guys just get more money for the larger diameters. Seems like they're blatantly upselling them. The engineering math certainly doesn't support the need for them, that's for sure.