If I remember correctly the treatment doesn't go in the soil but on the slab. Of course that was over 2 years ago so I may be remembering it wrong. I know here in SW FL termite treatment is required by local code.

You'll need to check the building code to see what may be required in your locality and with your builder to see what is best practice irrespective of building code requirements.

In our (coastal VA) area, we have the option of soil poisoning (yes, there is residual chemical in the soil, cpartist) or treating the first 3 ft +/- of framing materials with a borate-based termite treatment.

Not required where I am, but the house we tore down was almost condemned due to termite damage from crazy old lady who deferred all maintenance for about 20 yrs. We had it done for peace of mind knowing that our lot is termite prone, yet out west of town (where all the new development is) none of them do it.

Yes, yes, yes, we are currently dealing with termites after we "missed" our opportunity. We had a large addition added to the back of our home, huge patio that spans the whole back of the home, and completely new driveway (poured to the whole length of 1 side of our home). Our home in in south central PA, and I didn't realize that termites could be an issue here. We didn't know about treating before the cement/addition went in, and are currently kicking ourselves. There is a termiticide that can be saturated into the soil before your slab, or around a block foundation is poured/installed that will create a barrier for approx. 8-12 yrs if left undisturbed. (Lookup Taurus SC or Termidor) The main ingredient is the same thing that is in frontline for pets. So yes, it is soil-poisoning, however it is not agent orange. Then you can also go a step further and have a treatment sprayed or brushed onto the wood closest to foundation and lower floor joists that contains boron such as Bora-care, to protect the wood from all sorts of wood eating bugs. This site offers a bunch of good info (even if you do not want to do diy) https://www.domyown.com/

Termiticidal treatments are required in some parts of the Toronto core for new homes; I was required to use it under the footings only.

As a mortgage examiner/lender, we always require a termite inspection in suspect locales. While foam insulation is very effective in sealing rims in homes, it also provides a comfortable hidden habitat for termites.

Has anyone considered a physical (non-chemical) termite barrier?

This Univ of Florida report recommends Termimesh

http://blogs.ifas.ufl.edu/news/2003/08/12/uf-experts-say-termite-resistant-construction-best-way-to-prevent-damage/

This article has other suggestions:

Ask an Expert: How to help reduce chances of termites invading a home

https://www.mercurynews.com/2008/05/09/ask-an-expert-how-to-help-reduce-chances-of-termites-invading-a-home/