Any other builder you find may not be as wise as the first builder.

Depending on the degree of hydrostatic pressure, even the basement floor might have to be waterproofed.

Since an engineer will be required in any case, approach the search from that point of view.

Ask your engineer for recommendations of builders capable of completing structures to his specs.

The excavation for the last house I completed--several hundred yards north of Lake Ontario--was visibly running water on "dry" days. A DMX membrane, weeping tiles and non-native backfill--sand and recycled concrete--did the trick.

Here's a description of what is usually sufficient to keep the water at bay.

Ah good times! This reminds me of our swimming pool excavation. See image. We are also in your area.

We needed a geotechnical engineer to approve everything that happened and spent a small fortune on extras to make sure we didn’t have issues.

Looking back at our correspondence with builder when our site was excavated an underground stream was found. They had to dig deeper and add more gravel as a result. We paid almost $30k more than was initially budgeted to manage it.

Money went to gravel around the home as backfill and waterproofing the foundation instead of damp roofing. It says they used a 40mm rubber membrane as well as superseal dimplemat. This is the link tiey sent us to show.

http://www.superprocoatings.com/Waterproofing.html

Here in the lower mainland soggy sites are extremely common and they are just dealt with.