The decisions are made: build the REV 2 (void-box) foundation Dunaway's engineer calls superior, with Keystone Concrete Placement (Stewart Builders) placing the concrete and Cantsink installing the helical piles. This page is the working file — why, the numbers, who's who, what to do next, and the questions to answer before signing.
Asked directly which revision to use, Dunaway's engineer of record said both are sound — but REV 2 is the superior foundation system. We're building to his recommendation.
Why the void box is the stronger system here. The house sits on helical piles either way. The difference is what's directly under the slab on this expansive-clay lot. In REV 2 the structural slab and grade beams are suspended over a void (collapsible carton forms): when the Houston clay swells, it expands up into that empty space instead of pushing on the foundation. Nothing about the structure's performance depends on imported fill or how well it was compacted.
That's why the engineer calls it superior — the most robust, fully-isolated approach to expansive soil. REV 3's select-fill pad is cheaper and faster, but its performance leans on fill quality and compaction. For a home you can't redo, paying a modest premium for maximum heave protection — on the engineer's recommendation — is the right trade.
We re-checked the REV 2 PDF title blocks: the REV 2 set is already an "Issued for Construction" set. Its revision ladder reads … Rev 0 = HOA Permit Set (the only line marked "not for construction"), then Rev 1 (04/06/2026) = "Issued for Construction," then Rev 2 = "Revised per client comments." So the "not for construction" wording you may have seen is just the older permit-set line in the history — not the current status. You are not waiting on an IFC release. The only thing to confirm with Dunaway is that REV 2 (not REV 3) is the governing set to build, since he later issued REV 3 as an option — see the next steps.
The one difference, in plain terms. Same piles, same grade beams, same engineer in both revisions. Only the under-slab system changes:
Keystone's $299,483 already contains the Cantsink helical piles. Once you split it, two things become clear: the piles are a fixed pass-through, and the real all-in is still missing three excluded items.
$299,483 is concrete + piles only. Keystone's proposal explicitly excludes void boxes under grade beams — yet the REV 2 structural detail requires grade beams cast on carton void boxes — plus all site work and spoil haul-off. Those have to be priced in before $299,483 is a real all-in. (Murat's table once showed Keystone at $312,753 using KGW's $13,270 line, but that was the REV 3 select-fill pad scope — REV 2 has no pad, so the REV 2 site-work number still needs its own quote.) Action: get Keystone to re-issue a single, gap-free REV 2 number.
Both bidders priced the exact same Cantsink proposal (06/16/2026), so the piles aren't a variable — they're a fixed $86,700 pass-through inside whoever pours the concrete. Here's what that buys:
Murat's read: Keystone will contract Cantsink directly, which means you may not be able to pull Cantsink's PE/sealed design or talk to them directly. So don't rely on a direct line — make the documentation a contract deliverable from Keystone: require Keystone to furnish Cantsink's sealed/PE-stamped pile design (per ESR-1559), torque logs, pile-installation reports, and closeout package. Also nail down in writing who absorbs the $28/ft charge if piles must go past 17 ft, and that Cantsink gets the engineer's geotech report it requires.
The case, in one breath. On a foundation you can't redo, you want a counterparty you can verify and terms that keep your leverage. Keystone is the trade name of Stewart Builders, Inc. — a 33-year-old, ENR-ranked firm (~$682M regional) that owns its own pump fleet — and it bills monthly in arrears with no large deposit.
The conditions that come with it. Contract the legal entity "Stewart Builders, Inc." Close the REV 2 scope gaps above. Get references on comparable new-construction custom-home helical foundations specifically — residential is Keystone's secondary line — and note the 2022 OSHA fatality on its record (resolved). All of that is in the next steps and questions below.
Run through public records — Texas SOS/Comptroller, BBB, OSHA, ENR, ICC-ES — and independently fact-checked. Three firms: the concrete builder, the pile sub, and a possible site-work sub.
REV 2 is already a construction set, so you're closer than it looks. The work left is contractual: confirm the set, close Keystone's scope, and lock the documentation.
REV 2 already reads "Issued for Construction" (Rev 1), revised by Rev 2 — no IFC release is pending. Just get Dunaway to confirm in writing that REV 2 (Rev 2, 06/04/2026) governs over REV 3, plus the one-paragraph "REV 2 preferred & why" note for the file/lender. Verify nothing on the County/HOA permit side needs the structural set re-submitted.
→ Dunaway · Juan Gonzalez, PEHave Keystone re-issue one number that resolves the grade-beam void boxes, site work, and spoil haul-off it currently excludes — so $299,483 becomes a true all-in. Confirm the contract names Stewart Builders, Inc. Their 15-day proposal has lapsed, so a refreshed one is needed anyway.
→ Keystone · Scott LoweSince Keystone contracts Cantsink, you won't deal with Cantsink directly. Put it in the Keystone contract: Keystone furnishes Cantsink's sealed PE pile design (ESR-1559), torque logs, installation reports, and closeout package — and define who eats the $28/ft overrun if piles exceed 17 ft. Make sure Cantsink receives the geotech report it requires.
→ Keystone (passing through Cantsink)REV 2 still needs site scrape, rough grade, and spoil haul-off. Re-quote KGW (or an alternative) for the actual REV 2 scope — not the REV 3 pad — and decide whether Keystone carries it or you contract it directly. Confirm proof-roll/subgrade tolerance before Keystone starts.
→ KGW / grading subCertificate of insurance (GL + workers' comp, owner as additional insured), references on comparable custom-home helical foundations (confirm the 46 & 54 Aria Isle jobs), written warranty, and a milestone-based payment schedule. Pull a live Comptroller Certificate of Account Status for Stewart Builders, Inc.
→ KeystoneThe bid excludes testing. Decide who arranges and pays for pile torque/installation verification and concrete cylinders, and confirm Dunaway's construction-observation role. Budget it now so it isn't a surprise change order.
→ Owner + Dunaway + testing labGrouped by who to ask. The ones that close real gaps in the REV 2 path come first.