About KEYSTONE
KEYSTONE was founded in San Francisco in 2009 by Marcus Holt, a former project executive who believed that the construction industry's persistent failure to deliver projects on time and on budget was a process problem, not a people problem.
Fifteen years later, KEYSTONE has delivered over 240 projects across the Bay Area — custom homes, estate compounds, commercial headquarters, flagship retail — with a 97% on-time delivery rate and a client retention rate that means roughly 60% of our revenue in any given year comes from past clients or their referrals.
Our Values
Craftsmanship
We write specifications, not assumptions. Every subcontractor on a KEYSTONE project receives a written scope of work that defines not just what they'll build, but how it will be built — materials, tolerances, sequencing, and inspection criteria. We hold the standard at rough frame, not at final walkthrough.
Safety
Safety is not a compliance exercise at KEYSTONE — it's a performance metric. We've maintained an EMR (Experience Modification Rate) below 0.72 for seven consecutive years. Every superintendent completes OSHA 30 before their first day on a KEYSTONE site. We have a zero-tolerance policy for shortcuts, regardless of schedule pressure.
On-Budget Delivery
97% of our projects close within 3% of the contracted GMP. We achieve this through obsessive pre-construction — a 15-year estimating database, documented allowances, written contingency strategies, and a change order process that never allows verbal agreements. We'd rather have a difficult budget conversation in pre-construction than a difficult one at 80% complete.
Our Team
Marcus founded KEYSTONE in 2009 after 12 years as a project executive with DPR Construction and a senior PM role at an award-winning design-build firm in Portland. He holds a Master of Construction Management from Cal Poly and has personally overseen more than $180M in residential and commercial work across the Bay Area. His insistence on pre-construction rigor — full MEP coordination, value-engineered structural options, and written schedule logic before a shovel turns — defines KEYSTONE's reputation.
Diane leads design-build projects from schematic phase through construction documents. She trained as an architect at UC Berkeley and spent six years with a residential architecture firm before joining KEYSTONE's integrated design-build model. Her portfolio spans hillside custom homes, historic renovations, and commercial interiors — always with a focus on material intelligence: how things connect, age, and read in 20 years.
Leo manages KEYSTONE's most complex active builds simultaneously, with a reputation for owning the schedule like a second set of blueprints. He came to the firm with a background in civil infrastructure — including two years on a bridge rehabilitation project — which gives him a structural intuition most residential PMs lack. Clients frequently mention Leo by name in post-project surveys.
Sarah runs KEYSTONE's pre-construction process: estimating, subcontractor qualification, constructability reviews, and permit coordination. She built the firm's estimating database from scratch and has driven cost certainty to within 3% of bid on 87% of projects over the last four years. Her background includes a decade in commercial bid management for a general contractor with $500M annual volume.
Tomás is on-site every day. He manages the field, coordinates all subcontractors, and enforces KEYSTONE's zero-defect policy at every rough inspection. He has been with the firm for 11 years, starting as a carpenter's assistant and earning every certification along the way. Trade partners respect him because he knows their work as well as they do.
Priya is the client's primary point of contact from signed contract through punchlist. She manages the permit process across five Bay Area jurisdictions, tracks all open items in KEYSTONE's project-management platform, and produces the monthly owner's report that every client calls 'the clearest communication I've ever received from a contractor.'
Work with us.
We take on a limited number of new projects each year so we can give each one the full weight of the firm.
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