Spec homes and custom homes are the same product on paper and almost nothing alike to manage. The framing is identical, the inspections are identical, the trades are identical. The project management overhead is roughly twice as heavy on a custom build, and the failure modes are completely different. Builders who run both kinds of work without adjusting their cadence, their staffing, and their draw structure end up with spec margins eaten by phantom client communication and custom clients who feel ignored.
The contrast below uses 926 Stratford as the spec example (1,784 SF, $430,250, Sweetwater TN, no buyer at the time of kickoff) and a hypothetical custom build of similar scope (a 2,100 SF custom on a family acreage, $580,000, with a buyer signed at contract). The two projects look the same from the framing inspector’s perspective. Everything else differs.
The headline differences
| Dimension | Spec (926 Stratford) | Custom (hypothetical) |
|---|---|---|
| Client communication | None during build, marketing-driven at close | Weekly, sometimes daily during selections |
| Selections workflow | Pre-decided by builder, no buyer input | Heavy, often 60+ decisions tracked individually |
| Change order frequency | Rare, usually internal value engineering | Expected, often 8 to 15 per project |
| Draw schedule | Front-loaded, milestone-light | Milestone-driven, often 6 to 8 draws |
| Timeline optimization | Speed, to reduce carry cost | Buyer satisfaction, to protect referrals |
| Team composition | PM + super, no client liaison | PM + super + dedicated client liaison |
| Warranty exposure | Standard residential, defect-driven | Higher, often expanded by contract terms |
Client communication cadence
On 926 Stratford the client communication during construction is zero. There is no client. The marketing photos go up at dry-in, the listing goes live around drywall, and the buyer arrives somewhere between paint and final. The communication overhead is replaced by listing maintenance and showing requests, which the sales side handles, not the construction side.
On the custom build, weekly is the floor. Most custom buyers expect Friday updates with photos, a one-paragraph summary of what happened that week, and a forward look at the next two weeks. The builders who skip the update get a Monday morning phone call from the buyer asking for one. The builders who deliver consistently get fewer phone calls, not more, because the buyer trusts the rhythm.
The cost of a weekly client update is roughly 90 minutes per project per week if it is templated and 3 hours if it is written from scratch. On a builder running five custom projects, that is the difference between half a day and two full days of overhead per week.
Selections workflow
Selections are where the spec/custom divide becomes operationally obvious. On 926 Stratford the entire selections package was decided by the builder before kickoff: cabinets in white shaker, quartz counters in a single neutral, LVP flooring in a specific SKU, plumbing fixtures from a single line. The selections sheet has roughly 40 entries and zero decision points open during construction.
On the custom build, the same 40 entries are decisions the buyer has to make, on a schedule, against deadlines that align with construction sequence. Cabinets have to be ordered six weeks before installation, which means cabinet selection has to close around dry-in. Tile has to be selected before drywall finish, which means roughly week 14. Plumbing fixtures have to be selected before the plumber returns for rough-in finish, which depends on the project sequence.
The selections workflow on a custom build is its own project plan running in parallel to the construction plan. Without it, the buyer misses a deadline, the trade waits, and the schedule slips by a week for every missed selection. On a custom build with no selections coordinator, expect 15 to 25 percent schedule slippage attributable to late selections alone.
Change order frequency
Spec change orders are rare and usually internal. The builder decides to swap a fixture line because the original is on backorder, or to move an outlet because the framer noticed a conflict. The change is priced internally, signed by the builder, and added to the project record without external approval.
Custom change orders are expected and external. The buyer asks for an additional outlet in the office. The buyer asks to move the laundry sink. The buyer asks to upgrade from the standard cabinet line to a custom shop. Each one is a priced change order with a buyer signature, a price impact, a schedule impact, and a payment trigger. A custom project that produces zero change orders is rare and usually means the scope was unusually well-defined or the builder is absorbing changes without billing them.
The volume of custom change orders is the single biggest argument for a dedicated client liaison. Processing 10 change orders without one is a part-time PM job by itself.
Draw schedule structure
Spec draws are usually front-loaded. The builder needs cash for the permit, the foundation, and the framing package, and the lender knows the project will sell at completion at a known price (or close to it). A typical spec draw schedule is four draws: foundation, framing/dry-in, rough-in/drywall, and final. Each draw covers a large milestone with clear visible completion.
Custom draws are usually milestone-driven and finer-grained. The buyer is paying as the work progresses, often with a construction loan in their own name, and the lender wants smaller draws against tighter verification. A typical custom draw schedule is six to eight draws: foundation, framing, dry-in, MEP rough, drywall, trim, finishes, final. Each draw is smaller, the inspection cadence is higher, and the documentation per draw is heavier.
The cash-flow implication for the builder is real. On a spec build the builder carries less of the work-in-progress because the draws come in chunks. On a custom build the builder is closer to even cash flow but carries more administrative overhead per dollar drawn.
Timeline optimization
Spec projects optimize for speed. Every day on the calendar is a day of carry cost: interest on the construction loan, property taxes, lot carry if the lot was held before construction. A spec build that finishes in 22 weeks instead of 26 weeks saves roughly 4 weeks of carry, which on $430,250 is $4,000 to $6,000 of pure margin.
Custom projects optimize for buyer satisfaction. A custom build that finishes in 26 weeks with the buyer happy is worth more than the same build that finishes in 22 weeks with the buyer feeling rushed through selections. The buyer is the source of referrals, the source of warranty patience, and the source of the next custom project. The timeline tradeoff is real and often runs against pure speed.
Team composition
On 926 Stratford the team is the PM and the superintendent. The PM runs the schedule, the budget, and the vendor relationships. The super runs the site. There is no client liaison because there is no client. The marketing side handles listings and showings, which is a separate function with no overlap to the construction team.
On a custom build, the same PM and super exist, plus a dedicated client liaison. The liaison runs selections deadlines, weekly updates, change order intake, and the buyer relationship. On a small builder the liaison is a half-time role; on a builder running 15 customs in parallel the liaison is a full team. Either way, the function exists because the construction PM cannot run the schedule and the buyer relationship simultaneously without one of them suffering.
Warranty exposure
Spec warranty is standard residential: 1 year workmanship, 2 years systems, 10 years structural in most states. The buyer takes the home as built and the warranty period starts at closing. The builder’s exposure is bounded by the contract and the standard warranty terms.
Custom warranty is often expanded by contract terms. The buyer negotiates extended warranty on specific systems, custom finishes that the builder did not source themselves, or vendor-supplied items where the buyer expects the builder to stand behind the vendor’s product. Warranty exposure on custom is materially higher than on spec, and the warranty walks (30, 60, 90, 365 days) often produce more items because the buyer has been engaged with the property for a year already and notices small things the spec buyer would never see.
What this means for tooling
Spec and custom both need schedule management, budget tracking, and photo documentation. Custom additionally needs selections workflow, change order workflow, client portal, and buyer-side warranty tracking. A builder running both kinds of work needs a tool that switches modes by project type, not a tool that forces every project into one shape. The cost of running a custom workflow on a spec project is wasted overhead. The cost of running a spec workflow on a custom project is a buyer who feels ignored.
The marketing photography difference
On a spec build, the marketing photography is a planned event near completion: a professional photographer shoots the staged home for the listing. The construction photo workflow is internal documentation for warranty and dispute purposes, and the marketing photography is a separate effort with its own budget line.
On a custom build there is no listing photography, but there is often a portfolio photoshoot at completion if the buyer agrees. The portfolio shoot serves the builder’s next custom marketing rather than the current project, and it requires the buyer’s written consent because the home is now their private residence rather than a marketed product.
The hidden costs of mixing the two without adjustment
Builders who run both kinds of work without separating the workflows run into a specific failure mode. The custom client expects spec margins and the spec project absorbs custom overhead. The PM running both projects defaults to the higher-touch workflow on every project, which means the spec project gets weekly photo updates that no buyer will ever read and the custom project gets a selections workflow that was never resourced.
The fix is to declare project type at creation and run the right workflow for each. A spec project should not generate selections deadlines. A custom project should not skip them. The PM’s cognitive load drops materially when the system takes a project type at the start and stops asking questions that do not apply.
Pricing and contingency differences
Spec pricing is a market exercise: the builder sets a sales price based on comparable sales, lot cost, build cost, and target margin. Contingency is built into the build cost (often 5 to 8 percent), and any contingency not consumed becomes additional margin at sale. The buyer pays the listing price; the builder absorbs the variance.
Custom pricing is a cost-plus or fixed-price exercise depending on the contract structure. Cost-plus passes overruns through to the buyer, which means contingency is the buyer’s problem, not the builder’s. Fixed-price keeps overruns on the builder, which means contingency has to be priced into the contract and defended through the build. Most custom contracts run fixed-price with allowances for selections, which puts the builder on the hook for build cost variance and the buyer on the hook for selection cost variance.
How BuilderGrid handles the difference
BuilderGrid sets project type at creation (spec or custom). On spec projects the buyer-facing modules (selections, client portal, change order intake) are hidden. On custom projects they are surfaced with deadlines tied to the construction schedule. Draw schedule structure and warranty terms are templated by project type and editable per project. The PM running both kinds of work sees the right tool for the right project without configuring each one from scratch.