Pr3ciseArticles · Cost estimating
How Construction Cost Estimating Saves Money on a South Florida Job
The savings aren't in what the estimate costs. They're in the change order you don't write, the material you don't buy twice and the pay app that covers what you already spent. Where the money shows up, line by line.
Construction cost estimating reads like an expense on the front end: one more fee before anybody mobilizes. The savings aren't in what the estimate costs. They're in what it keeps from happening later: the change order you don't have to write, the material you don't buy twice, the pay app that actually covers what you already spent.
This article isn't about what goes wrong when the number is wrong; we cover that in the risks of an inaccurate construction estimate. It's about where the savings show up, what the data behind them looks like, and what each control is worth before you sign, with South Florida jobs in mind.
The savings aren't in the price. They're in what nobody took off.
Cost growth isn't bad luck. In a study of 258 transportation infrastructure projects, Flyvbjerg, Holm and Buhl (2002) found costs were underestimated on almost 9 out of 10 projects, with actual costs averaging 28% above estimate. The uncomfortable part is the rest of the finding: underestimation hadn't improved in 70 years.
A 70-year bias doesn't get fixed with experience or optimism. It gets fixed with definition. AACE International's estimate classification system (RP 18R-97, written for the process industries) puts a concept-screening estimate, prepared with 0-2% of the project defined, in a range of -20%/-50% to +30%/+100% against actual cost. A Class 1 estimate, built from unit costs and a detailed takeoff at 65-100% definition, narrows to -3%/-10% and +3%/+15%. Same project, same estimator. What changed is how much was measured.
Narrowing that range is the savings. The goal isn't a cheaper number. It's a number that resembles what you're going to pay. Everything between the two comes out of somebody's pocket.
Where the money actually shows up
Define the scope before you commit the budget
The cheapest hour on any job happens at a desk. Using Construction Industry Institute data from 78 building projects, Wang and Gibson (2002) compared projects with a well-defined scope at budget authorization against poorly defined ones. The well-defined projects finished 2.6% over budget and 2.7% behind schedule. The poorly defined ones: 12.9% and 20.9%. Ten points of cost and eighteen points of schedule, decided before anyone breaks ground.
Take it off once so you don't pay for it twice
Work that wasn't quantified still gets built, it just gets bought worse: late, at spot pricing, and sometimes twice. Using data from 359 CII projects, Hwang and colleagues (2009) put the direct cost of field rework alone at around 5% of total construction cost. The UK's Get It Right Initiative goes further: once unrecorded waste, latent defects and indirect costs are counted, it estimates errors cost between 10% and 25% of project cost, roughly seven times the industry's annual profit.
Price the change before the crew builds it
A change priced before it's executed costs what it costs. Built first and argued later, it costs that plus the drag on every crew still working. Working from a database of 226 projects, Ibbs (2012) measured average change of 8% and found roughly 40% of projects ran more than 10% change. When change stayed at 5%, labor productivity beat plan on 60% of projects. Once it passed 20%, productivity never reached the planned rate.
South Florida: what the code adds to the number
A takeoff priced off a generic national assembly will miss money in Miami-Dade, because the assemblies are different. Most of South Florida sits in the High-Velocity Hurricane Zone, and the HVHZ provisions of the Florida Building Code drive real quantities: impact-rated openings, roof attachment and secondary water barriers, corrosion-resistant fasteners, anchorage and uplift connections, shutter or protection systems. None of that is a line you add at the end. It changes the unit cost of the assembly itself.
Product approval is the second place estimates drift. If an assembly you priced doesn't carry a Miami-Dade Notice of Acceptance or a Florida Product Approval valid for the HVHZ, it won't survive plan review, and the substitute rarely costs the same. Permitting and inspection sequencing with Miami-Dade or the city of jurisdiction also belongs in general conditions, not in a mental note. That's why we run trade-level takeoffs for concrete and masonry, electrical, plumbing and fire protection separately, then reconcile the seams between them in a combined MEP estimate.
Pricing age matters just as much. According to the AGC (2026), input prices for new nonresidential construction rose 7.1% between June 2025 and June 2026, about double the 3.5% rise in contractors' bid prices, which means contractors were absorbing most of the increase. Over a longer window, AGC chief economist Ken Simonson reported nonresidential input prices up 39% between February 2020 and February 2024, nearly double the 20% rise in consumer prices. An estimate carrying last year's unit costs is already short before the first submittal.
Contingency you can defend
Contingency isn't a rounding up or a hidden markup. It's a number that answers a specific project's risk. The U.S. General Services Administration, which builds and renovates federal buildings, applies 7% construction contingency on new capital construction and 10% on repair and alteration work, while stating contingency should reflect each project's level of risk. If your takeoff is short by more than that, the contingency is gone before the first real unforeseen condition.
The UK Treasury reaches the same place from the other direction. Its optimism bias guidance tells public bodies to uplift capital cost estimates by up to 24% for standard buildings, 51% for non-standard buildings including refurbishments, 44% for standard civil engineering and 66% for non-standard civil engineering at outline stage. The relevant part for a contractor: that uplift only falls toward 2-6% as project-specific risks are identified and managed. Identifying them is exactly what a detailed estimate does.
Buying the job is not saving money
There's one kind of savings that isn't. In a study of highway paving contracts, Bajari, Houghton and Tadelis (2014) estimated that adapting incomplete contracts after award, through renegotiation and changes, costs 7.5% to 14% of the winning bid, far more than what bidders make on markups. In Italian public works, Decarolis (2014) found at least half the savings from awarding at the lowest price were lost to renegotiation afterward. An owner who takes the low number without checking what's in it usually pays the difference later, with less leverage.
What each control is worth on a hypothetical $2 million job
A hypothetical example, with the arithmetic shown. Take a $2,000,000 build. Our fee is flat: 250-400 EUR for a single trade, 800-1,000 EUR for a complete multi-trade estimate, which puts the full estimate under one tenth of one percent of that job. Applying the figures above to the same $2,000,000: Ibbs's 8% average change is $160,000; the 5% direct rework cost from Hwang and colleagues is $100,000; GSA's 7% new-construction contingency is $140,000; and the Get It Right Initiative's 10-25% error range is $200,000 to $500,000. The estimate pays for itself if it prevents a fraction of a percent of drift.
| Control before you sign | What it prevents | Reference |
|---|---|---|
| Scope defined before budget authorization | Double-digit cost and schedule growth | 2.6% vs 12.9% over budget (Wang and Gibson, 2002) |
| Detailed quantity takeoff by line item | Scope discovered in the field, and rework | About 5% of total cost in direct rework alone (Hwang et al., 2009) |
| Current unit costs with buildups | An estimate that's stale on bid day | Inputs up 7.1% vs bid prices up 3.5% (AGC, 2026) |
| HVHZ assemblies and approved products priced as such | Substitutions and rework after plan review | Florida Building Code HVHZ, Miami-Dade NOA |
| Contingency sized on identified risks | A cushion that covers nothing | 7% new construction, 10% repair and alteration (GSA, 2024) |
| Changes priced before they're built | Lost crew productivity | Past 20% change, productivity never hits plan (Ibbs, 2012) |
What a bid-ready estimate has to carry
Not every estimate saves money. The ones that do share four things:
- Quantities traceable to the drawings, so any number can be checked against the sheet it came from instead of somebody's memory.
- Unit-cost buildups per line item: material, labor, equipment and production rate, so you can see where every dollar comes from. You can see how ours look in our sample estimates.
- Current market pricing, dated, not last year's numbers carried forward.
- No allowances standing in for scope. An allowance is a gap with a number written on it, and gaps between trades are where change orders are born.
How we work
Pr3cise is a remote estimating office that prepares cost estimates and quantity takeoffs for GCs, specialty contractors, developers and architects, including teams building in Miami-Dade and the rest of South Florida. Send the plans, plus your quantities if you have them, and you get a line-item estimate with unit-cost buildups and current pricing in Excel and PDF, typically in 24 to 72 hours. Our estimating and takeoff service is priced per trade or per project, and the local scope is covered on our Miami construction estimating page.
If you want the other side of this first, read the ways a construction project gets ruined. If you have a bid or a loan in motion, request an estimate.
Frequently asked questions
It depends on what it prevents, not on what it costs. The public benchmarks set the scale: Ibbs (2012) measured average change of 8% across 226 projects, Hwang and colleagues (2009) put direct field rework at around 5% of total construction cost, and the UK's Get It Right Initiative estimates errors cost 10% to 25% of project cost. On a hypothetical $2 million job, that 8% is $160,000 and that 5% is $100,000. Our flat fee is 800-1,000 EUR for a complete multi-trade estimate.
As accurate as its level of definition allows. Under AACE International's classification system (RP 18R-97, written for the process industries), a concept-screening estimate prepared with 0-2% of the project defined runs from -20%/-50% to +30%/+100%. A Class 1 estimate built from unit costs and a detailed takeoff at 65-100% definition narrows to -3%/-10% and +3%/+15%. Expecting Class 1 accuracy from Class 5 information isn't rigor, it's an impossible standard.
It means the assemblies are not the generic national ones. Most of South Florida falls inside the High-Velocity Hurricane Zone, and the Florida Building Code's HVHZ provisions drive impact-rated openings, roof attachment and secondary water barriers, corrosion-resistant fasteners and uplift connections. Products also have to carry a Miami-Dade Notice of Acceptance or a Florida Product Approval valid for the HVHZ. Pricing a non-compliant assembly means a substitution after plan review, and substitutions rarely cost the same.