Terrazzo is the trade that suffers most from compressed project schedules. Submittals get short-circuited, slabs don't get the dry time, overhead trades aren't finished, and the GC asks the installer to make up time the project gave away upstream. This guide is a working schedule the GC can defend against the rest of the project.
The terrazzo timeline, working backwards
From the day the floor is needed substantially complete, here's the backward timeline:
| Week | Activity |
|---|---|
| TCO -1 | Final polish, seal, walk-through, owner training |
| TCO -2 to -3 | Grind through grit sequence (40→80→120→200→400→800→1500) |
| TCO -3 to -4 | Pour and initial cure |
| TCO -4 to -5 | Divider strip layout, substrate primer, mock-up final approval |
| TCO -5 to -7 | Substrate prep — shot blast / grind, moisture test, repairs |
| TCO -7 to -10 | Mock-up approval, color/aggregate samples |
| TCO -10 to -16 | Submittals approved (samples, shop drawings, product data) |
| TCO -16 to -20 | Specification complete, bid awarded, submittals begun |
The total from spec-complete to substantial-complete is 16–20 weeks for typical commercial terrazzo. Tenant improvements and renovations can compress to 10–12 weeks when substrate is known and ready. New construction routinely takes 20+ weeks because the substrate and overhead trades aren't ready on the early schedule.
Submittal package
The submittal turn is where most projects lose two weeks. Items required:
- Product data and manufacturer's installation instructions for matrix and primer.
- Mill certificates for aggregate (source, sieve analysis, weight per cubic foot).
- Sample boards: 3 each of approved color/aggregate blends, plus 2 variants per blend.
- Shop drawings: divider strip layout overlaid on floor plan with column lines and slab joints.
- EPD and HPD documentation (for LEED projects).
- VOC content certification (CDPH Std Method v1.2).
- Installer NTMA membership and project reference list.
- Mock-up location plan agreed with GC and architect.
- Warranty terms (manufacturer + installer).
The trades that must finish before mobilization
This is the schedule fight on every commercial project. Terrazzo cannot mobilize until overhead and adjacent work is complete:
- Overhead MEP rough complete and pressure-tested. No more pipe-fitting overhead.
- Ceiling grid installed and grid-paint complete. No more dust drops.
- Spray fireproofing complete and dry. Overspray is a terrazzo killer.
- Drywall installed, taped, and primer-painted. Joint compound dust falls into wet pours.
- Permanent HVAC operational (not temporary heat). Maintains 60–85°F and RH <75% through cure.
- Slab moisture testing complete with passing results.
- Adjacent walls protected with floor-to-ceiling poly or rigid board.
Pour sequencing
Large floors are poured in panels, defined by the divider-strip layout. Sequencing follows a few principles:
- Pour the largest contiguous areas first; pour around columns and irregular shapes second.
- Maintain wet edges within the same day's pour to avoid cold joints in a single visual field.
- Stop pours at divider strips, never mid-field.
- Plan grind-and-polish equipment access. The largest grinders need 6'+ clearance and corner access.
- Schedule cure-protection (rosin paper or breathable kraft) immediately after grout coat application.
Cure and protection windows
| System | Pour to grind | Pour to traffic | Pour to final acceptance |
|---|---|---|---|
| Epoxy terrazzo | 16–24 hours | 5–7 days | 10–14 days |
| Cementitious bonded (TM-2) | 5–7 days | 10–14 days | 21–28 days |
| Monolithic (TM-3) | 5–7 days | 10–14 days | 21 days |
| Sand-cushion (TM-1) | 5–7 days | 14 days | 28 days |
These windows assume controlled interior environment (60–85°F, RH 50–75%). Outside the band, all numbers extend.
Common schedule failures
- Substrate not delivered on the agreed date. Drywall finishing slipped two weeks; terrazzo gets two weeks less.
- Moisture test came back high; no contingency for mitigation in the GC's schedule.
- Overhead MEP was 'mostly done' but the spray fireproofing crew comes back during the pour.
- HVAC commissioning skipped permanent heat in favor of temporary; humidity isn't controlled.
- Mock-up was 'going to happen' but never did; architect now wants changes at the production pour.
- Adjacent trades scheduled to overlap. Painters and drywall finishers walking on freshly poured terrazzo.
Frequently asked
Can terrazzo go in before drywall finishing?
+
Strongly recommended against. Joint compound dust falls into pour and grinding operations and creates patches in the field. The schedule pressure to do this never pays off — patches and rework cost more than the saved overlap.
What's the fastest practical schedule for an epoxy lobby (3,000 sf)?
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10 days from substrate-ready to substantial-complete, assuming overhead is clean and the mock-up was approved in advance. Below that requires shortcuts that risk warranty.
Who owns the schedule if moisture test fails?
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Industry standard: the GC owns slab condition. Either the schedule absorbs the mitigation work or the owner authorizes a change for the slab not being delivered to spec. The terrazzo trade should not be asked to compress to make up for it.