Sprinkler Break in a Closed Restaurant with No Heat

No. Two independent problems will keep this building wet.

Problem 1: the dehumidifiers are being rated at conditions that do not exist here. 130 pints/day is an AHAM rating at 80 F and 60 percent RH. At 62 F the refrigerant coil runs much colder, the unit's ability to condense water drops substantially, and frost or coil icing becomes a real risk. Expect a large fraction of rated capacity to disappear. Do not size from the nameplate - pull the manufacturer's performance table for the actual entering conditions and recalculate, and plan for more capacity or warmer air.

Problem 2: opening the building imports moisture. Outdoor dew point is 70 F; the interior is 62 F. Ventilating with that air delivers water vapor that will condense on every surface at or below 70 F - the slab, the LVP, the gypsum, the equipment. The dehumidifiers would spend their reduced capacity removing the outdoor load instead of the water in the building. "Letting air in" makes the loss bigger.

What to change:

• Close the building. Sealed, controlled drying, not ventilation.
• Add temporary heat to bring the space into the 75-80 F range. Warmer air lowers the interior RH, drives evaporation from the slab and gypsum, and restores much of the refrigerant units' capacity. This is generally cheaper than adding more dehumidifiers.
• Verify with a thermo-hygrometer inside and out and log it; confirm the supply air from the dehus is drier than the room air.
• If heat is genuinely unavailable, plan on desiccant dehumidification, which performs far better at cool temperatures than refrigerant units.

Class 3 by extent, with Class 4 behavior in the floor. The volume of water is large, it covered a big contiguous area, and it wicked 8 in into the gypsum - that is Class 3 territory. But the floor assembly is the real problem: LVP glued to a slab with a vapor retarder beneath means there is no drying path downward and the covering itself blocks evaporation upward. That is trapped moisture, Class 4 in practice regardless of the label.

LVP and slab:

• Remove the LVP in the affected area. Water is under the plank; the adhesive is compromised; and the slab cannot dry through it. Attempting to dry through the finished floor typically produces a slow, uneven result and a floor that later releases or tents.
• After removal, clean the slab, then dry it from the top. Because there is a vapor retarder beneath, the slab will dry only upward, which sets the schedule.
• Document that the LVP will not be reinstalled over a slab that has not met the flooring manufacturer's moisture limit.

Gypsum:

• Remove the wet cove base and cut a flood cut to at least the top of the wicking plus a margin, typically 12-24 in above the visible line, so the wall cavity and any insulation can dry. For clean supply water the cut is a drying decision, not a contamination decision.
• Remove wet insulation; do not leave saturated batts inside a cavity behind new drywall.

Slab drying: use air movers across the open slab plus the corrected dehumidification; monitor the slab with an in-situ RH probe rather than a surface meter.

Set the baseline before equipment runs, then measure the same points daily.

Baseline (day zero): a moisture map with thermal imaging and pin-meter readings on gypsum and any framing, slab readings via in-situ probes, photos of the water line, a sketched affected area, and indoor/outdoor temperature and RH. Record the class and category assumptions you are working under.

Daily:

• Temperature and RH inside, outside, and in the dehumidifier supply.
• Slab in-situ RH probes at the deepest accessible point, plus unaffected slab for comparison.
• Pin-meter grid on framing and drywall edges, read at depth.
• Psychrometric check: the drying chamber should trend toward a lower dew point, and wet materials should trend toward the dry standard set from unaffected material in the same building.
• Equipment run hours, water removal, and any change in conditions or scope.

If readings plateau:

1. Check the obvious first - equipment actually running, filters clean, coils not iced, power stable, building not being vented.
2. Re-check the psychrometrics: is the dew point coming down, or is the space simply cold and saturated? Add heat rather than air movers.
3. Look for moisture you have not exposed: adhesive under residual plank, wet insulation inside a closed cavity, water under equipment pads or casework, slab moisture outside the area you opened.
4. Add dehumidification capacity only after fixing conditions - more machines at 62 F mostly add heat and noise.
5. If progress still stalls, revisit the classification; a Class 4 element you treated as Class 3 will stall exactly this way.

Record the plateau and what you changed. The log is what makes the schedule and the invoice defensible.