Chapter 2 of 820% of exam

Subfloor Evaluation, Preparation, and Material Acclimation

About 20% of the C-15 exam covers removing old flooring, preparing and testing the subfloor, underlayments, acclimation and, new in 2026, moisture mitigation. This page is a short survey; the PrepPass C-15 study guide teaches each step with Cal/OSHA's asbestos rules and the manufacturers' moisture limits.

Removing old flooring

Vinyl and asphalt flooring installed no later than 1980 is presumed to contain asbestos under Cal/OSHA; it may not be sanded, dry-swept, ripped up or mechanically chipped outside a negative-pressure enclosure.

100 square feet

Asbestos-related work of 100 ft² or more needs a C-22 license or asbestos certification and a Cal/OSHA registration first.

B&P Code §7058.5; 8 CCR §341.6

Lead

Paid work disturbing paint in pre-1978 housing falls under EPA's RRP rule.

40 CFR Part 745, Subpart E

Moisture testing

Concrete is tested by in situ RH probes (ASTM F2170) or calcium chloride (ASTM F1869) at service conditions; the flooring or adhesive manufacturer sets the limit.

Lightweight concrete

Armstrong says not to use the calcium chloride test on lightweight concrete or fills.

Armstrong F-5061, Ch. 3

Example limits

Congoleum: 5 lb/1,000 ft²/24 h or 80% RH.

Congoleum installation guidelines

Acclimation and mitigation

Acclimation periods are product-specific; a slab over the limit is dried further or treated with a moisture remediation system, then bond-tested.

Primers

Primers are not designed to reduce moisture vapor emissions.

CRI 105 §8.8

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