Crestline Mechanical Plans / NFPA 37

Crestline Mechanical Plans (project spec exceeds code minimum)

Read against model code alone, 50 CFM intermittent meets the bathroom-exhaust minimum (IMC Table 403.3.1.1 / IRC M1505 set 50 cfm intermittent or 20-25 cfm continuous, with NO distinction between a full and a half bath) — so the contractor's 'meets code minimum' statement is technically true. The verdict fails on the CONTRACT DOCUMENTS, not the IMC: the Crestline mechanical plans specify 100 CFM for a full bathroom with a shower — a project requirement stricter than the code minimum — to handle the extra moisture from showering. Contract specs that exceed code are enforceable, so 50 CFM does not meet the design. The fan must be upsized or the duct run corrected to deliver the specified 100 CFM.

Crestline Mechanical Plans / IMC 401.4

Generator room exhaust must terminate a minimum of 10 feet above grade per the Crestline mechanical plans. At 8 feet, exhaust fumes containing carbon monoxide and diesel particulates are too close to pedestrian level and can be drawn into adjacent building openings.

Crestline Mechanical Plans / IMC 505

The range hood is underperforming by 70 CFM (26% below design). At 200 CFM, the hood does not provide adequate capture velocity at the cooking surface — grease-laden air and cooking fumes will escape the hood and spread through the unit. Common causes include undersized ductwork, excessive duct length, too many elbows, or a damper not fully open. The exhaust system must be corrected to deliver the full 270 CFM specified on the plans. Inadequate kitchen exhaust also affects the makeup air balance — the 300 CFM makeup air shaft will over-pressurize the kitchen if exhaust is only 200 CFM.

Crestline Mechanical Plans / SMACNA

A 10"x10" duct has only 100 sq inches of cross section. At 1,520 CFM, duct velocity would be approximately 2,190 FPM — far exceeding the 1,200 FPM maximum for occupied-space return ducts. The plans call for a 22"x22" RA duct (RA22X22-1520) with 484 sq inches providing approximately 450 FPM velocity.

Crestline Mechanical Specification

Wrong insulation type. While the thickness (0.5 inch) meets the minimum, mineral wool (PI-A) is unacceptable for refrigerant suction lines. The spec requires PI-B (elastomeric/rubber) because refrigerant suction lines operate below the dew point and will condense moisture from the surrounding air. Elastomeric insulation is closed-cell and acts as its own vapor barrier, preventing moisture from reaching the cold pipe. Mineral wool is open-cell and would absorb moisture, lose its insulating value, and cause corrosion on the copper suction line. The wet, degraded insulation would also drip onto equipment and ceiling tiles below.

Crestline Mechanical Specification / ASTM C1136

PVC jacketing is not permitted on outdoor pipe insulation per Crestline specifications. PVC degrades under UV exposure, becomes brittle, and cracks, allowing moisture infiltration that destroys the insulation. Aluminum or stainless steel jacketing is required for outdoor applications.