NCARB PDD - ARE 5.0 Project Development and Documentation Exam

Comprehensive Detailed Explanation with all NCARB ARE 5.0 Project Development and Documentation (PDD) Study Guide References:

In concrete technology, admixtures are used to modify properties of fresh or hardened concrete:

Air-entraining agents: Introduce microscopic air bubbles to improve freeze-thaw resistance; they do not increase slump.

Water-reducing agents: Reduce water content while maintaining slump; increase workability but only moderately.

Calcium chloride: An accelerator, speeds up setting time; does not increase slump.

Superplasticizers (also called high-range water reducers): Significantly increase the slump (workability) of concrete without adding extra water, making the mix more flowable and easier to place.

Thus, to greatly increase slump while maintaining water-cement ratio, the superplasticizer is the correct choice.

Supporting References:

NCARB ARE 5.0 Review Manual, Materials and Assemblies section

Portland Cement Association publications on admixtures

ACI (American Concrete Institute) guidelines on admixtures

When a GMP (Guaranteed Maximum Price) is established before the design is 100% complete and specific materials are not yet chosen, the correct approach is to specify allowances in the project manual.

An allowance is a fixed monetary amount for a specific scope item (e.g., flooring finishes) that allows the contractor to carry a cost in the bid/GMP until the actual product is selected. This ensures the GMP covers the item without delaying pricing.

A. Contingency — Is for unforeseen conditions, not specific unselected finishes.

B. Schedule of unit prices — Typically used for variable-quantity work, not for unknown product selection.

D. Alternate — Provides an option for substitution, but does not guarantee a base cost in the GMP.

PDD Reference: ARE 5.0 PDD “Project Manual and Specifications—Allowances, Alternates, and Unit Prices,” AIA A201 §3.8, CSI Division 01—General Requirements.

The scope involves interior renovation of an existing school reception office, limited to the footprint and protecting existing ceiling and fixtures. Additional staff is not proposed, and construction is during a defined 10-week summer break.

Plumbing is unlikely to require new or modified systems unless specified; not mentioned here.

Structural changes are not indicated since footprint remains same and no structural modifications are noted.

Mechanical changes would typically be required if HVAC or ventilation systems are altered, but the ceiling and fixtures (likely including diffusers) must be protected and are presumably left unchanged.

Electrical modifications are common in interior renovations to accommodate lighting, power outlets, communication systems, and potentially security or reception technology updates.

Thus, electrical drawings should be included to cover these updates.

Understanding the Problem

This question is about historic masonry restoration — specifically, repointing deteriorated mortar joints in soft-brick buildings.

Historic bricks, especially those made before the early 20th century, are often much softer and more porous than modern high-fired bricks. The mortar originally used was also softer, usually lime-based, which allowed for thermal movement, moisture permeability, and protection of the brick units.

Why the Correct Answer is “Duplication of Original Mortar Strength”

Best practice in preservation (as outlined in the Secretary of the Interior’s Standards for the Treatment of Historic Properties) is to match the original mortar in strength, composition, permeability, and appearance.

A mortar stronger than the original can cause the softer brick to crack or spall under thermal or moisture stresses, because the brick will end up being the weaker link and take the damage.

Duplication ensures that the new mortar works compatibly with the old masonry system — allowing for similar vapor transmission and structural flexibility.

Why the Other Options Are Incorrect:

B. Increased mortar strength over the original mortar — This is harmful in historic soft-brick construction. Stronger cement-based mortars can trap moisture in the brick, leading to freeze-thaw damage and spalling.

C. A bond stronger than the brick — This would cause the brick to fail first when stress occurs, which is undesirable in preservation work.

D. Deeper joint profiles — Deeply raking out joints unnecessarily can damage surrounding brick edges and change the visual proportions; repointing depth should only be enough to remove deteriorated mortar (typically 2–2.5 times the joint width).

NCARB ARE 5.0 PDD Study Guide References:

Content Area: Integration of Building Materials & Systems — Historic Preservation Techniques

Key Resources:

The Secretary of the Interior’s Standards for Rehabilitation & Illustrated Guidelines for Rehabilitating Historic Buildings

National Park Service Preservation Brief 2: “Repointing Mortar Joints in Historic Masonry Buildings”

Building Construction Illustrated — Masonry Restoration

Key Preservation Principle: “New mortar should match the historic mortar in composition, strength, and vapor permeability.”

When the mechanical unit on a utility mezzanine increases in size:

The structural engineer must confirm the mezzanine can support the increased weight and dynamic loads of the larger unit.

The architect coordinates with the structural engineer to ensure structural integrity.

The building owner is informed but not responsible for technical assessment.

The authority having jurisdiction (AHJ) oversees code compliance but not structural verification.

Accessibility consultant deals with accessibility issues, not mechanical equipment sizing.

In a tropical climate, the interior is cooler and drier than the hot, humid exterior. The vapor drive is from outside → inside, so the vapor retarder must be installed on the warm/moist side of the assembly, which is below the insulation when the insulation is above the roof deck. This prevents moist exterior air from reaching cooler surfaces inside the insulation where condensation could occur.

PDD Reference: Psychrometrics & vapor drive principles, PDD “Thermal & Moisture Protection—Placement of vapor barriers,” ASHRAE Handbook recommendations.

Sheet piling is a type of earth retention system used in excavations to prevent soil collapse. Reasons include:

D. When the natural soil slope is too steep to remain stable, sheet piling acts as a vertical barrier.

E. When soil cannot support itself during excavation, sheet piles provide lateral support.

F. When excavation is adjacent to a property line or existing structure and adjacent soil must not be disturbed.

Options A (grade beam support), B (raked shoring), and C (pile cap support) are not typical or primary uses of sheet piling.

With outdoor below freezing and indoor RH ~40% continuously, interior vapor will migrate outward. If a proper interior-side vapor barrier/retarder is missing, moisture moves through the wall and can condense and freeze at the cold exterior stone, forming visible ice. Insulation, air spaces, or rain screens help heat/moisture management, but the symptom (ice due to vapor diffusion) points specifically to the lack of an interior vapor barrier in a cold-climate assembly.

PDD references: Moisture control & vapor retarder strategy in cold climates; condensation diagnostics (ASHRAE Fundamentals; ARE 5.0 PDD—Envelope moisture control).

Mortar joint finishes impact water resistance and weatherability:

Concave joint is the most weather-resistant. The joint is compressed and curved inward, forming a dense, compact surface that sheds water effectively.

Weathered joint slopes outward but is less compact than concave.

Raked joint is recessed and can hold water, less weather-resistant.

Extruded joint protrudes and tends to trap water and dirt.

Therefore, concave joints provide the best weather protection.