Housing, Interiors, and Environmental Design
Domain 5, Housing, Interiors, and Environmental Design, tests housing decisions and affordability, mortgage and lease basics, space planning and clearances, design elements and principles, color theory, lighting, universal design, and sustainable practice. Items often present a client brief and ask for the choice that best fits function, budget, and safety.
Housing and finance
- Affordability benchmark: principal, interest, taxes, and insurance (PITI) at or under 30% of gross monthly income.
- Fixed-rate mortgages lock the rate; ARMs start lower and adjust. Discount points are prepaid interest that lowers the rate. PMI is typically required below 20% down.
- Lease terms to check: security deposit, rent escalation, subletting, maintenance duties, and the implied warranty of habitability.
Design fundamentals
- Elements: line, form, space, texture, color. Principles: balance, rhythm, emphasis, proportion and scale, harmony and unity.
- Color schemes: monochromatic (one hue), analogous (adjacent), complementary (opposite), split-complementary (either side of the complement), triadic. Value is lightness; intensity is saturation.
- Lighting layers: ambient, task, accent. A 30-inch counter needs task light because ambient alone casts shadows.
- Work triangle: sink, range, refrigerator; each leg 3–9 feet, sum 12–26 feet.
- Clearances: 36-inch minimum circulation path; 42–48 inches of aisle in a one-cook kitchen.
Sustainability and accessibility
- Universal design's seven principles include equitable use, flexibility, simple and intuitive use, perceptible information, tolerance for error, low physical effort, and size and space for approach.
- Green design: low-VOC finishes, daylighting, efficient appliances, durable materials, indoor air quality, reduced embodied energy. LEED is a rating system and ENERGY STAR a labeling program; neither is a code.
- The Fair Housing Act bars discrimination by race, color, religion, sex, disability, familial status, and national origin, and drives multifamily accessibility rules.
Worked example
A household earns $5,000 gross monthly. Taxes are $200 and insurance $75; PMI is $100. What loan can they carry at 30%? Reasoning: 0.30 × $5,000 = $1,500 for PITI. Subtract $375, leaving $1,125 for principal and interest. At roughly $6.00 per $1,000 borrowed (6%, 30 years), the loan ≈ $1,125 ÷ 6.00 × 1,000 = $187,500.
Traps that cost marks
- Calling a scheme complementary when it is split-complementary.
- Counting the dishwasher or microwave as a work triangle leg.
- Treating ENERGY STAR as a mandatory building code.