LARE Section 2 cheat sheet

Slope percent = (rise ÷ run) × 100; a 3-ft rise over 60 ft of run is a 5% slope.

Contour interval rule: 1–2 ft on slopes under 2%, 5 ft on rolling terrain, 10 ft on steep sites; smaller intervals on flat land reveal drainage patterns.

Scale selection: 1"=10' or 1"=20' for design details, 1"=40' to 1"=100' for site plans, and 1:24,000 for USGS base mapping.

DBH is measured 4.5 ft above grade on the uphill side; critical root zone radius is commonly estimated at 1 ft per inch of DBH (some specifications use 1.5 ft).

Web Soil Survey (SSURGO) reports drainage class, depth to seasonal high water table, hydric soil rating, and shrink-swell potential for preliminary planning.

Call 811 or the local one-call service before subsurface work; utility locations belong on the base map with horizontal and vertical datum notes.

NAVD88 is the current vertical datum; NGVD29 survey data must be converted before combining it with new survey information.

Summer solstice noon sun altitude = 90° − latitude + 23.5°; winter solstice altitude = 90° − latitude − 23.5°.

Slope classes: 0–3% flat with drainage limitations, 3–10% ideal for most development, 10–15% steep with grading cost limits, 15–25% severe, and over 25% generally unbuildable.

Rational method: Q = CiA, where C is the runoff coefficient (about 0.9 for pavement, 0.2 for lawn), i is rainfall intensity, and A is drainage area.

Aspect rule for the northern hemisphere: south- and west-facing slopes are warmer and drier; north- and east-facing slopes are cooler and moister; valleys collect cold air as frost pockets.

Suitability analysis: map each factor, assign weights, overlay the scores, then field-check the result before committing to a land-use plan.

Delineate watersheds by drawing lines perpendicular to contours along ridges and following flow paths to low points and outlets.

Stream and wetland buffers are set by local ordinance, commonly 25–100 ft of vegetated buffer; verify the jurisdiction rather than applying a default.

Viewshed check: sightline from eye height of 5–6 ft to the object; topographic screening works when an intervening ridge rises above that line.

Build an opportunities-and-constraints composite that separates developable ground from protectable resources before testing program fit.

Program sequence: needs assessment → space list with square footages → adjacency matrix → bubble diagram → blocking and stacking → scaled test fit.

Parking module: 9' × 18' standard stall; 8' accessible stall with a 5' access aisle; 11' van-accessible stall with a 5' aisle; typically 24' for a two-way aisle and 12–14' for one-way.

ADA: accessible route running slope maximum 5%; ramp maximum 8.33% with landings every 30 inches of rise; 60-inch turning space; 36-inch minimum clear width.

Fire apparatus access is commonly 20 ft clear width, 13 ft 6 in vertical clearance, and a 25–50 ft inside turning radius; confirm with the local fire marshal.

Grading minima: 1% in swales and paved areas with positive flow, 2% for turf, and 5% maximum on accessible routes.

FAR = gross floor area ÷ lot area; impervious coverage = impervious area ÷ lot area × 100.

Guardrails are required at drops over 30 inches; retaining walls over 4 ft typically need engineered design and permits.

Setbacks, height limits, and lot coverage come from zoning; confirm them before layout because they often define the buildable envelope.

Construction set order: cover sheet, general notes, layout and demolition, grading, drainage and utilities, planting, details, and specifications.

Line weight hierarchy: heaviest for cut or section elements, medium for visible edges, light for background, thinnest for dimensions and notes.

Every plan sheet carries a title block, north arrow, graphic scale, and revision block; the graphic scale survives reproduction while a written ratio does not.

Spot elevations are shown to 0.01 ft at grade breaks, inlets, corners, and finished floor; contours alone are insufficient for construction.

Planting plan legend content: botanical name, common name, size (caliper, height, spread), root type, spacing, and quantity.

Section cut lines on the plan must match section-drawing labels such as A-A and B-B and must show the viewing direction.

Scale conventions: 1"=10' to 1"=20' for details, 1"=20' to 1"=40' for site plans, 1"=100' for planning exhibits.

Bubble diagrams communicate adjacency before scale; test-fit plans then verify dimensions against code and program requirements.