AR Landscape cheat sheet

Under AIA A201 the contractor owns means, methods, sequencing, and site safety; the landscape architect's periodic site visits confirm general conformance and are not supervision.

Change order: signed by owner, contractor, and architect, and adjusts contract sum or time after pricing is agreed. Construction change directive: architect orders the work before agreement, setting a not-to-exceed amount.

An RFI requests clarification and changes nothing by itself; an ASI directs a minor change without altering contract sum or time; substitutions require formal written approval.

Additive alternates are accepted in the order bid until the budget is exhausted; deductive alternates are subtracted in the reverse order listed.

Retainage typically runs 5-10% of each pay application (AIA G702/G703) and is reduced or released at substantial completion; final payment follows punch list completion and final lien waivers.

Review of shop drawings and samples confirms design intent only; the contractor remains responsible for dimensions, quantities, field verification, and coordination of trades.

A one-year planting establishment or warranty period from substantial completion is typical; plants that fail for reasons other than owner neglect are replaced at no cost.

Design contingency benchmarks: roughly 10-15% at schematic design, 5-10% at design development, and 3-5% at construction documents.

Lump-sum contracts suit well-defined scope, unit-price contracts suit uncertain quantities, and cost-plus arrangements suit fast-track or unknown existing conditions.

Percent slope = (rise / run) x 100, so 2% equals 1 foot of fall in 50 feet; contours spaced closer together indicate steeper ground.

Public Land Survey System: a township is 6 x 6 miles containing 36 sections; each section is 1 square mile, or 640 acres. A USGS 7.5-minute quadrangle is drawn at 1:24,000.

Soil texture from the sand-silt-clay triangle, plus USCS or AASHTO classification, drives infiltration rate, bearing capacity, and plant suitability; percolation tests size septic absorption fields.

Hydric soils with gray colors and redoximorphic mottling signal wetland hydrology and usually trigger permits; FEMA Zone AE carries a published base flood elevation.

Zoning controls to inventory: setbacks, height limit, lot coverage, open space ratio, and floor area ratio (gross floor area divided by lot area).

Base-map inventory items: property lines, easements, utilities, topography, drainage patterns, soils, vegetation, climate, views, noise sources, and circulation.

Tree inventory records per individual: species, DBH at 4.5 feet, height, canopy spread, drip line, condition rating, and transplantability.

Analysis converts inventory into opportunity and constraint overlays (McHarg method) by mapping slope, hydrology, soils, vegetation, and access, then combining them.

Sun and shadow studies use solar azimuth and altitude for the project latitude; a wind rose gives prevailing direction and frequency for comfort and planting decisions.

Project sequence: program, concept, schematic design, design development, construction documents, bidding, then construction administration.

Space-making devices include edge, threshold, enclosure, focal point, hierarchy, sequence, and the prospect-refuge pairing of open views with sheltered places.

Planting layers are canopy, understory, shrub, and herbaceous or groundcover; mass species in drifts and repeat them through the plan to build unity.

Space plants at roughly 60-80% of mature spread for rapid cover; at 100% of mature spread there is no overcrowding but also no immediate effect.

Accessible route: 36-inch minimum clear width, 60-inch turning and passing spaces, running slope no steeper than 1:20, cross slope no steeper than 1:48, firm stable surface.

Accessible parking: 8-foot stall with a 5-foot access aisle for cars or an 8-foot aisle for vans; at least one in six accessible spaces must be van accessible.

CPTED principles are natural surveillance, natural access control, territorial reinforcement, and maintenance, applied to sightlines, entries, lighting, and ownership cues.

Wildfire defensible space: Zone 0 is 0-5 feet and noncombustible, Zone 1 is 5-30 feet lean-clean-green, and Zone 2 is 30-100 feet with reduced fuel continuity.

Hydrozones group plants by water use (very low, low, moderate, high) so valves and schedules match the plant water budget instead of irrigating uniformly.

Minimum grades: 1% with 2% preferred on turf and walks, about 2% on paving and swale flow lines, and a 5% slope away from buildings for the first 10 feet.

Contour lines never cross or touch except at a vertical face; evenly spaced parallel contours mean uniform slope, and closed hachured loops mark depressions.

Accessible grading: running slope no steeper than 1:20 (5%) and cross slope no steeper than 1:48 (2.08%); anything steeper becomes a ramp with landings and handrails.

Rational method peak flow Q = CiA, where C is the runoff coefficient, i is rainfall intensity in inches per hour, and A is area in acres; Manning's equation sizes channels and pipes.

Average end area volumes: V = (A1 + A2) / 2 x L; balanced cut and fill minimizes haul distance, import, and export of soil.

Swale standards: 1-2% minimum longitudinal slope, side slopes of 3:1 or flatter, with capacity and velocity checked against the lining (grass, riprap, turf reinforcement).

Retaining walls require drainage: washed gravel backfill, filter fabric, and weep holes or a perforated footing drain, because hydrostatic pressure is the usual cause of failure.

CSI MasterFormat divisions used most: 31 Earthwork, 32 Exterior Improvements, 33 Utilities. Specifications follow the three-part format of General, Products, and Execution.

Sheet order: cover and general notes, existing conditions and demolition, layout, grading, drainage and utilities, planting, irrigation, details, specifications; each sheet carries north arrow, graphic scale, and benchmark datum.