LARE cheat sheet

Slope suitability thresholds: 0-4% suits active recreation and accessible walks; 4-10% suits lawns and paths with erosion control; 10-25% requires terracing, steps, or heavy planting; above 25% is generally unsuitable for development without engineered structures.

Solar noon altitude = 90 degrees minus site latitude plus solar declination, where declination is +23.44 degrees at the June solstice, 0 degrees at the equinoxes, and -23.44 degrees at the December solstice.

A dense tree or shrub windbreak reduces wind speed roughly 50 percent at 2 to 5 tree heights downwind, with measurable shelter extending 5 to 10 tree heights.

Accessible route limits: running slope maximum 1:20 (5%), cross slope maximum 1:48 (2.08%), clear width minimum 36 inches (915 mm), with landings where rise exceeds 30 inches.

Ramp limits: maximum slope 1:12, maximum rise 30 inches per run, with a 60-inch-long landing at the top, bottom, and any change of direction.

Wheelchair turning space is a 60-inch-diameter circle or a T-shaped 60-by-60-inch area; an accessible car stall is 8 feet wide beside an 8-foot access aisle, and van-accessible stalls need an 11-foot aisle.

Planning efficiency: net assignable area divided by gross building area typically falls between 0.75 and 0.85, with circulation, structure, and mechanical space consuming the remainder.

Design phase sequence: programming, schematic design, design development, construction documents, bidding and negotiation, then construction administration.

Drawing scale conventions: site plans at 1 inch = 20 or 30 feet, grading and utility plans at 1 inch = 20 to 40 feet, and details at 1 inch = 1 foot or 3/4 inch = 1 foot.

MasterFormat organizes specifications by work-result divisions, for example Division 31 Earthwork, Division 32 Exterior Improvements, and Division 33 Utilities.

SectionFormat divides each specification section into Part 1 General (references, submittals, quality assurance), Part 2 Products, and Part 3 Execution.

A bid package typically includes invitation to bid, instructions to bidders, bid form, bid security, general and supplementary conditions, specifications, drawings, and addenda.

Contract types: lump sum for fully defined scope, unit price where quantities are uncertain, cost-plus-fee, and guaranteed maximum price with a shared savings clause.

Submittal review actions are approved, approved as noted, revise and resubmit, and rejected; review does not relieve the contractor of compliance with the contract documents.

Only a change order signed by owner and contractor, or a construction change directive signed by owner and design professional, modifies contract cost or time; an RFI response does not.

Payment applications use AIA G702 with a G703 continuation sheet; retainage commonly runs 5 to 10 percent and final payment follows final completion and lien waivers.

Substantial completion is the point at which the work is usable for its intended purpose; it starts warranty periods, shifts risk and insurance responsibility, and often triggers retainage release.

Concrete flatwork: 3,000 to 4,000 psi at 28 days is typical; use 4 inches for pedestrian paving and 5 to 6 inches for vehicular loads, over a compacted aggregate base.

Control joints are spaced about 2 to 3 times slab thickness in feet (8 to 12 feet for a 4-inch slab); isolation joints separate paving from walls, columns, and other fixed elements.

Subgrade is compacted in 6- to 8-inch lifts to about 95 percent Standard Proctor density, with 4 to 6 inches of base under walks and 6 to 8 inches under drives.

Light-duty asphalt sections use 2 to 3 inches of compacted asphalt over 6 to 8 inches of compacted aggregate base, with a minimum 2 percent surface slope for drainage.

Segmental pavers require 1 to 1.5 inches of bedding sand over 4 to 6 inches of compacted base, plus an edge restraint to prevent lateral creep.

Brick masonry uses 3/8-inch mortar joints; Type N mortar suits general above-grade work and Type S provides higher compressive strength where required.

Alkaline copper quaternary (ACQ) preservative-treated lumber corrodes plain steel, so hot-dip galvanized or stainless steel fasteners and connectors are required.

Retaining walls need a drainage system behind the wall: washed gravel wrapped in filter fabric, a perforated collector pipe, and weep holes to relieve hydrostatic pressure.

Tree protection fencing should enclose at least the dripline, ideally 1 foot of radius per inch of trunk diameter, with no grade change or stockpiling inside the zone.

Slope percent = (rise divided by run) times 100; convert to ratio form as 1:(run divided by rise), so 2 percent equals 1:50.

Minimum grades: 1 percent for paved drainage (2 percent preferred), about 2 percent for turf, and 0.5 to 1 percent for swales; accessible routes cap running slope at 5 percent and cross slope at 2.08 percent.

Contour reading rules: the interval is constant across a drawing, hachures point into depressions, and contour Vs point upstream where they cross a drainageway.

Rational method: Q = CiA, with C near 0.9 for pavement, 0.2 to 0.3 for lawn, and 0.1 to 0.2 for woodland; intensity is read from an IDF curve at the time of concentration.

NRCS TR-55 curve numbers run from about 30 to 98: pavement 98, good-condition lawn about 61, and good woodland about 55; hydrologic soil groups run from A (highest infiltration) to D (lowest).

Conversions: 1 acre = 43,560 square feet; 1 cubic foot per second = 448.8 gallons per minute; 1 inch of rain over 1 acre = 3,630 cubic feet of runoff volume.

Detention volume equals the storm inflow volume minus the allowable release volume integrated over the storm; release rates are often set near 0.1 to 0.2 cfs per acre.

Bioretention design: 6 to 12 inches of ponding depth, 2 to 3 feet of engineered media, an underdrain, complete drawdown in 24 to 48 hours, and a surface area roughly 5 to 10 percent of the contributing impervious area.

Earthwork balance uses the average end area method, V = ((A1 + A2) divided by 2) times L, to compute cut and fill volumes between stations.