Generally, I am looking for visible or otherwise observable deficiencies of the following systems and components:

Grounds and Appurtenances --- Grading and surface drainage - water should drain away from the structure.  Ground cover and vegetation should be appropriate to facilitate drainage away from the house while being far enough away form the structure to not adversely affect the foundation/slab.  Fences (around pools, hot tubs or spas) shall be sturdy, and not allow entry by unauthorized persons.  Outdoor lighting should be installed to local standards.  Paved areas (driveways, walkways, and patios) should be functional and well maintained, and should not have tripping hazards. Paved areas should also aid in draining water away from the structure.  Exterior steps (not attached to house) should have correctly sized risers and treads and be equipped with handrails.  Retaining walls and outbuildings should be correctly erected and safe.  Electrical service lines, if overhead, should be far enough from the ground to prevent inadvertent hazard.  Main water service should be accessible and the cut-off valve and meter should be accessible.  Cleanout for waste disposal system (septic or public) should be accessible.

Building Exterior --- (items that attach to the house)  I inspect exterior foundation walls for exposed footings, cracks, leaning, vertical movement, bulges and WDO (wood destroying organisms).  I check landings, porches and decks for proper distance from thresholds, adequate attachment to the house, and adequate guardrail systems.  I check steps at porches and landings for consistent and correctly sized risers and treads, as well as handrails.  Porches support porch roofs, and I inspect for adequate roof support.  I inspect siding materials (wood, particleboard, OSB, fiber-cement board, masonry, stone, aluminum, vinyl, and brick) for deficiencies particular to the material.  The Electrical service and meter are usually attached to the exterior of the house. I check the service entrance (the main electrical panel) for proper installation and a service disconnect.  This is where the neutral -ground bond should be located. If natural gas is supplied, the gas mater is usually attached to the house exterior.  I look at the A/C condensing unit, report on its condition, age, BTU rating, and whether it is sized to properly cool your house.  I check that the required disconnect is easily reachable and not blocked by the A/C unit.  I check for insulation on the refrigerant lines, and that all A/C penetrations through the exterior of the house are properly sealed.  I look at each window and frame and check for broken/cracked glazing, rotting in sills and frames, and proper flashing.  Exterior doors and doorframes are also given a close look.  I look at window screening, cornice work, and gutters and downspouts. I check the condition of any paint on the exterior.  I look at fireplace chimneys to ensure their height is acceptable, a cricket is installed (if needed), and flue caps are installed.

Roofing and Other Components --- Depending on roof pitch, material and the weather, I will walk the roof during the inspection.  If I do not walk the roof, I will inspect it with binoculars from a ladder and from the ground.  Most deficiencies are "seeable" with either method.  It is easier and faster to walk the roof, though.  I look for too low of a pitch, loose or missing shingles, hail damage, holes from toe boards, blistering, cupping, and general wear for asphalt/fiberglass composition shingle roofs.  With wood shingle or shake roofs, I check pitch, loose or missing shakes, rot, splitting, cupping or curling, moss or mildew.  Each type of roofing material (shingles, shakes, slate, tile, cement, etc.) has its own particular failure modes.  I modify my inspection routine for the type(s) of roofing involved.  During the roofing inspection, I also check all visible flashing, skylights, and other roof penetrations for adequate installation and leaks.  Most roof repairs are at valleys, roof/sidewall junctions, dormers, and chimneys. I try to check these areas closely.

Garage/Carport --- The garage floor needs to be sloped toward the garage doors to aid drainage away from the structure.  Gas fueled appliances (water heater, forced air furnace, etc.) need to be raised so that the burner or spark line is at least 18 inches from the floor.  Likewise, all electrical outlets must be at least 18 inches above the floor of the garage.  If the water heater and furnace units are in the garage space, they must be protected from automobiles by bollards or other means to separate them from the automobile parking area.  The dwelling area must be protected from fire by fire-retardant gypsum and fire-rated doors or a sprinkler system in the garage.  Automatic garage door openers should work properly and the safety reversal feature must work correctly.  All outlets in the garage (except for the permanent garage door opener outlets) must be GFCI outlets.

Interior --- I operate every operable window and door in the interior of the house.  I check each accessible electrical outlet in the house with either a multimeter or a circuit tester.  I test each GFCI outlet in the house (these are located in the kitchen, bathrooms, garage, and outside).  I check for appropriate levelness of floors.

In the kitchen, I run the dishwasher, stove / range, waste disposal, and vent fan / hood. I inspect all cabinetry and under-sink and under-counter areas.

In the laundry room, I look at washer/dryer electrical and plumbing hookups, washer drain lines, and dryer vent ductwork.

I check each fireplace for safety, an operational damper, and adequate firebox and hearth dimensions.

Stairways in the house must meet minimum standards of consistency, size of risers and treads, overhang of treads, and strength/placement of guard/handrails. The stairs must be lighted with a lightswitch available at the top and bottom of the stairs. I check for these conditions and report on deficiencies.

Bathrooms must have adequate water supply to run three fixtures at once. The lavatories and tubs must be able to drain through overflow drains. Electrical outlets within 6 feet of any water source must be GFCI outlets.

Bedrooms must have adequate secondary means of egress (a window or door that allows emergency exit or firefighter access). The open portion of the window must be wide enough and tall enough for a firefighter with equipment to gain access to the house and its occupants. The opening must be at least 5 sq. ft. if the window is at grade level and 5.7 sq. ft. if it is a 2^nd floor window.

Attic --- I inspect and report on the type of attic access, whether there is heating and ventilation equipment installed there, plumbing fixtures and vent stacks, etc. I look at the type and quantity of insulation installed. I report on attic ventilation (soffit vent, ridge vents, etc.) and its adequacy. I inspect attic framing, report whether it is conventional or engineered trusswork, and opine on the quality of construction and materials. I look for leaks (especially in areas singled out during the roof inspection) and evidence of recent or chronic leaking.

Slab / Basement /Crawlspace --- If I'm inspecting a slab, there's not much to see. Most of the thing is hidden. If I can see it, I'll report on spalling, cracks, settlement, or evidence of WDO.

Plumbing --- I look at all visible water piping, and note the material(s). I locate and verify the main shut-off and pressure reducer, and if possible, check the water pressure. I check for an electrical bonding strap. I look for things in contact with water piping that should not be there (such as electrical wiring). Of course, I inspect for leaks, and will let you know if I suspect any lead in the system.

I inspect the visible waste piping to determine the proper materials and installation. I check that the fall of waste piping is adequate for drainage. I check for adequate strapping/hanging of the drain/waste piping. I check to make sure the system vents through the roof.

I determine the age and condition of the water heater. I look for adequate ventilation if it is a gas water heater. I determine whether the water heater is sized properly for the house. I check the electrical power connections at the water heater. I examine and test the TPR (Temperature and Pressure Relief) valve and piping.

HVAC --- I look at the age and capacity of the air handler/furnace unit(s) to determine if it is sized for the house. I check the condition of the thermostat(s). I inspect visible and accessible ductwork for integrity and common sense installation and placement in the house. I remove and replace filter(s) to check for cleanness and ease of replacement. I operate heating equipment when feasible. Primary and secondary condensate drains lines are visually inspected.

Operation of AC --- Weather permitting, I operate the A/C equipment using the normal control devices.  I inspect the unit to determine general condition and age.

Electrical Panels --- I always open (weather permitting) and inspect each electrical panel in the structure. The service entrance, which contains the main circuit breaker or switch for the property, should have adequately sized conductors and the neutral-ground bond. In all other electrical panels, neutrals (grounded conductors) should be isolated from ground. Most electrical panels are rife with homeowner induced deficiencies, such as doubled up neutrals or double conductors connected to circuit breakers, doorbell transformers installed inside the panel, undersized conductors, etc.

These are a few of the things I look at during a typical inspection.