MI General Contractor key terms

The weight a building must support from occupants, furniture, and movable equipment. Building codes set minimum live loads by room use, such as 40 psf for residential sleeping areas and more for decks and stairs.

The permanent weight of the structure itself plus permanently attached materials such as roofing, insulation, drywall, and flooring. It stays constant over the life of the building and is added to live load in structural design.

A number stamped on engineered wood panels showing the maximum allowable roof and floor joist spacing, such as 24/16. The first number applies to roof supports and the second to floor supports.

The maximum permitted sag of a beam, joist, or floor under load, usually expressed as a fraction of the span such as L/360. Exceeding it causes cracked finishes and bouncy floors even if the member does not break.

The horizontal framing member bolted to a house wall that supports the inner end of deck joists. Correct flashing and lag or through-bolt attachment are critical because ledger failures cause many deck collapses.

A galvanized steel bracket that connects a joist end to a ledger, beam, or header and carries the joist load into that member. Hangers must be sized for the joist, filled with the specified nails, and protected from moisture.

The outer joist running perpendicular to and enclosing the ends of floor joists, tying the floor frame together. It transfers loads to the foundation and provides a nailing edge for sheathing and exterior finishes.

The continuous framing member along the perimeter of a floor system, also called a rim board, that closes the joist ends and caps the foundation sill. It must be sized to match the floor sheathing and often carries vertical loads from walls above.

The pressure-treated wood member anchored to the top of the foundation wall that the floor frame and wall framing attach to. It must be rot-resistant and secured with anchor bolts or approved anchors at required spacing.

A threaded steel bolt embedded in concrete foundation walls or slabs to tie the wood sill plate to the foundation. Codes specify diameter, embedment depth, and spacing to resist uplift and lateral loads.

The widened concrete base at the bottom of a foundation wall or column that spreads building loads over a larger soil area. Footings must bear on undisturbed soil below frost depth and meet minimum width and thickness requirements.

The depth to which soil freezes in winter, which sets how deep footings must be in a given area. Footings placed above this depth risk heaving and cracking unless an engineered frost-protected shallow foundation is used.

A foundation design that places footings above frost depth but insulates the soil around the perimeter to prevent freezing under the building. It requires code-specified insulation placement and drainage detailing and is common in cold Michigan climates.

A material that blocks water vapor from moving through an assembly, such as the plastic sheet under a concrete slab. Placement depends on climate and assembly type, and a misplaced barrier can trap moisture and cause rot.

A material or coating that slows water vapor diffusion through walls, ceilings, or floors, rated by its permeability. In cold climates it goes on the warm side of insulation, while warmer climates often require it omitted or placed differently.

The continuous system of materials that stops uncontrolled air movement through the building envelope. Air leaks carry far more moisture and heat than diffusion, so sealing penetrations and joints matters more than adding insulation alone.

A sheet weather-resistive barrier installed over wall sheathing under siding to shed bulk water while allowing vapor to escape. Horizontal laps must shed water downward, and all penetrations must be flashed and taped.

Sheet metal or membrane installed to direct water away from joints and penetrations such as roofs, walls, windows, and decks. Flashing must lap shingle-fashion, be integrated with the weather barrier, and be detailed at every transition.

A ridge of ice at the roof edge formed when snowmelt refreezes, forcing water backup under shingles and into the building. Prevention relies on attic air sealing, insulation, ventilation, and a properly installed ice barrier underlayment.

A water-resistant layer between roof sheathing and shingles that provides a secondary barrier against wind-driven rain and ice backup. Some codes require a self-adhering membrane along eaves in cold climates.

A metal flashing along roof edges that sheds water clear of the fascia and siding and protects sheathing edges. It must be installed in the correct lapping order with underlayment and shingles to work properly.

An operable window or door in a sleeping room or basement that provides an emergency escape path meeting minimum opening area, width, height, and sill height rules. It must open without keys or special tools.

A protective rail installed along open edges of decks, stairs, and balconies to prevent falls. Codes specify minimum height, maximum baluster spacing so a child cannot pass through, and load resistance requirements.

A graspable rail along a stairway or ramp that people hold for support. It has its own height range, profile, and continuity rules that differ from guardrail requirements, and both may be required on the same stair.

The vertical height of a single step, measured from the top of one tread to the top of the next. All risers in a flight must be equal within a small tolerance, and the code sets maximum height and minimum tread depth.

A device that detects smoke and sounds an alarm, required in sleeping rooms and on each story of a dwelling. Power source, interconnection, and placement rules depend on when the home was built and local amendments.

A detector that warns of dangerous carbon monoxide from fuel-burning appliances or attached garages. Code requires them near sleeping areas in homes with fuel-fired equipment or attached garages.

A diagnostic test that depressurizes a house with a calibrated fan to measure air leakage and locate leaks. Some energy codes require a maximum leakage rate verified by this test before occupancy.

A metal shield placed between the foundation and wood framing to block termites from entering the structure. Michigan has limited termite pressure, but local codes and lender requirements may still call for it.

A legal claim against property securing payment for labor or materials supplied to improve it. In Michigan, contractors and suppliers must follow statutory notice and filing deadlines to preserve lien rights.

A written document in which a contractor or supplier gives up the right to file a lien, either for progress payments or final payment. Owners and lenders often require waivers before releasing funds.

A recorded document that gives public notice that construction is starting on a property and identifies the parties. It affects lien priority and notice obligations for subcontractors and suppliers under Michigan law.

A written amendment signed by the owner and contractor that modifies the scope, price, or schedule of a construction contract. It protects both parties by documenting agreed changes before work proceeds.

A percentage of each progress payment withheld by the owner until the project is substantially complete. It provides leverage to ensure completion and correction of defects and is limited by state law.

A written list of incomplete or defective items identified near the end of a project that the contractor must correct before final payment. It is typically tied to substantial completion and retainage release.

The longest sequence of dependent tasks in a project schedule that determines the shortest possible completion time. Any delay on the critical path delays the whole project, so it receives the most schedule attention.

The period between ordering a material or scheduling a trade and its arrival or start on site. Long lead times for windows, trusses, or cabinets often drive the schedule and must be ordered early.

The ratio relating a distance on a drawing to the real distance it represents, such as one quarter inch equals one foot. Reading scale correctly is essential for takeoffs and for verifying dimensions on plans.

The process of measuring and listing quantities of materials and labor from construction drawings for estimating. An accurate takeoff with waste factors and unit costs forms the base of a competitive bid.

A worker designated by the employer who can identify hazards and has authority to take corrective action, required for tasks such as excavations and scaffolding. The role is defined by training and experience, not job title.

Sloping, benching, shoring, or shielding used to prevent cave-ins in trenches and excavations. A competent person must inspect it daily, and protective systems are required once depth reaches code thresholds.

Systems and practices that prevent workers from falling from heights, such as guardrails, personal fall arrest, and safe ladder use. Trigger heights and required methods are set by OSHA construction standards.

Work methods required when disturbing paint in pre-1978 housing, including containment, dust control, and cleaning verification. Firms must be certified and workers trained under EPA renovation rules before starting such work.

The regulated removal and disposal of asbestos-containing materials by trained and licensed workers using containment and air monitoring. Disturbing asbestos without controls releases fibers that cause serious lung disease.

Gear such as hard hats, safety glasses, gloves, and respirators worn to reduce exposure to jobsite hazards. Employers must provide required equipment, train workers on its use, and enforce its use on site.