Home Inspection Glossary: B-61 Thru B-70 "Blower" ===> "Bolt"
Welcome to The Home Inspection Glossary B-61 — B-70, the latest installment in our ongoing glossary series for home inspectors, and curious homeowners. This edition dives into essential terms ranging from “Blower” and “Blower Door Test” to “Bolt,” providing concise, inspector-focused definitions along with practical notes to improve your inspections and reporting. Whether you’re refining your vocabulary or expanding your technical knowledge, these entries are designed to keep your inspections clear, accurate, and professional.
Blower:
A commonly used term referring to the fan assembly inside HVAC systems that circulates air through ductwork for heating or cooling. The term is also used in the context of a blower door, which is part of a diagnostic test for measuring a building’s air leakage. While “blower” is widely used informally, inspection reports typically refer to more specific components such as the blower motor, blower assembly, or air handler.
Inspector's Note: Inspectors should be familiar with the term “blower” in everyday use but are advised to describe HVAC and air movement systems using precise terms when possible.
Related Terms: HVAC System, Blower Door Test, Air Handler, Furnace
Blower Door Test:
A diagnostic procedure used to measure the airtightness of a building by depressurizing or pressurizing the structure with a calibrated fan temporarily mounted in an exterior doorway. The test reveals how much air is leaking into or out of the building and helps identify specific areas where air sealing improvements may be needed.
Inspector's Note: Blower door testing is performed by trained specialists, including energy auditors, HVAC technicians, and weatherization professionals. While home inspectors do not typically conduct these tests, familiarity with the process and its implications is important—especially in newer or renovated homes where airtight construction is a performance goal. In many jurisdictions, blower door testing is required for code compliance under the International Energy Conservation Code (IECC) or equivalent local standards. The test is often paired with thermal imaging or smoke tools to help locate air leaks during construction or diagnostic evaluations.
Related Terms: Air Sealing, Air Infiltration, Thermal Imaging, Energy Audit, HVAC, Building Envelope, IECC
Blown-In Insulation:
Insulation material installed using mechanical blowing equipment to distribute loose fibers into attic spaces or enclosed wall cavities. Common materials include fiberglass and cellulose. In attic floors, the insulation is typically installed as loose-fill, while wall cavities are usually filled with densely packed cellulose to reduce settling and improve air resistance.
Inspector’s Note: Disturbance or displacement of blown-in insulation—especially from foot traffic or air movement—can reduce its effectiveness. While the installation requires specialized equipment, minor redistribution or repair can often be performed manually using a leaf rake or even by hand. Inspectors should avoid assuming that small repairs require professional intervention.
Related Terms: Cellulose Insulation, Fiberglass Insulation, Batt Insulation, R-Value, Attic Ventilation, Air Sealing
Blown Insulation:
See Blown-In Insulation above.
Blueprints:
A traditional term for detailed architectural or engineering drawings that illustrate the design, dimensions, and layout of a construction project. Although modern plans are typically printed digitally and may not use the original blue-tinted process, the term "blueprints" remains common for referring to construction drawings.
Inspector's Note: Inspectors may reference blueprints when performing phase inspections or evaluating construction progress. However, interpretation of blueprints is generally beyond the scope of a standard home inspection unless specifically agreed upon.
Related Terms: Construction Documents, Specifications, Scope of Work (Construction)
Blue Stain (Wood):
A discoloration of wood caused by fungal growth, resulting in blue, gray, or black staining of the sapwood. Blue stain fungi penetrate the wood's surface but do not significantly weaken its structural strength.
Inspector's Note: Home inspectors may observe blue stain in framing lumber, especially in pine, spruce, or fir species. While it may be unsightly, blue stain does not compromise the load-bearing capacity of the wood. Inspectors should distinguish blue stain from true wood decay, which softens and weakens wood fibers. Blue stain is cosmetic, not structural.
Blue stain causes discoloration but does not weaken the wood structurally.
Board and Batten:
A siding or interior wall system consisting of wide vertical boards with narrower strips (battens) covering the joints between the boards. Board and batten construction provides a distinctive, layered appearance and was historically used for barns and early American homes. Today, it is used in both traditional and modern architectural styles for exterior and interior finishes.
Inspector's Note: Home inspectors should examine board and batten siding for signs of water intrusion at board seams, batten attachment points, and along lower edges near foundations. Proper flashing, caulking, and spacing are critical for durability. In older installations, inspectors should check for signs of board warping, splitting, or gaps that could allow moisture entry.
Boiled Linseed Oil:
Linseed oil that has been chemically treated to accelerate its drying time and improve its handling for use as a wood finish or additive in oil-based paints. Boiled linseed oil penetrates wood surfaces, providing moderate water resistance, enhancing grain appearance, and offering some protection against weathering.
Inspector's Note: Home inspectors may encounter older wood surfaces, such as siding, porch floors, or trim, that were finished with boiled linseed oil. Over time, untreated or poorly maintained linseed oil finishes can become dry, brittle, or darkened, and may require re-coating or full refinishing. Inspectors should observe for signs of cracking, moisture intrusion, or surface degradation on exposed wood finishes.
Boiler:
A heating appliance that heats water or creates steam for distribution through a building’s heating system, typically using radiators, baseboard units, or radiant floor systems. Boilers may be fueled by natural gas, oil, propane, or electricity.
Although the term "boiler" traditionally refers to appliances that create steam, many modern residential boilers heat water without reaching the boiling point.
Inspector's Note: Home inspectors should observe boilers for general operational condition, visible corrosion, leaks, signs of overheating, and proper venting of combustion gases (where applicable). Common defects include rusting, leaking relief valves, aging expansion tanks, or improper flue connections. Inspectors are not required to dismantle boilers but should recognize the type (hot water vs. steam) and report visible defects or safety concerns.
Bolt:
A movable metal bar within a lock mechanism that extends into a strike plate or adjacent surface to secure a door.
Inspector's Note: In residential settings, bolts are part of the locking hardware used to secure doors.
Two primary bolt types that are parts of lock assemblies are:
Latch bolt: A spring-loaded bolt that retracts with the door handle and automatically extends when the door closes.
Deadbolt: A manually operated bolt that provides added security by extending further into the door frame and resisting forced entry.
Inspectors should check that:
—The bolt fully engages the strike plate, the strike plate is securely fastened
—There is no excessive play or misalignment
—Deadbolts, when present, are operable and appropriate for exterior doors
Related Terms: Deadbolt, Strike Plate, Lockset, Entry Door, Security