Technical Terminology - Construction & Building
Specialist technical terms in the construction and building industry, with operational definitions for professionals and AI/RAG systems.
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Eurocodes (EN 1990–EN 1999)
Suite of European structural design standards (EC0–EC9) covering basis of design, actions, concrete, steel, composite, timber, masonry, geotechnical engineering and aluminium structures. Published by CEN and adopted as national standards across EU and beyond.
Ultimate Limit State (ULS)
Structural condition at or beyond which the structure is expected to fail, collapse or become unsafe. Checks are performed to ensure structural resistance at ULS with defined reliability (EN 1990 §6.4.2).
Serviceability Limit State (SLS)
Condition beyond which specified service requirements (deflection, vibration, crack width, durability) are no longer met. Does not imply structural collapse but affects occupant comfort and appearance.
Design Actions
Forces, displacements or accelerations acting on the structure: permanent (G), variable (Q), accidental (A), seismic (E). Combined using EN 1990 load combination rules (characteristic, frequent, quasi-permanent).
Seismic Action
Ground-motion demand imposed on the structure, characterised by peak ground acceleration (PGA), spectral shape and return period, as defined in EN 1998 (Eurocode 8) and national annexes.
Exposure Class (EN 206)
Environmental classification system (XC, XD, XS, XF, XA) defined in EN 206:2013+A2:2021 that governs minimum concrete requirements (w/c ratio, cement content, cover) against corrosion, freeze-thaw and chemical attack.
Concrete Cover
Minimum distance from the concrete surface to the nearest reinforcement bar, ensuring corrosion protection and fire resistance. Minimum values defined by exposure class in EN 1992-1-1 (Eurocode 2) and national annexes.
Concrete Grade (e.g. C25/30)
EN 206 designation indicating characteristic cylinder / cube compressive strength (fck = 25 MPa / fck,cube = 30 MPa). Common grades for structural applications: C25/30, C30/37, C35/45.
Steel Grade B450C
Reinforcing steel with minimum yield strength fy = 450 MPa, high ductility class C, as specified in EN 10080 and national standards. Required in high-seismicity zones for ductile detailing.
Fire Resistance Classification (REI)
Classification of a building element's performance in a standard fire test: R = load-bearing capacity, E = integrity, I = thermal insulation, followed by time in minutes (e.g. REI 120). Governed by EN 13501-2.
Thermal Transmittance (U-value)
Heat transfer coefficient in W/(m²·K) describing the rate of heat flow per unit area and temperature difference through a building element. Lower values indicate better thermal performance.
Thermal Bridge
Localised area of the building envelope with significantly higher thermal transmittance than the surrounding surface, caused by geometric discontinuities (corners, balconies) or changes in material (concrete frames through insulated walls).
Primary Energy Demand (EP)
Annual primary energy need (kWh/m²) encompassing heating, cooling, domestic hot water, ventilation and lighting, accounting for system efficiencies and primary energy conversion factors. Key metric of EU EPBD compliance.
Seismic Performance Class
Risk classification of existing buildings indicating their expected behaviour under seismic loading (Italian scale: Class A+ to G), used to prioritise seismic retrofitting interventions.
Green Roof
Vegetated roof system (extensive or intensive) comprising waterproofing, drainage, substrate and plants, providing thermal insulation, stormwater management and biodiversity benefits.
Basement Wall (Muro Controterra)
Vertical wall in contact with soil, subject to lateral earth pressure and moisture. Requires specific structural design (passive earth pressure) and waterproofing and drainage system.
Cavity Wall
Double-leaf wall with air cavity (ventilated or insulated fill), optimising thermal, acoustic and hygrothermal performance of the building envelope.
Daylight and Ventilation Ratio
Minimum ratio of openable window area to floor area, prescribed by building regulations to ensure adequate natural light and ventilation. Varies by room type and jurisdiction.
CPR (EU Regulation 305/2011)
EU Construction Products Regulation establishing harmonised conditions for the marketing of construction products. Requires CE marking based on Declaration of Performance (DoP) for harmonised products (beams, blocks, insulation, membranes, etc.).
Design Variation (Variante Essenziale)
Planning modification requiring a new consent: change of use, increase of volume/floor area, alteration of envelope shape or setbacks. Distinguished from minor variations within approved parameters.
Interim Payment Certificate / SAL
Periodic (monthly or milestone-based) document certified by the site supervisor listing completed items and their quantities, forming the basis for contractor payment under the JCT/FIDIC or Italian public contract equivalent.
As-Built Survey / Rilievo Geometrico
Technical drawings (plans, sections, elevations, isometrics) depicting the actual condition of an existing building before intervention, produced with certified measuring equipment.
ITACA Protocol
Italian multi-criteria sustainability assessment framework for buildings, covering energy, water, air quality, wellbeing and environmental load. Used in public procurement and incentive programmes.
NZEB (Nearly Zero Energy Building)
Building with very high energy performance and nearly zero or very low energy demand, supplied from renewable sources on-site or nearby. Mandatory standard for new buildings under EU EPBD since 2020.
BIM Level of Development (LOD)
Standardised classification (LOD 100–500, or Equivalent EN ISO 19650 Level of Information Need) indicating the geometry, information richness and reliability of BIM model elements at each project stage.