Building & Renovation Glossary

Home Renovation Glossary (Ireland): 100 Building & Renovation Terms Explained

This glossary explains common construction and renovation terms used in Ireland — in plain English.
It’s designed to help homeowners understand quotes, plans, BER upgrades, and what to expect on site.

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Home Renovations · Home Extensions · Kitchen Renovations · Attic Conversions

A

Airtightness

How well a home prevents unwanted air leakage through gaps and junctions. Better airtightness can improve comfort and reduce heat loss, but it must be balanced with proper ventilation (especially important in upgrades and attic conversions).

Air-to-Water Heat Pump

A heating system that uses outside air to heat water for radiators/underfloor heating. Often considered during BER upgrades and larger refurbishments.

Assigned Certifier

A role used on certain projects where compliance documentation and inspections are coordinated (commonly discussed alongside BCAR and building control processes).

Architectural Drawings

Measured and technical drawings showing layouts, dimensions, and notes used for planning, tendering, and construction.

B

Back to Brick

Stripping a room/building back to the original blockwork/brickwork by removing plaster, fixtures, and finishes before rebuilding.

BCAR (Building Control Amendment Regulations)

A compliance framework that may apply to certain works. It involves specific documentation and sign-off processes through the Building Control system.

BER (Building Energy Rating)

A rating of a home’s energy performance (typically A–G). Renovations that improve insulation, heating controls, windows, and airtightness can improve BER.

Blockwork

Walls built using concrete blocks, widely used in Irish homes for structural and internal walls.

C

Cavity Wall

A wall made of two layers (inner and outer leaf) with a cavity between. The cavity may be insulated depending on age and construction.

Certificate of Compliance on Completion

Compliance documentation associated with certain regulated projects, confirming building works meet required standards at completion.

Commencement Notice

A legal notice submitted before starting certain building works, typically through the Building Control Management System (BCMS).

Cold Bridge (Thermal Bridge)

Areas where insulation is interrupted and heat escapes more easily, often around windows, corners, or structural junctions.

D

DAC (Disability Access Certificate)

A certificate relating to accessibility compliance. More common in non-domestic or multi-unit developments, but still a term homeowners may hear.

DPC (Damp Proof Course)

A barrier within a wall designed to stop moisture rising from the ground into the building fabric.

DEAP

Dwelling Energy Assessment Procedure — the calculation method used to produce a BER rating in Ireland.

Drylining

Fixing plasterboard to walls/ceilings (often on battens or adhesive dabs) rather than wet plastering directly onto blockwork.

E

Eaves

The lower edge of the roof that overhangs the wall. Eaves detailing matters for ventilation and insulation continuity.

Energy Upgrade (Retrofit)

Works intended to improve energy efficiency and comfort (insulation, airtightness, heating systems, controls). Often paired with a full refurbishment.

Engineered Timber

Timber products designed for strength and stability (e.g., LVL, glulam, I-joists) used in floors, roofs and structural openings.

Exempted Development

Work that may not require planning permission if it falls within strict limits and conditions (size, location, boundary rules, etc.). Common question for home extensions.

F

Fire Collar

A fire-stopping component used around plastic pipes that pass through fire-rated walls/floors, helping prevent fire spread.

Fire Safety Certificate

A compliance approval relating to fire safety design. More common in non-domestic and certain larger developments, but can come up depending on project type.

First Fix

The stage where hidden works go in before plastering: wiring routes, plumbing pipework, framing, and structural elements. Typical in extensions and attic conversions.

Footings

Concrete poured into excavations to spread the load from walls and support foundations.

G

Gable

The triangular upper part of a wall at the end of a pitched roof.

Grants (SEAI)

Grant supports available for eligible energy upgrades in Ireland (subject to the current SEAI schemes and requirements).

Green Mortgage

A mortgage product some lenders offer for energy efficient homes (often linked to BER rating).

Groundworks

Site works before building starts: excavation, drainage, foundations, services, and preparation.

H

Heat Loss Survey

An assessment (often used for heat pumps) to calculate how much heat a home needs, influencing radiator sizing and system design.

Heating Zones

Dividing your heating system into areas that can be controlled separately (e.g., upstairs/downstairs), improving comfort and efficiency.

Hot Press

An Irish term for an airing cupboard, usually where the hot water cylinder and pipework are located.

MVHR (Heat Recovery Ventilation)

Mechanical Ventilation with Heat Recovery — a system that extracts stale air and brings in fresh air while retaining heat. Often paired with good airtightness.

I

Insulation

Materials added to reduce heat loss through walls, roofs, and floors (e.g., mineral wool, PIR boards). Common in refurbishments and attic upgrades.

Internal Wall Insulation

Insulation added to the inside face of external walls (often with drylining). Used where external insulation isn’t suitable.

I-Joists

Engineered timber joists shaped like an “I”, used for floors/roofs with long spans and stable performance.

Immersion Heater

An electric element inside a hot water cylinder that heats water. Common backup or supplemental hot water method in Irish homes.

J

Joists

Structural beams supporting floors or ceilings. Often upgraded or doubled during attic conversions.

Junction Detailing

How materials meet at corners, windows, and connections. Good detailing reduces drafts, thermal bridges, and moisture risk.

Juliet Balcony

A balcony-style guard rail placed outside full-height doors, common in attic conversions and rear extensions.

Justification Report

A planning-related document sometimes required to explain why a design approach is appropriate for the site and context.

K

Kitchen Work Triangle

A classic kitchen design principle referencing the relationship between sink, hob, and fridge for efficient movement. Useful in kitchen renovations.

Kiln-Dried Timber

Timber dried in a controlled process to reduce moisture and improve stability, helping prevent warping.

Kerb Drainage

Drainage solutions around driveways/patios that help manage surface water, reducing flooding risk.

Keyed Plaster

A roughened surface that helps plaster bond properly to the background surface.

L

Life Cycle / Lifespan (Materials)

How long a material or component is expected to last under normal conditions (important for windows, roofs, boilers, membranes).

Lintel

A horizontal support above windows/doors that carries the weight of masonry above.

Load-Bearing Wall

A wall supporting structural loads (floors/roof). Alterations usually require engineering and often a steel beam.

LVL (Laminated Veneer Lumber)

An engineered timber beam product used for long spans and structural support.

M

Membrane (Vapour / Radon / Damp)

Sheet material used to manage moisture, damp or gases (vapour barriers, radon barriers, DPM). Detailing is critical for performance.

Mortar

The bonding material used between bricks/blocks. Mix type matters for strength and breathability.

MVHR

See MVHR (Heat Recovery Ventilation). A ventilation system that improves air quality while retaining heat.

Mould Risk

Risk of mould growth due to condensation and damp. Often improved by ventilation, better insulation, and reducing thermal bridges.

N

NEAP

Non-Domestic Energy Assessment Procedure (for commercial buildings). Mentioned when a contractor does both domestic and commercial work.

Natural Ventilation

Ventilation achieved via vents, trickle vents, windows, and passive airflow (as opposed to mechanical systems).

Noggins

Short pieces of timber between studs/joists to stiffen the frame and provide fixing points.

Nib Wall

A short return wall (often near a doorway or opening) that can provide structure or a clean finish to a new opening.

O

Open-Plan Layout

Removing or reducing internal walls to create a larger combined space (often kitchen/dining/living). Common in home renovations and kitchen projects.

Oversite Membrane (DPM)

A membrane installed over the ground beneath a floor slab to reduce moisture rising into the building.

OSB (Oriented Strand Board)

A timber sheet material commonly used for roof decking, flooring, and structural sheathing.

Outfall

The point where drainage discharges to a main sewer, soakaway, or other approved outlet.

P

Part L

Part L of Irish Building Regulations covers energy performance requirements (insulation, heating efficiency, controls, etc.). Relevant for extensions and major upgrades.

Part B (Fire Safety)

A section of the Building Regulations relating to fire safety, including escape routes, fire-rated construction, and alarms.

Planning Permission

Approval from your local authority required for certain works. Some projects may qualify as exempted development.

Practical Completion

A stage where the home is usable and essentially complete, with only minor snagging items remaining.

Q

Quality Control (QC)

Checks carried out to ensure workmanship and materials meet the expected standard (often includes photo records and inspection sign-offs).

Quotation

A priced offer for work based on a defined scope. Always check what’s included/excluded, and whether VAT applies.

Quantity Surveyor (QS)

A professional who helps estimate costs, manage budgets, and assess variations — more common on larger renovations and extensions.

Quiet-Close Hinges

Soft-close cabinet hinges commonly included in modern kitchens.

R

Radon Barrier

A membrane installed to reduce radon gas entering the property from the ground. Often discussed in groundworks for extensions.

Rafter

A roof structural member supporting the roof covering. In attic conversions, rafter depth impacts insulation options.

RSJ (Rolled Steel Joist)

A steel beam used to support loads when opening up spaces or removing structural walls.

Retention Permission

Planning permission applied for after unauthorised work has taken place (not guaranteed).

S

Screed

A levelling layer applied over a concrete slab to create a smooth, level base for flooring. Often used with underfloor heating.

Second Fix

The stage where visible fittings are installed: sockets, switches, sanitary ware, doors, final carpentry, etc.

Section 5 Declaration

A request to the local authority to confirm whether planned works are exempt or need planning permission.

Snag List

A list of small defects or unfinished items identified near project completion that need to be corrected.

T

Thermal Bridging

Heat loss at junctions where insulation is interrupted, which can create cold spots and condensation risk.

Trickle Vents

Small ventilation slots (often in windows) that provide background airflow to reduce condensation risk.

Tanking (Bathroom Waterproofing)

A waterproofing system used behind tiles in wet areas (showers, wet rooms) to prevent water damage.

Timber Frame

A construction method using a timber structural frame. Used in some extensions and modern builds.

U

U-Value

A measure of heat loss through a building element (wall, roof, window). Lower U-values mean better insulation performance.

Underfloor Heating

A heating system that warms a room from the floor up, often used in extensions and modern refurbishments.

Upstands

Raised edges on waterproof membranes (often on balconies/flat roofs) to prevent water ingress at junctions.

Utility Room

A practical room for laundry, storage, and appliances — often added in extensions.

V

Vapour Barrier

A membrane used to reduce moisture movement through walls/roofs, helping protect insulation and reduce condensation risk.

Variations

Changes to the original scope after work begins. Variations should be agreed in writing with cost/time impacts.

Ventilation

Fresh air supply and moisture removal. Critical in airtight homes to reduce condensation and improve air quality.

VOCs (Volatile Organic Compounds)

Chemicals released from some paints/finishes. Low-VOC products can improve indoor air quality during renovations.

W

Warm Roof

A roof insulation approach where insulation is placed above the structural deck, helping reduce condensation risk and improve thermal performance.

Wet Room

A fully tanked, waterproof bathroom space with level-access shower and floor drainage.

WHB (Wash Hand Basin)

A common abbreviation used on plumbing drawings and bathroom specs for wash-hand basin.

Wraparound Extension

A combined side and rear extension, common in Irish semi-detached homes, used to create larger open-plan spaces.

X

XPS Insulation

Extruded polystyrene insulation board, often used in floors and areas requiring high compressive strength.

Xylem (Timber Term)

A biological timber term sometimes referenced in material discussions; not commonly used on site, but appears in technical descriptions.

X-Bracing (Cross Bracing)

Diagonal bracing used to stiffen a frame and resist racking forces (wind/load).

X-Actuated Fixings

Powder-actuated fixings used to fasten materials to concrete/steel quickly (requires trained use).

Y

Yield Strength

A materials term describing the stress level where a material begins to deform permanently (often referenced in steel specs).

Yellowing (Paint/Sealant)

Discolouration that can happen to some paints or sealants over time, especially in low light or around heat sources.

Yard Drain

A drainage point in external paved areas that collects surface water and connects to drainage runs.

Y-Piece (Plumbing)

A plumbing fitting that joins two pipe runs into one in a smoother flow than a sharp tee.

Z

Zoning (Heating)

Splitting the home into separate heating zones so different areas can be controlled independently.

Z-Brackets

Fixing brackets used in cladding, insulation systems, or mounting details where a “Z” profile is suitable.

Zero-Threshold (Level Access)

A flush transition between surfaces (common in wet rooms, patio doors, and accessible design).

Zinc Flashing

Flashing material used at roof junctions to shed water and prevent leaks.

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