Glossary

Alluvium · Anti-heave precautions · Bay · Beam and base · Boulder clay (glacial till) · BRE Digest 251 · CCTV drain survey · Chartered engineer (CEng MIEI) · Clay drain · Commencement Notice · Compressible ground · Crack monitor · Damage category · Damage condition rating · Defective concrete blocks · FSPO · Grout injection · Heave · Karst · Landslip · Made ground · Mass concrete underpinning · Mini-pile · PanGeo · Particular risk · Party structure · Peat · Pile cap · Piled raft · PSCS · PSDP · Pyrite heave · Resin or geopolymer injection · Retention (retained amount) · Settlement · Site (ground) investigation · Strip foundation (footing) · Subsidence · Subsidence excess · Underpinning · Works order

Alluvium

Sediment laid down by rivers, and in lakes and estuaries. Often soft and compressible.

Anti-heave precautions

Design measures that stop swelling clay from pushing a new foundation up.

Bay

One short section of underpinning, dug and concreted in a sequence set by the engineer.

Beam and base

Underpinning where a reinforced concrete beam carries the wall to mass concrete bases at chosen points.

Boulder clay (glacial till)

Clay with stones, left by glaciers. Much of Ireland's lowland is on it. TGD A grades it from stiff to loose for foundation design.

BRE Digest 251

BRE's guide to assessing damage in low-rise buildings, with six crack damage categories from 0 to 5.

CCTV drain survey

A camera run through the drains to find cracks, open joints and collapses.

Chartered engineer (CEng MIEI)

The professional title Engineers Ireland awards. Engineers on the register under the 1969 Act can act as assigned certifiers.

Clay drain

An older drain of short clay pipes with unsealed joints. Irish engineers blame leaking clay drains for most subsidence.

Commencement Notice

Notice to the council, 14 to 28 days before work starts, for works the Building Regulations apply to. Not needed for works requiring neither planning permission nor a Fire Safety Certificate.

Compressible ground

Soft ground such as peat, alluvium and estuarine silts and clays that compresses under load, lowering the surface.

Crack monitor

A gauge fixed across a crack to show over months whether it is opening.

Damage category

A crack's grade on the BRE scale: 0 to 2 aesthetic, 3 and 4 serviceability, 5 stability.

Damage condition rating

The rating a pyrite-affected home is certified with. The Pyrite Remediation Scheme required a rating of 2.

Defective concrete blocks

Blocks with too much mica or pyrite that absorb water, lose strength and crumble. Covered by the Defective Concrete Blocks Grant Scheme in some counties.

FSPO

The Financial Services and Pensions Ombudsman: independent and free, for complaints against insurers once the insurer's own process is done.

Grout injection

Pumping liquid concrete (grout) into weak ground under a foundation to restore its strength.

Heave

Upward movement of the ground, or of fill under a floor, as it swells. Pyrite heave is one kind.

Karst

Limestone ground shaped by the rock dissolving. Geological Survey Ireland keeps a database of karst features and says karstified bedrock can cause subsidence.

Landslip

Movement of ground down a slope. Listed with subsidence and heave in Irish home policies.

Made ground

Ground placed by people rather than nature: anything from engineered fill to material with voids or material that can compress, decompose, dissolve or expand.

Mass concrete underpinning

Digging under an existing footing in short bays and filling each with concrete, down to firmer ground.

Mini-pile

A small-diameter pile, normally 150 to 300 mm, carrying load down to stable ground, usually more than 5 m down.

PanGeo

A European project in which Geological Survey Ireland mapped potential and observed ground instability in Co. Dublin and Cork City.

Particular risk

Construction work the HSA treats as higher risk, including deep excavations in poor soil.

Party structure

A wall, floor or other structure dividing two separately owned buildings, or so close to the boundary that work needs access next door. Covered by the party structures chapter of the Land and Conveyancing Law Reform Act 2009, from section 43.

Peat

Partly decayed plant material forming bog. Compressible ground.

Pile cap

A concrete block or beam on top of piles that picks up the wall.

Piled raft

A grid of piles under a reinforced concrete slab over the whole floor, supporting every wall. Internal floors are removed.

PSCS

Project Supervisor Construction Stage: coordinates safety on site. Needed in the same cases as the PSDP.

PSDP

Project Supervisor Design Process: coordinates safety in the design. Needed for projects with a particular risk, more than one contractor or over 30 days.

Pyrite heave

Swelling of hardcore containing reactive pyrite under ground-floor slabs, cracking floors and walls.

Resin or geopolymer injection

Injecting an expanding material through small holes into the ground under a footing.

Retention (retained amount)

Part of an insurance settlement held back until the repair is finished: up to 5% under €40,000, up to 10% at €40,000 or more.

Settlement

Movement of the ground and foundations caused by the weight of the building itself. Often seen early in a building's life. Usually not insured.

Site (ground) investigation

Trial holes and tests to find what the ground is and how deep firm ground lies. TGD A says it's essential for soft or loose subsoils.

Strip foundation (footing)

A continuous strip of concrete under a wall. TGD A sets minimum widths and a minimum thickness of 200 mm for new work.

Subsidence

Downward movement within the ground under a building, independent of the building's own load. Usually an insured event.

Subsidence excess

The part of a subsidence claim you pay yourself, shown on your policy schedule.

Underpinning

Strengthening the foundation of an existing building by making it deeper or wider, so it rests on firmer ground or spreads its load further.

Works order

A District Court order letting a building owner carry out works to a party structure when the neighbour won't agree.