HomesAndHedge glossary

Home and garden glossary

This glossary explains the everyday terms behind home and garden problems in plain English, grouped by damp and mould, invasive plants, pests, wildlife and the law, drainage, and home maintenance. Each entry gives a definition you can act on: the difference between rising damp and condensation, why Japanese knotweed spreads from its rhizome, what a soakaway does, and what positive input ventilation is for. Definitions follow named UK sources such as the Property Care Association, the RHS, the NHS and gov.uk, so you can understand a survey or a quote and know when a job needs a qualified professional.

Damp, mould and structural

Rising damp: Ground moisture drawn up through masonry by capillary action, typically reaching no higher than about a metre and leaving a tide mark and salt deposits. It is far less common than condensation, and is often misdiagnosed.
Penetrating damp: Water passing horizontally through a wall or roof from an outside defect such as failed pointing, a cracked render or a blocked gutter. It usually appears as a localised damp patch that worsens after rain.
Condensation: Moisture from warm indoor air settling on cold surfaces when they fall below the dew point. It is the most common cause of household damp and the usual trigger for black mould in corners, on cold walls and around windows.
Dew point: The temperature at which air becomes saturated and water vapour turns to liquid. When a wall or window is colder than the room air's dew point, condensation forms on it.
Relative humidity: How much moisture the air is holding compared with the most it could hold at that temperature, shown as a percentage. Persistently high indoor humidity feeds condensation and mould.
Damp-proof course (DPC): A barrier built into a wall near ground level to stop rising damp. It can be a physical layer, such as engineering brick or plastic, or a water-repellent cream injected into older walls.
Efflorescence: The white, powdery salt deposit left on brick or plaster as water evaporates out of it. It signals that moisture has been moving through the material.
Hygroscopic salts: Salts left in masonry or plaster by past damp that then attract moisture from the air, so an area can stay damp even after the original source is fixed. Contaminated plaster often has to be replaced.
Black mould: Surface mould that grows on cold, condensation-prone areas. Beyond the staining, the NHS links damp and mould to coughs, wheezing and worsened asthma, so it is treated as a health issue, not just a cosmetic one.
Tanking: Applying a waterproof barrier to walls and floors, most often in cellars, basements and below-ground rooms, so water in the surrounding ground cannot pass through into the space.

Invasive plants

Japanese knotweed: A fast-growing invasive plant with bamboo-like stems and heart-shaped leaves that can regrow from a fragment of root. It is not illegal to have on your land, but under law you must not allow it to spread into the wild or onto neighbouring property.
Rhizome: The underground stem that stores energy and sends up new shoots. Knotweed spreads through its rhizome network, which is why cut stems and disturbed soil can start fresh growth.
Encroachment: Invasive plant growth crossing a boundary from one property onto neighbouring land, which can give rise to a private nuisance claim if it causes damage or loss of use.
Schedule 9: The list in the Wildlife and Countryside Act 1981 covering plants, including Japanese knotweed, that it is an offence to plant or otherwise cause to grow in the wild.
Management plan: A documented treatment and monitoring programme for an invasive plant, often required by mortgage lenders and usually backed by an insurance-backed guarantee from a specialist contractor.
Stand: An established, self-supporting patch of an invasive plant such as knotweed. The size and age of a stand affect how long treatment takes.

Pests

Infestation: An established pest population that is living and breeding on the premises, as opposed to a one-off sighting of an animal passing through.
Harbourage: The sheltered places where pests nest, rest and hide, such as wall cavities, clutter and undisturbed voids. Removing harbourage is central to lasting control.
Proofing: Sealing the gaps, holes and entry points that let pests in, for example wire mesh over airbricks or bristle strips under doors. It is what stops a treated problem coming back.
Bait station: A tamper-resistant box that holds rodenticide or monitoring bait so it is accessible to rodents but not to children, pets or wildlife.
Rodenticide: A poison used to control rats and mice. Its sale and use are governed by a stewardship regime, and professionals follow strict rules to limit risk to non-target animals.

Wildlife and the law

Protected species: Animals, such as all bats and wild birds, that it is a criminal offence to kill, injure or deliberately disturb under the Wildlife and Countryside Act 1981. Work that could affect them may need a licence.
Exclusion: Humanely keeping or removing an animal without harming it, for example fitting a one-way door so an animal can leave a roof space but not return, then sealing the gap.
Nesting season: The period, broadly spring to late summer, when birds are actively nesting. Disturbing or destroying an active nest is an offence, so hedge cutting and roof work are planned around it.

Drainage and outside

Gully: The fitting at the base of a downpipe or set into the ground that collects surface water and carries it into the drain, usually with a trap to block smells.
Soakaway: An underground pit or crate system, filled with rubble or plastic cells, that holds surface water and lets it drain slowly into the surrounding ground rather than running off.
French drain: A gravel-filled trench, usually with a perforated pipe along the bottom, that intercepts and redirects groundwater away from a building or a waterlogged area.
Inspection chamber / manhole: An access point into the underground drainage run, covered by a removable lid, used to check for and clear blockages.
Combined vs surface-water drain: A combined drain carries both foul waste and rainwater in one pipe; a surface-water drain takes rainwater only, often to a soakaway or watercourse. Connecting the wrong one can cause pollution or flooding.

Home maintenance

Pointing / repointing: The mortar joints between bricks or stones. Repointing means raking out failed mortar and renewing it, which keeps water out and is a common fix for penetrating damp.
Airbrick: A perforated brick set into an outside wall to ventilate a room or the void beneath a suspended floor. Blocked airbricks are a frequent, avoidable cause of subfloor damp.
Positive input ventilation (PIV): A loft or wall-mounted unit that gently pushes filtered fresh air into the home, lowering indoor humidity to reduce condensation and mould.
Subfloor void: The ventilated air gap beneath a suspended timber ground floor. It needs clear airbricks and dry conditions to stop timber decay such as wet or dry rot.

Want the longer version? Read our in-depth guides, or start with the damp and mould, invasive plants and wildlife law hubs.

Oliver Mackman

Editor, HomesAndHedge

Oliver Mackman is the editor of HomesAndHedge and is accountable for its editorial standards and sourcing. He ensures every claim is backed by a named source such as the Property Care Association, the RHS, the NHS or gov.uk, and that the site is clear about when a job needs a qualified professional.

Last reviewed: 8 July 2026