RICS Level 2 Survey in BN45

The geology of BN45 is defined by the transition between the chalk of the South Downs and the clay-rich soils of the Low Weald to the north. The chalk escarpment rises sharply at the southern edge of BN45, and the villages sit on the narrow band of land at its foot where geology changes quickly across a short distance. Understanding this transition matters when buying property here.

The Upper Chalk that forms the Downs is a free-draining, relatively stable geology - it does not shrink and swell like clay, and it does not compact under load in the way that alluvial soils might. However, at the scarp foot, chalk gives way to a mix of Upper Greensand and Gault Clay. The Gault Clay in particular is a high-plasticity material with well-documented shrink-swell behaviour. Properties sitting on or near this geological boundary need careful foundation assessment.

A distinctive feature of chalk escarpment edges is the emergence of springs where groundwater tracking through the chalk meets the impermeable clay below. In BN45 and the surrounding downland villages, these springs create winterbourne streams and boggy ground that can remain wet throughout winter and spring. For properties close to spring lines, ground drainage and rising damp are genuine risks that our surveyors assess during the inspection, including checking sub-floor ventilation, ground levels relative to damp-proof course, and any evidence of ground water ingress at lower floor levels.

Flint is the signature building material of the South Downs villages, and BN45 has a high concentration of flint-built properties. Traditional flint walls are constructed from knapped flint or rounded field flint, bonded with lime mortar. When this combination is intact and well maintained, it forms a robust, breathable wall that has survived centuries. The problems arise when modern intervention has altered the original construction.

The most common issue our inspectors find in BN45 flint properties is inappropriate repointing with hard cement mortar. Lime mortar is soft and permeable, allowing moisture to move through the wall and evaporate harmlessly. Cement mortar is rigid and impermeable - it forces moisture to find alternative escape routes, often into the interior of the wall or behind the face material. Over time this causes frost spalling, loss of face material, and damp penetration into the property interior.

Our surveyors assess flint wall condition carefully, noting the type of mortar in use, the condition of the flint face, and any areas where new cement has been applied over original lime. We use calibrated moisture meters at intervals across all external wall faces to detect elevated moisture levels, and we check both the external and internal wall faces for staining and damp evidence. Where significant repointing with cement is evident, we recommend seeking specialist advice on lime mortar reinstatement before the problem advances further.

• Mortar type: lime (appropriate) vs cement (problematic in solid walls) - checked at all elevations
• Flint face condition: displaced, spalled, or loose flints noted with map reference in report
• Internal wall faces: tide marks, salt efflorescence, and staining checked and moisture-metered
• Window and door reveals: junctions between flint and timber or brick checked for gaps and water entry points
• String courses and copings: condition of decorative brick or stone courses that cap and protect the wall head

Our chartered surveyors carry out a methodical inspection following the RICS Home Survey Standard, covering all main elements from boundary to ridge. In BN45, the inspection places particular emphasis on the elements most likely to affect older rural properties at the foot of the South Downs.

The roof is inspected from ground level using binoculars, looking at tile or slate condition, ridge mortar, lead flashing condition at chimney junctions, and the state of all verge and eaves details. Where roof space access is available, our surveyors inspect the internal structure, noting rafter and purlin condition, any moisture ingress or staining on timbers, and the depth and coverage of insulation. For older properties with complex roof shapes - catslide roofs, cross-ridges, and hipped sections - each junction is assessed separately.

Ground floor inspection in BN45 properties pays particular attention to sub-floor conditions, especially where the property sits close to the chalk escarpment foot. We check the condition of air bricks, looking for blockages that prevent sub-floor ventilation, and we probe timber floor joists where accessible to detect rot or insect attack. In properties where a concrete ground floor has replaced original suspended timber, we check for any evidence of rising moisture bridging through the floor slab.