Common Defects in House Surveys

Useful information for buyers

It is unusual to find a property which is free from defects but our home surveys will give you the knowledge you need to decide whether or not to proceed with your purchase. Many of the defects we find can be easily remedied providing you are prepared to accept the cost and inconvenience of the works. Sometimes the vendor may agree to carry out remedial works prior to purchase or the purchase price may be renegotiated to reflect the cost of carrying out unexpected works. In a small number of cases, it may be best to walk away from the purchase altogether.

Everyone has different expectations and, to avoid unnecessary time and expense, it is important that you know how much work you are prepared to carry out. In the majority of cases, older properties will require more extensive remedial works, and therefore expenditure, than newer properties. If funds are limited or you don’t want the inconvenience of works, it may be better to buy something more modern. If you’re not sure what type of property would suit you, our surveyors can help you decide.

Our gallery of common defects provides information on the types of issue we regularly encounter in our surveys.

Dry Rot

Skirting board affected by dry rot1

Dry rot is a fungus that destroys cellulose in timber, eventually reducing it to a dry and crumbly consistency. Warm, humid and unventilated spaces provide the conditions dry rot requires to thrive. It spreads rapidly through a building, behind plaster and through walls into neighbouring properties. Left unchecked dry rot compromises the structural integrity of the building and could lead to its collapse.

  • 1 | Skirting board affected by dry rot

Wet Rot

Wet rot caused by leaking pipework1
Rising dampness causing wet rot to skirting board2

Wet rot is usually caused by a structural defect which allows water to collect on timber, for example, through penetrating or rising dampness, condensation or faulty plumbing. Such defects may include defective guttering or roof tiles, cracked walls, defective pointing and issues with the damp proof course. Wet rot can affect the structural integrity of timber and the affected element may require to be replaced.

  • 1 | Wet rot caused by leaking pipework
  • 2 | Rising dampness causing wet rot to skirting board


Woodworm infestation1

Woodworm infestation can be identified by small holes on the surface of timbers. Woodworm infestation is reasonably common, particularly in older properties, and if often introduced into properties through old furniture which is already affected.  Provided it is treated before the infestation worsens, woodworm is not a cause for undue concern. However, heavily infested timbers will become sponge-like, lose their structural integrity and will require to be replaced.

  • 1 | Woodworm infestation

Rising Dampness

Rising dampness causing wet rot to skirting board1
Rising dampness causing a tide mark above the skirting board2
Rising dampness affecting decor3

Rising dampness is the movement of water through the wall of a building by capillary action. It is common to find rising dampness in older properties where the damp proof course has failed or was never installed. However, we have come across instances in more modern properties where the builder has forgotten to install a damp proof course or the damp proof course has been damaged in the course of construction. Rising dampness can also occur when ground levels outside the property are higher than the level of the damp proof course. Rising dampness can sometimes be identified by a tidemark or salts appearing on the surface of the wall and may affect internal decoration.

  • 1 | Rising dampness causing wet rot to skirting board
  • 2 | Rising dampness causing a tide mark above the skirting board
  • 3 | Rising dampness affecting decor

Penetrating Dampness

Penetrating dampness occurs when water enters the property through deficiencies in the fabric. This can be caused by a multitude of reasons including deficiencies in lead flashings, roof tiles, gutters and downspouts, poor brickwork and pointing in solid brick walls, and debris or insulation bridging the cavity in cavity walls. Penetrating dampness causes damage to internal finishes and can lead to further defects such as rot occurring. The source of the dampness should be located and the repaired immediately.

Structural movement

All buildings move and for a variety of reasons. The vast majority of cracks in the average building are of little or no cause for concern, however some seemingly innocuous cracks can be symptomatic of something much more serious.  Settlement can be caused by changes in the property which alter the loadings on the ground or inadequate/substandard foundations. Subsidence can be caused by changing ground conditions, for example, through leaking drains, shrinking clay soil or trees.

Roof spread

If a roof structure is not adequately tied together (triangulated) or has been overloaded (e.g. light weight tiles replaced with heavy concrete tiles) the weight can cause the roof to push out or "spread". This affects walls and decoration by causing horizontal cracking to plasterwork as the walls are pushed outwards from pressure exerted by the spreading roof. Hipped roofs are most prone to roof spread and a number of developments in Northern Ireland are affected by roof spread.


Asbestos cement roof1
Floor tiles containing asbestos2

Asbestos fibres are strong and resistant to heat and chemicals which has led to their use in a wide range of building materials and products. Properties built after 1999 are extremely unlikely to contain asbestos anywhere in the building. Asbestos products are usually only a problem if they are disturbed, releasing asbestos fibres into the air. Asbestos is commonly found in textured finishes to walls and ceilings, composite floor tiles, pipe lagging, fireproof sheeting, asbestos cement rainwater goods or roofing, and roof space insulation. Care should always been taken when disturbing asbestos products and in some instances you may need to seek advice from a specialist contractor. There may be a charge for removal of asbestos products.

  • 1 | Asbestos cement roof
  • 2 | Floor tiles containing asbestos

Cavity wall tie corrosion and failure

Horizontal cracks to mortar joints caused by cavity wall tie corrosion1

The vast majority of houses built since the 1920s have cavity walls built from inner and outer leaves tied together with metal wall ties. Over time, wall ties can corrode, causing expansion of the ties which leads to tell-tale horizontal cracks in mortar joints. If the wall ties fail altogether there is a risk of the outer leaf collapsing, especially under high winds which cause suction on the face of the wall. Houses constructed between 1920 - 1950 are especially prone to this defect.

  • 1 | Horizontal cracks to mortar joints caused by cavity wall tie corrosion

Lead pipework

If your house was built before 1970 there is a risk that lead pipework supplies water to your taps. In extreme cases this can result in lead poisoning. Lead is much more harmful to children than adults because it can affect children's developing nerves and brains.

Radon gas

The single biggest source of radiation to the general public is radon gas, which seeps into homes from radioactive rocks buried deep underground. Radon will account for half of an individual's annual radiation dosage. Even so, this represents very little risk; the dosage is well within the safety limits set by the International Committee on Radiological Protection. But in some parts of the country radon levels are raised because of the local geological conditions. Radon is seen as a silent threat that you cannot see, hear, feel or taste. It is formed when atoms of uranium-238 decay and if inhaled in sufficient quantities can damage the internal lung surfaces leading to lung cancer.