Dwell Well > Improving > How To Deal With Damp And Condensation

How To Deal With Damp And Condensation

Damp and condensation are surprisingly common, even in modern houses, and finding the root cause is the best way to eradicate the issue and prevent further damage or health issues.

Generally, there are three forms of damp: Rising damp, penetrating damp and condensation

Rising Damp

Rising damp is caused by dampness rising from the ground and being drawn up the wall by capillary action. Generally, a damp proof course prevents this but several defects can cause this to happen.

These are:

An old building where there was never a damp proof course fitted (circa pre-1870’s).  

A pre-1910 property where the age means the damp proof course has broken-down

Later properties where ground levels have been raised to above the damp proof course thereby effectively rendering the damp proof course ineffective. External ground levels should always be at least 150mm or 6 inches below the damp proof course

Building defects or a poor standard of works, such as: external rendering going all the way down below the damp proof course (effectively bridging the damp proof course), mortar in the cavity of a cavity wall built property (mortar can fall down and block the gap) or defective guttering

All of these problems allow water to be transmitted from the ground to the wall. Signs include:

  • Black deposits on walls or ceilings
  • Salt deposits on walls, leaving a tide mark
  • Peeling paint or wallpaper
  • A musty smell
  • Warped wood or damp timber (which, if left untreated, can lead to wet or dry rot)
  • A damp “sweat” feeling to walls

Correct identification of the cause is the first step in remedying the problem and if you cannot identify the issue yourself a surveyor will be able to provide independent advice and a cost of putting the issue right (remember that damp proof companies have a vested interest in carrying out work) Get a quote from an independent surveyor

Penetrating Damp

This is often associated with poor maintenance, generally:

  • Poor pointing (further back than 5mm from the surface)
  • Defective gutter or Downcomer
  • Cracked or missing render

All of these problems allow water to be transmitted from outside to the inside wall. Signs include:

  • Green/Black deposits on walls or ceilings
  • Salt deposits on walls, leaving a tide mark
  • Peeling paint or wallpaper
  • A musty smell
  • A damp “sweat” feeling to walls

Correct identification of the cause is the first step in remedying the problem and if you cannot identify the issue yourself a surveyor will be able to provide independent advice and a cost of putting the issue right (remember that damp proof companies have a vested interest in carrying out work)

Condensation

Modern living conditions with showers, cooking, drying clothes on radiators and double glazing combined with a lack of ventilation are common causes of condensation.

If this moisture is not controlled (opening windows when having a shower, extractor fans in the bathroom and above the cooker and ensuring dryers have an external pipe to vent the steam outside). Signs include:

  • A musty smell
  • Black mould
  • A damp “sweat” feeling to walls

Remember that dehumidifiers only remove the high moisture levels and do not cure the cause.

Correct identification of the cause is the first step in remedying the problem and if you cannot identify the issue yourself a surveyor will be able to provide independent advice and a cost of putting the issue right)

Leaks

A common cause of damp patches on ceilings is leaks from showers and baths above. The joint between a bath or shower tray needs to be water tight and if signs of a leak are showing on a ceiling below a bathroom then you should replace the flexible sealant (often called silicone sealant).

This is also the cause where you live in a flat and the flat above is the cause of leaks.

Correct identification of the cause is the first step in remedying the problem and if you cannot identify the issue yourself a surveyor will be able to provide independent advice on what works that are necessary and a cost of putting things right)

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