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Penetrating Damp

Damp Control for your Home

Penetrating Damp

Penetrating damp is essentially an issue with water being unable to escape and is usually caused by one of two scenarios; either a problem with the building/plumbing issues or wind driven rain, hence the alternative name of ‘rain penetration’. However, as with many damp problems is can be difficult to identify and may also be mistaken for other types of damp, rising damp in particular.

Here are a few of the telltale signs you may have an issue with penetrating damp: 

  • Plaster and paint damage – the appearance of blistering and stains.
  • Rot and decay on skirting boards and woodwork.
  • A mouldy damp smell and possible appearance of mold on internal walls.
  • Excessive moss growth on external walls.
  • Damage to bricks and mortar.
  • Blotchy patches on internal walls.

When looking at options on how to repair the penetrating damp the first step is to diagnose where the problem is coming from. There are a few areas you as a homeowner can check to identify the route cause.

  • Check downpipes, guttering, flashing, rendering and window frames for blockages and obstructions.
  • If you have a localised internal damp patch check the external wall for damaged or cracked bricks and mortar.
  • Inspect your household appliances such as dishwashers/washing machines and plumbing regularly for possible leaks or faults.
  • Look carefully around your window frames as damp patches could indicate a gap which will need to be sealed.
  • If your ceiling gets damp patches after a heaving rainfall this could indicate missing or damaged roof tiles.
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Any damage to the brickwork or building can usually be easily repaired by a reputable builder but for long term protection you will need to speak to a damp proofing professional. One option may be ‘wall tanking’. This is a generic building term for coating or lining walls to seal them against water. Tanking materials, such as liquids or membranes, are applied to either the external or internal walls of the building.

Damp Proofing Frequently Asked Questions

Damp in the home or ‘structural damp’ is essentially unwanted moisture in the structure of the building which can result from factors both internal and external to the property. Essentially, damp is excess moisture and this excess is either caused by a sudden increase in the amount of moisture entering the building or the usually gradual buildup of moisture inside unable to escape.

Not only does damp look unattractive but it can also lead to serious health problems.  Unwanted moisture can enable the growth of fungus in the wood causing rot and mould. Moulds can grow almost anywhere, on virtually any surface and can cause poor indoor air quality leading to sick building syndrome and/or respiratory problems.

Every building, no matter the age or size will contain some moisture from not only the air within the property but also the building materials used in construction. Moisture naturally spreads from wet to dry areas and gravity also pushes it downwards – the construction of your home should allow for this. However, problems do still occur so it’s vital to keep a look out for the early signs of damp.

Signs of Damp to look out for

Damp may not always be easy to spot but there are a few key indicators that should raise alarm bells:

  • A damp or musty smell
  • Discoloration of walls and ceilings
  • Mould or mildew forming on walls
  • Wallpaper lifting, peeling, straining or blistering
  • A general chilly or damp feeling
  • Algae, salt stains and/or mould on external walls
  • Decay of timber and possible presence of fungi or wood boring weevils
  • Excessive condensation on windows
  • Rusting of nails, screws and/or the angle beads within the plaster work
  • External mortar beginning to crumble away

If you are concerned you may have a damp problem contact us for some further expert advice and guidance.

It is actually a common misconception that damp is caused by one single factor when in fact it can be several, each requiring an expert diagnosis and solution. There are three common forms of damp;


Condensation is by far the most common form of damp in the home. It is essentially caused by warm air which contains water vapour being cooled. Warm air can hold more water than cool air so when warm air comes into contact with a cold surface such as glass or cold walls it can no longer hold onto its moisture content. This is called the ‘dewpoint’ and is when the water begins to drop out of the air causing condensation. Common sources include laundry, bathing and cooking. In the United Kingdom we even have a ‘condensation season’ which runs from October to March and this is when problems are particularly common. You can read more about condensation, the effects and what to look for here.

Rising Damp

Rising damp is the term used when groundwater rises up through floors, walls and masonry. It is not as widespread as other types of damp but is certainly not a myth like some claim. This type of damp has been a well observed problem in buildings for over two hundred years, in fact it may have even been a problem that the Romans and Greeks had to deal with. The problem lies in the fact that bricks and mortar contains many fine capillaries and is therefore very porous. The moisture in rising damp continues to rise until it can evaporate or the pores become to fine to allow it to continue. Most modern properties are fitted with a Damp Proof Course (DPC), this was compulsory in walls post 1875,  but some homes have no DPC or it may even have failed. Read more about rising damp and what signs to look for here.

Penetrating Damp

Also known as ‘rain penetration’ is another common form of damp which can often be mistaken for rising damp as it frequently occurs at ground level. Penetrating damp is essentially caused by water leaking through walls and being unable to escape.

Caused either by the lack of an escape route for moisture entering the structure, or an increase in moisture that overloads the escape route. It can often caused by defective building or plumbing work such as leaking gutters or roof work and cracks in walls which result in the walls regularly being soaked with water. Modern buildings offer more protection from penetrating damp than older properties due to their cavity walls.  Find more information on penetrating damp and what signs to look for here.

Other Types of Damp

There are other less common types of damp including Chemical damo which is when the plasterwork is contaminated with hygroscopic salts. These salts then absorb moisture direct from the air.  Or you may have damp caused by a corrosion in the buildings plumbing, often occurring often when joints are not made fully watertight.

You may even be thinking your damp problem does not fit any of these descriptions or you may have a combination of several different types of damp if so contact us for some friendly expert advice and further information.

Damp in the home can be caused by various factors, some more obvious than other. If you notice any signs of damp in your home the first step will be to contact an expert to help identify the type of damp problem you have. If you own an older property you will need to be extra vigilant as they tend to be much more susceptible to damp due to the types of materials used in construction and the complete lack of dampproofing.

Other key issues and  causes of damp in the home include;

  • Plumbing problems – sometimes difficult to see but can cause a regular, concentrated escape of water which can overload the surrounding area.
  • Leaking or undersized gutters – A leaking gutter can feed water onto the walls, windowsills and the roofing area. An undersized gutter will allow the rainwater to overflow and saturate the walls.
  • Holes in roof – possibly from a missing or slipped tile which will allow water to leak into the building.
  • Modern plaster, paint and wallpapers – they can be impermeable and prevent moisture moving through the walls to escape.
  • Converted cellar rooms – most cellars are part of the moisture control within the home but when they are not properly ventilated during conversion it can force moisture up into the other rooms of the home.

Damp proofing is a generic term for the process of protecting your property from moisture passing through the walls and floors. Damp proofing can be done by several different methods and treatments but it essentially places a barrier in the walls or floor to prevent the various types of damp that may be occurring.

There are several different types of damp proofing including;

  • A damp proof course (DPC) – most homes are constructed with a DPC but this can become damaged or may be faulty.
  • Cavity wall construction – most modern homes are built with an exterior wall separated from the interior wall by a cavity.
  • Surface coating – when a thin water proof material or cement is applied.
  • A damp proof membrane (DPM) – a membrane which is applied to prevent moisture transmission.
  • Integral damp proofing – this is when a substance is applied to the concrete mix to make it impermeable.

Whatever your damp problem the first step will always be to speak to an expert at JRM cellar conversions. They can help you diagnose your damp problem and talk through the best damp proofing solution for you and your home. Damp is always dealt with best if dealt with early so do not hesitate to contact us.

We cover all areas in West Yorkshire for Damp Proofing

Batley - Bingley - Bradford Brighouse - Castleford -  Cleckheaton - Dewsbury Halifax - Haworth - Hebden Bridge - Holmfirth -  Huddersfield - Keighley Leeds - Morley - Normanton - Ossett - Otley - Pontefract - Pudsey  - Rothwell -Shipley - Sowerby Bridge - Todmorden Wakefield - Wetherby - Yeadon