Different Types of Damp and How to Treat Them

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The appearance of damp in your property isn’t always caused by neglect or falling behind on household maintenance jobs. It can occur from external issues out of your control.

For example, damage that occurs to property exteriors from high winds or flying debris can quickly lead to a damp problem without the household ever being aware something has gone wrong.

Some older buildings without central heating, particularly those in built-up cities that may not have seen foundation maintenance or have been affected by surrounding expansion, typically see an increased number of damp problems.

In recent years, this has also been true for many coastal properties that have had cavity wall insulation added to the building in an attempt to make homes more energy efficient.

Unfortunately, as the cavity wall had been in place to prevent moist air from causing damp problems in internal walls, filling these with insulation has caused more problems than it has solved.

What Is Damp?

If you are a new homeowner or new to household maintenance, you may not have had a lot or any experience with damp, especially if you live in a new-build property, which tend to see fewer damp problems than their older neighbours.

Damp is the term given to a build-up of moisture in your property. Often seen as a dark spot on the wall or ceiling and depending on the severity of the problem, you may even see moisture on the affected wall or ceiling.

Although visual indications of damp are the most common sign, your property may also be suffering from damp if you notice the following in or around certain rooms;

  • A musky, stale smell
  • Visible mildew or mould, typically in the corner of the room
  • Cold spots or rooms that are colder than others
  • Increased amount of condensation on cold surfaces such as windows
  • Water-stained wallpaper, usually accompanied by peeling or lifting
  • Flakey, discoloured paint, sometimes with blisters or air bubbles
  • Crumbling plaster that falls apart when you touch it
  • Spongey, decaying timber
  • Increased levels of rust around even newly placed metal fixings and fittings
  • Crumbling brickwork or missing mortar between exterior bricks

If you have been to any properties with an unknown damp problem in the past, you may recognise these symptoms, or you may see them in your own property if you suspect there to be a damp issue.

If you do notice these signs of damp, it’s important to get the problem sorted as soon as possible. Untreated damp problems only get worse.

And depending on the scale of the issue, can even lead to structural defects, and in extreme circumstances, property collapse.

What Causes Damp in Properties?

All damp is caused by a fundamental issue, the trapping of moisture in a location where it cannot evaporate. However, what causes the moist air or water to become trapped can be from a huge number of causes, including but not limited to;

  • Plumbing leaks often from old, unmaintained pipes but on rare occasions, from newly fitted plumbing
  • Lack of household maintenance leading to;
    • Blocked or broken guttering
    • Damaged external window sills
    • Missing pointing between bricks
    • Broken or obstructed downpipes
    • Missing or damaged roof tiles
  • Poorly ventilated rooms below ground level
  • Poorly ventilated bathrooms or kitchens, wherever temperatures are prone to fluctuation
  • Broken or no installed extractor fans
  • Unseen external damage, i.e. missing bricks or broken roofing sections
  • Build up of sod, soil or loose dirt against external walls above the damp-proof course

If there is any way for moisture to get into your property but not necessarily efficient enough ventilation for it to get back out or evaporate, then you are at risk of suffering from a damp issue.

It’s always worth checking over your property regularly, even if you don’t suspect damp is a problem. This ensures you stay on top of general maintenance jobs and enables you to keep your home warm and dry for your family.

If you don’t feel comfortable checking places at height, such as your roof or multi-story guttering, make sure to hire someone to do so for you to prevent injuring yourself (or worse!).

Different Types of Damp Occurring in Properties and How to Treat It

Officially, there are two recognised types of damp found in properties, Penetrating Damp and Rising Damp.

Condensation is not necessarily recognised as an official type of damp with many damp-proofing companies but if the causes of condensation are not treated, it can soon lead to further internal problems in your home.

Penetrating Damp

As the name suggests, penetrating damp is the ingress of moisture through external walls, bleeding through to internal walls and creating damp patches.

Usually half way up the wall and towards the ceiling with damp patches growing horizontally across surfaces, rather than vertically.

Coving and cornices, especially those made from timber material, may become saturated with moisture (depending on how much water is penetrating through the wall) and start to crumble or discolour.

In addition, you are likely to see the flakey or blistering paint or peeling wallpaper mentioned previously.

A strong indication of a penetrating damp problem in your home is the growth of damp patches whenever it rains, especially in heavy rain, where water can collect internally and spread throughout your walls.

This type of damp can quickly lead to more severe issues including Wet Rot, Dry Rot and structural timber decay.

Luckily, penetrating damp doesn’t usually occur from a huge issue that requires expensive repair. It’s often a forgotten piece of household maintenance that you can repair and almost instantly solve the problem, such as broken gutters or downpipes or missing pointing between external brickwork.

Treating Penetrating Damp

To treat penetrating damp in your property, first take care of the source of moisture and then dry out the walls.

There isn’t a quick fix to do this, so it’s advised to keep your property warm to allow walls to naturally dry out over time.

Where penetrating damp has been an issue for a length of time and gone untreated, some more extensive repair/renovation work may need to take place, for example, repainting or applying new wallpaper or in some extreme cases, replacing the surface level of plaster.

Rising Damp

While penetrating damp often spreads horizontally in your property, rising damp spreads vertically through internal walls, moving from floor level towards half-way up the wall and in extreme cases, reaching up to ceiling level.

Rising damp is typically the result when the damp-proof course (DPC) or membrane built into the lower half of the wall between the layers of brickwork has become damaged, is missing or has been covered up.

For example, during a garden renovation or during the addition of an extension.

The damp-proof course is a type of waterproofing used to prevent water ingress into your internal walls via capillary action in your external bricks.

It can be manufactured from a variety of materials including slate, plastic or lead-lined bitumen sheets.

In recent developments, your DPC can now be added or repaired using chemical injections into the brickwork which has reduced the need for high-cost repair jobs that call for removing bricks to replace your physical damp-proof membrane.

If you have a surveyor come around to investigate a potential rising damp problem in your property, they may advise that your damp-proof course has become ‘bridged’.

This is the term given when external materials, most commonly dirt or turf, has been piled against the external wall and the peak height is above that of the damp-proof membrane.

Although this can also occur when debris or improper cavity wall filling has been added to cavity walls, creating a physical bridge between the external and internal walls and making it easy for moisture to collect and spread.

Properties that have seen a lot of renovation work or expansion itself or in the surrounding areas can be more liable to rising damp issues as dirt and materials get shifted around during the process.

This has seen an increased number of cases of rising damp in London properties and other popular cities that have seen rapid expansion.

Treating Rising Damp

Fixing rising damp in your family home can be an extensive process. And while there are lots of ‘recommended’ fixes available over the counter in popular hardware stores that claim to offer an easy way to treat your rising damp problem.

Unless you are confident in correctly performing such a DIY task, it’s advisable to speak to a damp proofing company to take care of your rising damp problem, they will also be able to give you advice on preventing the problem occurring again in the future and in some cases, carry out repair work to areas affected by the damp problem.

If you have a damp problem but aren’t sure why the issue has occurred or aren’t confident on identifying the type of damp, it’s advisable to call upon a professional for advice.

You needn’t have to pay for expensive surveys and there are plenty of reputable companies that offer free surveys to help you identify the issue without making you feel obligated to take up their services.


Although condensation isn’t considered a type of damp that needs any special treatment or expensive repair work by itself, if condensation is allowed to continuously build up, it can easily lead to penetrating damp. Especially in bathrooms and kitchens where temperature fluctuations are common when cooking, bathing or washing.

A good method for reducing condensation build-up is to wipe down surfaces that collect moisture, for example, backsplashes, shower doors, tiled showers, bathroom walls and mirrors.

The best way to collect unwanted moisture in a bathroom for quick disposal is to use a tool like the Karcher window vac shown below. We have one at home and use it every day

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If your walls are collecting moisture regularly, this can lead to unsightly mould growth which can have an adverse effect on the occupants’ health, especially asthma sufferers.

If simply wiping down surfaces after use and cracking open a window to allow moist air to escape isn’t making a difference in your home, consider investing in an extractor fan in your bathroom or an extraction hood above your hob.

You can also invest in a dehumidifier, which is a household appliance designed to remove moisture from the air, and then set this to run in problem rooms.

It’s also recommended to dry clothing outside the home where possible, rather than on clothes airing racks or over the radiator. If you use a tumble dryer, ensure the ventilation hose leads out of the property via a window or door before making use of it.

Avoid getting down in the dumps about dampness and protect your property today by performing small household maintenance tasks ahead of problems arising, don’t forget to check your loft spaces and roof and when in doubt, always reach out to a professional for advice or guidance.