Does damp cause humidity? Plus 3 things to look for

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does damp cause humidity

Humidity and damp often go hand in hand, and high relative humidity is the main cause of condensation in homes.

Humidity is caused by high levels of moisture in the air. Levels of moisture can also rise when the internal temperature is higher. The reason for this, is warmer air can hold more water vapour.

Due to this fact, condensation tends to be a much bigger problem in winter, when windows are closed, ventilation is poor, and the heating is turned up.

So, we have established that humidity can cause damp in the form of condensation, but can damp problems cause higher levels of humidity? The simple answer is yes, they can.

With any type of damp entering your property, you are adding to the levels of moisture inside your home. Once this water reaches internal surfaces, it can be evaporated, which will add to humidity in the air.

How to stop damp causing humidity

There are many things you can do to reduce humidity in your home, these include:

  • Improving ventilation, this can be done by opening windows, doors, air vents, etc.
  • Extract moisture. You can do this by installing extractor fans in high moisture areas, such as bathrooms and kitchens.
  • Maintain a balanced temperature, rather than going from cold to hot and vice versa.
  • Avoid high moisture activities where possible. This could include things like drying clothes indoors.
  • Use a dehumidifier to help reduce moisture in the air. You can read more about how dehumidifiers can help by clicking here.

All the above will help you reduce relative humidity in your home. However, if part of this moisture is coming from a damp problem, you need to resolve the root cause.

The first thing you will need to do, is identify the cause of damp. Remember, we are not looking for condensation damp, this is caused by the humidity. What we are looking for is water entering the property and adding to humidity.

Water can enter your property in several ways, so you will need to do some investigating to locate the exact issue. Once you have located the damp it will be easier to identify the cause. Below are three things you should consider.

1 – Is the water between ground level and roughly 1m in height?

If this is the case, there are a couple of possible causes:

  1. Penetrating damp bridging from outside
  2. Rising damp from the ground below your property.

Of the two, rising damp is the least common. Therefore, you should concentrate on trying to find signs of penetrating damp before you consider rising damp. A few things you should look for include:

  • Is there any external damage to pointing or brickwork outside? This is a common cause of penetrating damp.
  • Look for damp entering near windows or doors? If it is, check the sealant around them. If it is damaged or worn over the years this could be the culprit.
  • Is the outside ground level above the DPC? Your DPC is usually located around 150mm up from external ground level and will be visible in the mortar joint. If not, this could be the cause of damp.

You can see more potential causes and read a more detailed article about penetrating damp here.

If you have completely ruled out penetrating damp, then there is a good chance that rising damp is the culprit.

You can read more about rising damp by clicking here.

2 – Is damp in isolated patches on walls?

If damp patches are present on walls away from the floor or ceiling, this is almost guaranteed to be penetrating damp.

Again, you will need to look outside to try and find any defects that are allowing water in.

3 – Is it damp on ceilings on upper floors?

If this is away from the walls, then you almost certainly have an issue with your roof. However, if the damp is coming in where the roof meets the wall, then penetrating damp is also possible.

Again, visual inspection will be required. You should look for potential causes of penetrating damp, plus other defects to guttering and down-pipes that could be adding to the problem.

For your roof, look for evidence of common roof defects, such as slipped or cracked tiles, damaged flashing, as well as damaged pointing on ridges and chimney breasts.

Obviously, roofing is a highly skilled job and can be dangerous working at heights without the correct safety equipment, so it is highly advised you hire a roofer.

One final thing to consider.

The last thing you should look for, in all locations, are signs of faulty plumbing. Most houses have a large network of pipes running under floorboards, inside walls, etc. Even a small leak can build up large levels of moisture.

Obviously, if you do locate plumbing issues, you should get a plumber in right away to solve the problem.


So, as you can see humidity is the main cause of condensation damp. However, levels of humidity can be increased by other forms of damp, especially if the damp problems are left untreated.

Essentially, these two problems are almost always found together. Humidity can be greatly reduced by increasing ventilation, extraction, and airflow, as well as reducing moisture creating activities.

However, if damp is adding to humidity, you should always aim to fix the main cause of damp.

Not only does damp cause additional humidity, but it can also cause other problems such as damage to internal decorating and even structural issues.

Many jobs will have a DIY damp proofing solution. But if you do need help locating or repairing any type of damp, you can find affordable, local damp proofing experts by clicking here.