Drying Clothes Indoors: Cause of Damp and Mould Problems?

In this guide we will explore how drying clothes indoors can cause issues with damp and mould in your home, including delving into detail on how this can especially cause issues in winter months. We even do a test to show how quickly drying clothes indoors can increase relative humidity.

We have explained previously about how mould on walls can form and how a dew point chart can be an invaluable tool in assisting to diagnose the areas in your property at most risk.

Just to be clear – in this article we are not referring to drying clothes indoors using a condenser dryer or vented tumble dryer, but we do mean drying washing on radiators or a clothes airer / drying racks.

Why do People Dry Clothes Indoors?

There can be a number of reasons why people choose to dry their clothes indoors vs drying outdoors (or using a tumble dryer etc). These could include:

1. Poor weather conditions – for drying clothes outside (especially in the winter)
2. Insufficient or no outdoor space – for drying (for example in a flat)
3. Speed and time – especially if there is colder / wetter weather outside
4. Energy consumption / cost – as tumble dryers can be high powered items
5. Convenience / Simplicity – especially if it is just a few items you dry indoors
6. Environmental concerns – linked to the energy consumption point earlier

How Drying Clothes Indoors Causes Damp and Mould

Now that we understand why people choose to dry clothes indoors (and washing indoors) the question ins – how does drying clothes indoors cause damp and mould?

Well first of all, and this might sound obvious, but wet clothes can contain a lot of water. Anyone who has dried their washing using a condenser tumble dryer and has emptied the water tank afterwards will understand how much water can be extracted during the drying cycle. In that situation it is contained and drained away, typically down the sink.

So when you dry clothes indoors on a radiator, drying rack / clothes horse or similar that moisture typically turns into humidity in the air, which can dramatically increase the level of relative humidity in the property.

Finally, as we explained within our article about mould or mold this humidity in the air can settle on colder surfaces as condensation, which in turn can cause damp and then mould. Our handy and simple Dew Point Calculator Tool helps to explain this too.

Next we test if drying clothes indoors does actually increase humidity?

Drying Clothes Indoors – Tested

To try to prove the point that drying clothes indoors can lead to increased humidity, we put it to the test. In our controlled experiment, we took a damp towel and dried it on a radiator in a room with a hygrometer measuring the room temperature and humidity, before, during and after the test.

The results of the test are shown above in the chart showing variances in relative humidity over time. During the test, the temperature in the room was at a relatively constant 18.5°C / 65.3°F.

Here are the stages of the test where we dried clothes indoors:

1. Before we dried the clothes indoors – relative humidity was in the 55% to 58% range
2. This was over a relatively long period from 5am to 12 noon the same day
3. At 12pm we placed the damp towel on the radiator to dry it indoors
4. Within just a few minutes the relative humidity rose to above 70%
5. This represents the ‘High Risk for Condensation and Mould’ (as seen on the right)
6. The relative humidity rose to a maximum of around 77%
7. At that point we removed the towel from the radiator to see if it dropped
8. It took around 3 hours to fall below the 60% (low risk) level on the chart

Remember this was just from one damp towel on a radiator in a relatively warm house over a fairly short period of time. If that was prolonged, with more things drying in different rooms, in a colder house (with walls and ceilings with cold spots below dew point!) then this could certainly contribute to condensation, damp and then mould.

Especially if there are issues with ventilation levels and other sources of moisture – which could include a water leak. We look into this in our Bathroom Extractor Fan Calculation Tool too.

We also discuss the potential health risks of mould in our guide to problems with black mould.

Signs that Drying Clothes Indoors is Causing Problems at Home

Here are a number of things to look out for that could highlight that drying clothes indoors is causing issues with damp, condensation and mould in your home:

• Excessive condensation on windows, ceilings and walls (especially in rooms where drying occurs)
• Signs of issues with damp on walls and ceilings, possibly combined with mould too
• Higher than normal levels of humidity in your house (hygrometers can help measure this)
• Combined with the above, musty or damp smells in your home
• Clothes taking a long time to dry because of this

Interestingly, some of these are similar to the signs of a water leak in your home.

Ways to Potentially Reduce Risks of Drying Clothes Indoors

There are a wide variety of ways you can help to reduce the risks of drying clothes indoors, especially when it comes to controlling or reducing the humidity levels that can contribute to damp, condensation and mould problems in your home. Here are just a few:

• Consider other options for drying clothes (especially in winter)
• Make you you monitor humidity levels in your home
• Ensure high humidity is not prolonged to reduce the risk of issues
• Similarly, issues with cold spots which are at more risk
• Ensure adequate ventilation and extractor fans or consider a PIV unit
• Consider keeping your house warmer (to help reduce humidity)
• Us a dehumidifier if necessary to remove moisture
• Close doors to stop moisture spreading too much
• Be vigilant for signs of condensation, damp and mould
• Consider a survey to see damp causes at your home (we can help with that)

There are other options but those are a few of the key ones. Each home or business will vary so the best solution will likely too, linked to the age, construction, design and layout of the building.

Drying Clothes Indoors – Conclusion

As we have covered comprehensively in this guide, there can be a number of reasons why people choose to dry clothes indoors in the UK. However, as we have demonstrated, this can increase the risk of issues with damp, condensation and mould in your home or business, which is not desirable.

That said, if you take precautions and take measures to reduce the risks, then that can greatly help to mitigate those risks and the likelihood of the consequences occurring in your home.

As we often advise, a key piece of advice is to be aware and vigilant to some of the signs these things are becoming an issue and get help from a professional if needed.

---

Here are some other similar related to drying clothes indoors:

• Infrared Thermometer Guide
• Central Heating Leak Detection
• Anti Mould Paint
• Condensation In Loft
• Thermal Imaging Leak Detection

We have a selection of and informative guides and articles in our water leak blog which has many handy free hints and tips to assist you, this explained by experts but in simple layman’s terms, with useful diagrams, pictures, photos and charts to help understand water leaks more.

Drying Clothes Indoors – FAQs: