Moisture in the house in summer: how does it happen and what can you do?

As soon as the temperature rises and the sun shows itself more often, we don't usually think about moisture problems. Yet moisture in the home in summer is more common than you might think. Warm air can hold a lot of water vapour, and when this air cools in the house, condensation forms. This can lead to mould, musty odours and even damage to your home.

But how do you know if you are dealing with this? And more importantly, what can you do about it? In this article, we answer frequently asked questions about summer damp problems.

08/07/2025

Why do you suffer from moisture in your home in summer?

Although summer seems dry and hot, plays humidity a big role. Warm outside air often contains a lot of moisture. When this air enters your home and cools there (e.g. by air conditioning), the moisture settles on cold surfaces. Think of walls, windows or floors.

There are also other causes of moisture in the house during summer:

Bad ventilation in combination with warm, humid air. In summer, the outside air is not only warm but also contains a lot of moisture . When this warm, moist air enters your cooler home and comes into contact with colder surfaces, the air suddenly cools. As a result, the air "releases" excess moisture in the form of tiny water droplets, or condensation.

Moisture production indoors from showering, cooking or washing. We ourselves produce a significant amount of moisture in the home. An average family produces between 10 and 15 litres of moisture every day, simply by living. By not ventilating enough, this moisture production can also lead to problems.

Rising damp from crawl spaces or cellars. When the water barrier is missing, damaged or has lost its function, moisture can migrate upwards through the wall. The bricks and masonry suck up the moisture, and capillary action causes it to gradually rise up into the structure.

Penetrating moisture for poorly insulated exterior walls. It can also rain heavily in summer and warm temperatures. When exterior walls are exposed to rain for long periods, they can become saturated. If the facade is porous or damaged, this moisture will eventually penetrate the entire thickness of the wall and become visible on the inside.

How do you recognise moisture problems in your home during summer?

Moisture problems in the home are often less likely to be noticed during summer. They develop more slowly, and because people air out more often or are home less, the signs sometimes go unnoticed. Nevertheless, you can recognise them by the following signs:

There is regular condensation on windows, mirrors or walls, even in hot weather

There is a lingering musty smell in certain rooms

You see moisture spots on walls or ceilings

Mold forms in corners, on ceilings or behind furniture

There is a heavy or muggy air, especially in poorly ventilated rooms

Tip: Use a hygrometer to measure the humidity in the home. A healthy percentage is between 40 and 60%. If you're above that, it's time to take action.

How can you prevent moisture in your home in summer?

Prevention is indeed better than cure. However, when you find that basic prevention tips are not enough, it is often a sign that there is a deeper, structural problem. A specialist such as Aquaconsult will look beyond the symptoms and tackle the cause.

1. Ventilate smartly and purposefully

Try to regularly ventilate early in the morning or late at night. At these times, the outside temperature and absolute humidity are at their lowest. This can be done in several ways, by the way:

Shock ventilation: open windows and doors wide for a short, powerful flow of air (15-30 minutes). This is more effective than leaving windows ajar all day, which actually lets in warm, humid air.

Cross ventilation: open windows and doors on opposite sides of the house for maximum flow of fresh air.

Balanced ventilation: a ventilation system type D, also known as balanced ventilation, controls the air supply and exhaust completely mechanically. It ensures a perfect balance of air flows and offers maximum control over ventilation, something that is not possible with other systems.

2. Use a dehumidifier

In spaces that are naturally moister and cooler, such as the basement, laundry room or bathroom, a dehumidifier is a very effective tool. The device removes excess moisture from the air, lowering humidity and reducing the risk of condensation and mould. However, this is not always guaranteed.

3. Reduce moisture production in the home

You can partly prevent moisture problems by producing less moisture in your home. Some tips:

Preferably hang laundry outside. If you use a tumble dryer, make sure it drains well outside. With a drying rack: place it in a well-ventilated area and open a window if necessary.

Always turn on the cooker hood to drain cooking juices immediately.

Take shorter, less hot showers and ventilate well afterwards. Open a window or turn on mechanical ventilation until the vapour is gone. Pull the shower walls and floor dry with a squeegee.

When should you call in a professional?

The basics of ventilation and limiting moisture production are an excellent first line of defence. But what if problems do crop up? Some causes are deep in the construction of your home and more persistent than you can fix yourself. If you recognise any of the following signs, it is a clear sign that it is time to call in a damp proofing specialist like AquaConsult:

Persistent moisture spots, despite good ventilation

Recurring mould or musty odours

Suspected rising damp or leaking damp

Problems in the basement or crawl space

An expert can determine the cause via moisture measurement and inspection and provide an appropriate solution, such as injection against rising damp, basement waterproofing or façade impregnation.

Get assistance from AquaConsult

Moisture problems are not just a winter problem. Moisture in the home during summer is more common than many people think, and can lead to unhealthy situations and damage to your home. With the right knowledge, good habits and, if necessary, professional help, you can keep moisture in check, even in summer temperatures.

Are you suffering from moisture problems? Ask now a free moisture expertise to AquaConsult.

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