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Myth Busting: How Effective are Dehumidifiers?

If your property is suffering from a damp problem, the use of a dehumidifier will only help to contain the problem as opposed to damp proofing your home - the more permanent solution.

Sadly, there is no quick fix or instant, magic solution when it comes to damp. Dehumidifiers are a valuable tool in preventing damp, but they will not resolve the issue. If your property is suffering from a damp problem, it needs to be solved at every level, from stubborn symptoms right the way down to the underlying root cause.


What is Humidity?

In its simplest form, humidity is literally just moisture in the air, usually caused by evaporation of water. It can be caused by anything from global weather patterns to taking a long, hot shower, to just making several cups of tea.

There are two main ways to measure humidity - relative and absolute. Absolute refers to the absolute amount of water in a given measure of air, usually in grams per metres cubed. Relative humidity refers to a complex set of variables linked to everything from air pressure to temperature of the air to the temperature of the environment. This measure is usually read out in percentages or fractions. What is important to understand is that the closer the number is to 100%, the closer the air is to the so called “dewpoint” where water will condense.

How are Humidity and Damp Connected?

It is important to understand that humidity inside a building is a symptom of damp, not the cause. Water in the wrong place in your building could be happening because of all kinds of reasons. Maybe your guttering has failed, or weather damage to your roof has let rainwater get in.

These reasons all mean that the air in your building is in contact with more moisture than it should be. This creates humidity as the natural ambient heat of your home gently evaporates water, allowing it to spread out into the air.

This vapour-filled air can then condense on colder objects, further spreading water damage, but also creating ideal environments for mould spores to settle down and grow.

Do Dehumidifiers Help With Damp?

Dehumidifiers pull the air in your home through their filtration systems, extracting the water then expelling clean, dry, pristine air. Dehumidifiers are widely used for all kinds of issues, ranging from allergies to quarantine procedures, as they provide a deeply valuable and functional service to make sure air is dry, clean, and safe.

However, as much as this is an important process, it does not stop mould from growing, and it will not eliminate damp.

Why Doesn’t This Stop Mould?

Firstly, dehumidifiers are not perfect. In fact, they only tend to drop humidity levels to below 50% to 60%. They do not eliminate humidity completely.

To make the air completely and utterly bone dry, you would need a much more comprehensive solution, and even if you could do it – it may not actually be desirable. A small amount of moisture in the air is healthy for a generally pleasant environment.

Secondly, dehumidifiers cannot filter all the air in your property. Every building will include several spaces of what is called “dead air” - places where there is very little movement, activity, or change. Behind shelves, under sofas, and between cupboards are good examples of these kinds of spaces. Because of this, the moisture and spores that collect here will likely be spared from the air purification that a dehumidifier will offer.

As more spores and moisture collect, condensation and mould sprouting is inevitable. The only way to effectively combat this is to design your spaces with either as little dead air as possible or mark out the spaces where this air might be and move things around regularly.

Thirdly, even if multiple dehumidifiers were able to eliminate almost all the moisture in the air, that would only stop new collections of spores sprouting into mould on other surfaces. It wouldn’t kill the existing mould, as that can only be removed with thorough cleaning. Unfortunately, mould is deeply resilient and needs only the most limited supplies of water to survive.

Most importantly, dehumidifiers only deal with water once it is in the air and they can't stop water from entering the air in the first place. The only way to resolve this problem is with a comprehensive overview of the building, its construction, design, and environment. Only by examining these factors can you determine the true origin cause of the water that is the source of your damp problem.

Last but not least, dehumidifiers do not last forever. As they extract spores and moisture from the air, mould can build up inside their own systems instead. While they can be cleaned and maintained to help extend their functional life, the reality is that they will need to be replaced at some point.

What Else Can Stop Mould Spreading?

Maximising ventilation is important in order to limit potential problem patches of dead air. If spores are blown about, they cannot settle and they cannot flourish. They also cannot stay. They will be expelled outside, where they can settle much more harmlessly.

However, the most important way to stop mould is at the source. At Garratt’s Damp & Timber, we provide a permanent damp proofing solution for your home, saving your property from damage resulting from the build-up of mould and dry rot.

For more information on the services that we provide, or to request a quotation, please call our team today on 0208 535 7536 and we will be happy to help.

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