Last Updated: Apr 2026 Best Dehumidifier For Loft
Do you need a dehumidifier for your loft? This is the first question that needs to be answered before we look at which dehumidifier is most suitable for your loft. Lofts do suffer from damp, but how to deal with it depends on what you use the loft space for.
If you haven’t developed your loft, the chances are your problem is condensation, caused by the warm air in your home rising. The warm air then comes in to contact with the cold roof, and condenses, and turns into water droplets. Or the damp could be caused by a loose or missing slate or a hole in the roof.
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What Happens To The Roof If Damp Is Not Dealt With?
Condensation and damp can cause other problems if they’re not dealt with correctly. Problems like:
- Wet rot
- Dry rot
- Mould
- Mildew
These can lead to structural issues like wood rot which can be particularly problematic with wooden roof rafters. If the wooden floor of the loft gets damaged by mould, rot, etc that could lead to ceiling collapse in the rooms directly below the attic.
How To Deal With Damp Problems In The Loft
With problems like these that can lead to structural problems, you need to look at structural solutions. Check the roof for loose or missing slates, check the chimney flashing for degradation and leaks. If the problem’s not damp coming in from outside, install loft insulation to stop warm air entering the loft space.
Check that any roof vents have not become blocked by boxes etc stored in the loft, insulation material, or animal and birds nests. The roof vents allow air to circulate around the loft space to prevent damp forming. If they are blocked or hindered in any way, that could be the root of your problem.
Unless you are skilled DIYer with all the relevant experience necessary to carry out these tasks, it might be a good idea to ask for expert help. Once these tasks have been completed, the damp should go of its own accord. Remember too that the whole purpose of a roof space is to allow the house to breathe, with a decent airflow.
If you fill it up with boxes etc you could be causing the problem. Once the air is flowing freely again in the loft space, there will be no point using a dehumidifier as the vents allow outside air in constantly. So a dehumidifier will never clear any damp because there is potential for more and more to be entering continuously. What about loft conversions?
Damp Problems Arising From A Loft Conversion
If you have a loft conversion, you now have extra living space in your home, but there could be a potential problem with damp. Hopefully, you used a fully qualified builder who has installed everything correctly, including:
- Dormer windows (or roof windows)
These have to be installed into the roofline and sealed correctly to prevent any water from entering the room. - Damp-Proof course
This is to prevent damp rising through the walls and causing problems elsewhere. - Roof vents
Roof vents allow air from outside to circulate and also they allow warm, damp air to escape. - Bathroom extractor fan
If you have had a bathroom installed as part of your loft conversion it is imperative that a decent extractor fan is fitted to remove steamy, warm, wet air.
If all of the above has been dealt with, then damp problems in the loft can be dealt with in exactly the same way as anywhere else in the home.
How To Deal With Damp In The Attic
If your loft space is damp, you can deal with it by using a dehumidifier to remove excess moisture. As we said earlier this will not solve damp issues in unconverted lofts because there is a constant flow of fresh air coming in through the vents. But if it’s for a converted loft then using a dehumidifier should solve the problems. Now let’s look at the best dehumidifier for lofts.
How To Find The Best Dehumidifier For A Loft
As with any other room in your home, for a dehumidifier to deal with damp efficiently in the loft conversion, it has to meet certain criteria. Let’s look at the choices and relevant features etc for finding the best dehumidifier for use in the loft.
The Size Of The Area
How large the area is that needs dehumidifying is of great importance. Because using a unit that’s too large or too small or not powerful enough for the task is counter-productive. Either it will need to be running constantly and never get to the bottom of the damp, or it will take all of the moisture from the room.
To calculate the size of the area in square metres, multiply the length by the width – That gives you the measurement in square metres. For example, a loft with a length of 4 metres and a width of 3 metres will give a square metre total of 12 square metres, and looks like this:
4 x 3 = 12
(Length x Width = 12 square metres)
Just measure your own loft room and use the calculation to determine your area in square metres.
Water Tank Size Of The Dehumidifier
The water tank or reservoir is where the water extracted from the damp air is collected. This needs to be large enough that it doesn’t need emptying every few hours, and small enough that it’s easy to handle when it needs emptying. Some models include a drainage hose that connects to the water tank as an overflow drain. This is placed in a sink or drain and allows the unit to continue running indefinitely.
Dehumidifier Capacity Rating
This is the classification system used by all dehumidifier manufacturers to quantify how much moisture can be extracted over a 24 hour period under normal operating conditions. Looking at the specifications on a dehumidifier you might find this sort of thing, water tank 12 litres, capacity 60 litres. That means that even though the unit can extract 60 litres of moisture in 24 hours, the water tank will need to be emptied after 12 litres has been extracted. This works out to every 5 hours in this example.
Automatic Start/Stop Function
Many dehumidifiers have humidistats that use sensors to measure the moisture levels in the room and cut in when needed and out once the moisture level falls below the preset amount (set by you). The sensors restart every so often to check humidity levels and start the dehumidifier again if necessary.
Trusted Brand Name
There are many manufacturers who have been around since before we were even born, a dehumidifier made by one of those companies is more likely to be reliable. You might have to pay slightly more for a well-known brand but it would be a false economy to buy a cheap model from an unknown foreign company with no customer service back-up or even an English speaking call centre.
Warranty
Most good dehumidifiers come with between a 1 to 3-year warranty often extendable to 5 years. Any guarantee is only as reliable as the company that issues it, as we said earlier buying a cheap import from somewhere on the other side of the world, made by a company you’ve never heard of is less likely to abide by any guarantees or have a customer service department.
What Type Of Dehumidifier Is Best For Loft Conversions?
There are 2 main types of dehumidifier, they both remove moisture from the air, but they function in 2 distinctly different ways. It’s not vitally important that you understand the inner workings of the dehumidifier but we’ll explain them in easy layman’s terms just so you know the difference.
Compressor (Refrigerant) Dehumidifiers
The best way to describe this type of dehumidifier is to think of your fridge. There is a coil full of a refrigerant that keeps the contents of your fridge cold. Well with the dehumidifier, that same coil of refrigerant gets hit with the warmer moist air and the water condenses on the coil and drips into the water tank. If the temperature drops too low these models can freeze and fail to function.
Desiccant Dehumidifiers
These rely on the warm, moist air passing a rotor that’s coated in a desiccant material that absorbs the moisture. As the rotor turns, it is then subjected to a blast of heat that removes the moisture that drops into the water tank, whilst the heat reactivates the desiccant ready for its next spin into the airflow. Desiccant models can work at lower temperatures to refrigerant types and are quieter too.
Both of these descriptions are simplified for ease of understanding, but they’re sufficient for our purposes here. It’s probably not going to get too cold in your converted loft, as it probably has heating, so either will work in the loft. The type is not so important in this circumstance, but the size definitely is.
What Size Dehumidifier Do You Need For Your Loft
Once you have the figure for the total area in square metres (or square feet) You are armed with most of the knowledge you need to go and get your dehumidifier. There’s just one more item of information you need, and that’s what capacity do you need. Just follow our handy guide below to work out the best dehumidifier for your loft.
| Area total in square metres | Capacity in litres |
|---|---|
| 46 square metres | 4.7 litres |
| 93 square metres | 6.6 litres |
| 140 square metres | 8.5 litres |
| 190 square metres | 10 litres |
| 230 square metres | 12 litres |
If you prefer to work in feet, you can convert these figures by using the following methods:
- To convert metres into feet
Multiply your total figure by 3.28084 - To convert litres into pints
Multiply your litres by 1.75975
Where Can You Buy A Dehumidifier For Your Loft Conversion?
All reputable major retailers sell dehumidifiers including Amazon, Argos, Appliances Direct, B&Q, Robert Dyas, John Lewis and many more.
How To Buy A Dehumidifier For Your Loft – Buying Tips
You now have all the relevant information to help you to get the best dehumidifier for your loft conversion. It’s now time to put all that knowledge to good use, here are a few pointers to help you get the best deal.
- Decide on the features that matter to you
There are many features offered with various models of dehumidifiers you need to decide if any will be beneficial to you and your home. Features include tank size, capacity, noise level, defrost, size, humidistat, etc, - Decide on the type of dehumidifier
As long as your loft is heated the type of dehumidifier is not of vital importance but desiccants are often the quietest to run and often the most energy-efficient too. - Don’t be rushed
There’s a lot to be considered, don’t rush into making your decision and never be pressurised into “one time only” offers. If one store finishes a special offer, it won’t be long before another company introduces a new offer. - Brand names and models
It’s always good to have a particular brand in mind. But some flexibility between well-known brands can save a considerable amount of cash. - Price
It might surprise you to know that just one google search can save between 20 and 30% on some models. Always check before you buy. - Warranty
All reputable companies offer warranties, sometimes retailers can add extra time to any warranty, but be careful. Take the time to read the small print before entering into any agreement with the retailer, as often they charge a high-premium and it might have worked out better to approach the manufacturer directly. - Customer reviews
Some online sites like Amazon, have excellent customer reviews, and they don’t just print the good ones. For unbiased views on the product, you are purchasing check the online reviews.
Frequently Asked Questions
You can put a dehumidifier in a loft, but if the loft has not been converted into a living space, the dehumidifier will never remove the damp as the loft space has vents to allow airflow from outdoors.
To stop condensation in your loft space you will need to be sure ventilation vents are clear and think about insulating the loft.
It is normal to have some condensation in the attic especially during cold spells.
Insulation goes a long way in stopping condensation as it prevents heat from the house to penetrate the loft space.
If the attic is not vented, any moisture that forms through condensation has no way to escape. This will eventually lead to structural problems.
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