Condensation In The Attic And How To Prevent It: 5 Causes
Repair of the Attic

Condensation in the attic and How to prevent it: DIY

Leaks on the roof are a common problem not only in old houses but also in relatively new ones. They can cause a lot of unwanted problems. Increased moisture in the house can accelerate the aging process not only of furniture but also of the whole house.

Attic condensation can simulate a leak. Usually, the cause of attic condensation is humid air. Let’s talk about condensation in the attic and how to prevent it.

Why does my attic space have condensation?

The attic condensation that accumulates under the roof is small droplets of water. This appears due to the difference in hot air temperatures and the coating itself.

Most of the attic condensation can form on the leaking roof of corrugated board, as this material has excellent thermal conductivity.

The cooled metal comes into contact with moist warm air, and therefore attic condensation begins to accumulate on the metal surface. Excess moisture to the condensate drive. Do not forget about a frost melts, ice and snow, water droplets, and water pipes.

Water droplets on the attic floor

Common causes of condensation in attic

Attic condensation in the attic can be caused by several reasons. Let’s take a closer look at each one.

  1. Roof leak. Check the condition of your roof, as even the smallest crack lets water into the inside of the attic. As a result, the moisture level in the attic space increases and condensation forms. It is especially dangerous in winter periods, as it can form ice dams.
  2. Exhaust gases for bathroom and dryer. They should be thoroughly ventilated. All the hot and warm air should be outside. This way, excessive damp will not form. If they are not ventilated, attic condensation forms in the attic.
  3. Water pipes. If they are damaged, they can release damp, which forms condensation. Carefully check the condition of your pipes so that condensation does not form.
  4. Ventilation system in the attic. Often, the roof vents sucks in heat oxygen and water vapor and gives off dry air. If there is no ventilation system or it is broken, there is a risk of attic condensation.
  5. Lack of insulation. The attic should be isolated from bathrooms and other places with high wet insulation damp. Otherwise, rust and plaque may form on metal devices, as well as condensation.

How to identify condensation

A little above, we talked about the possible causes of condensation in the attic spaces. But now let’s lead what are the signs that you have condensation occurs and not a roof leak:

  • water flows on the walls and other flat surfaces,
  • musky, moist smell,
  • mold remediation,
  • rust and dark spots,
  • wet wood water marks and insulation,
  • windows and floor moisture.

If you look at these signs, you can easily detect condensation.

Condensation in the attic and How to prevent it: the membrane method

It is necessary to ensure constant air exchange, so that there is an inflow of outside air and the internal intake of warm moist air. Circulation of air should be carried out in the entire volume of the attic space in winter. That will reduce the relative humidity of the air and dry the condensation formed.

For air circulation, use the tips from the post What are the attic fans pros and cons – detailed manual.

Membrane usage method

Replacement of a smooth impermeable waterproofing underlay film with a special anti-condensate membrane is required.

The essence of the work of anti-condensate membranes is their ability to neutralize the formation of large droplets of damaging condensation on their inner surface (due to lintiness), as well as to let prevent moisture damage out and not let it into the improperly vented bathroom.

How membrane works

From such a film, the attic and bathroom condensate does not drip and does not drain, because its excess is filtered out of the film or dryer vents inside the attic room.

And condensate from the surface of the roofing material (roofing condensate), dripping onto the outer surface of the membrane, flows down it without penetrating inside.

By following these tips, you can be sure that there is no condensation on the inner surfaces of the attic. And a dry attic is great for storing seldom-needed or seasonal items. Here are instructions on How to make a truss attic suitable for storage.

Membrane insolation for loft

Why can condensation in the attic cause problems?

Condensation is a very unpleasant thing that can cause a lot of inconveniences. That is why it is so important to get rid of condensation as soon as possible, after you have discovered it. There are several main reasons for this:

House value reduction

The resale value of your home may decrease. Condensate contains a lot of attic moisture and moist air in attic and bathroom. It greatly affects the condition of the furniture and the house itself.

Especially if the house is wooden, the wood may become moldy and begin to collapse. Accordingly, you will either have to sell the house at a lower price or invest a lot of money in repairs. It will also appear with wet wood watermarks.

Interior and furniture spoilage

Deterioration of the structure and flat surfaces buckled. As noted earlier, condensate destroys the house at the expense of water. It penetrates into the walls musky, into the furniture. Hot and humid air provokes moisture damage everything.

When the hot and humid air, mold forms faster, which can be unsafe not only for the home, but also for health.

Health hazards

The spread of mold spores throughout the home. Purely visually, mold is a very unpleasant picture. Mold spreads very quickly and destroys many things.

Mold growth can also cause allergies and diseases. Mold can also harm the interior of the home. Try to get rid of mold immediately.

Cost when to call a professional

If you are not confident in your abilities and think that you cannot do without the help of a specialist, then contact the service. Usually roofers are hired for such work. Usually, their work costs 600-1200 dollars. A more specific price depends on the opening hours. Also keep in mind that you may have to pay up to $6,000 for the roof if there are any serious problems. After all, the ventilation of the attic also affects the life of the shingles.

But before you hire professionals, try watching this video by @diygardeninguk, it may be the key to solving your problem. As always, the cause of condensation is a lack of ventilation, and the author of the video has figured out how to fix it quickly and inexpensively.

Chapter FAQ

Why is my attic full of condensation?

The reasons why condensation accumulates under the roof may be the following factors:

Inadequate quality of the waterproofing and vapor barrier of the ceiling and the roof sheathing itself;

Lack of ventilation of the attic insulation or under-roof space of a residential building.

For each of the existing schemes of the roofing pie device, there is a reason for the accumulation of water, so it would be right to understand the mechanism before trying to get rid of condensation on the roof leak.

The appearance of condensed water on a classic roof leak.

The most common cause of condensation inside the attic is weak insulation of the roof. In this case, the dew point or the conditional separation line of the thermal insulation is located on the inside of the roofing pie. Its surface temperature in frost winter ranges from – 5oC to +6oC.

How do you stop condensation permanently?

There are several ways to stop the condensate. We have described them above. But you can also try to prevent the appearance of condensation:

high-quality installation of thermal insulation material. Insulation is quite expensive, but the cost of buying it is justified. Competent thermal insulation of the underside of the roof will not allow the formation of condensate due to the temperature difference of warm and cold air;

lead to the integrity of the waterproofing membrane. A common mistake of inexperienced builders is the installation of this material in a stretch. It should lie down freely, since with a decrease in temperature, the film narrows;

high-quality assembly of roof elements. It is possible to eliminate such a disadvantage quickly enough, but it is better not to allow the formation of such a marriage during installation;

All humidity must be properly insulated. If the roof is installed correctly, then you are not in danger of condens.

Is moisture in attic normal?

Stable relative humidity in the attic or bathroom will be almost always. Another thing is that there should be a little of it. To do this, you need to follow the installation rules and maintain an optimal humidity level in the house.

How can I increase air circulation in my attic?

You can increase warm air circulation by using open glass window panes and doors, or use dryer exhausts devices or attic ventilation system and dryer vents. It is necessary to reduce air leakage, or cool the insulation.

Vent window to attic


Lead your home for condensation. You now have an example of how to detect it. Also, now you know how easy it is to keep the water low in the attic and avoid condensation.

Remember that there are no unsolvable problems. You can always contact specialists.


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