Loft Insulation: Costs, Ventilation & Dampness Challenges (2023)

FAQs

Does loft insulation need ventilation? ›

However, what some homeowners don't realise is that proper ventilation is needed as well. An insufficiently ventilated loft space can cause all sorts of long-term damage to the roof, especially in older properties.

Reduced Energy Efficiency

As mentioned, without proper attic ventilation, hot air gets trapped inside and causes temperatures to rise. This heat can then transfer into the living spaces within your home, making it more difficult to regulate the temperature.

The ventilation must meet the all of following guidelines. There should be a clear 50mm of air space between the insulation and the roofing felt. If roof trimmers or hips restrict the passage of air from the eaves to the ridge, you can drill a series of 25mm holes into these members to allow a continuous airflow.

To keep this part of your home in good shape and prolong its life, you must maintain good airflow in your attic. Poor ventilation can cause a buildup of hot and humid air, resulting in moisture-related issues like mold, rot and poor indoor air quality.

Pricing for attic fan installation varies depending on fan type and its location. On average, labor costs run between $100-$300 and the fan itself may range from as little as $50 to more than $500. Whole-house fans tend to have higher overall costs than attic ventilation fans.

While attic fans provide the same kind of ventilation as roof vents, there are a few downsides. If a solar-powered fan won't work for your location, you'll need to hard wire one in. Also, if the house is “leaky,” the fan could actively be pulling warm air from the home or other areas of the roof.

Disadvantages: Insulating at rafter level is much more expensive than most standard loft insulation. As well as insulating the roof, you will have to insulate any gable walls, party walls and chimneys in the loft space. If you leave these uninsulated, then the heat will bypass your new insulation making it ineffective.

Loft insulation in itself is not responsible for damp appearing in your property – however, it can be a contributing factor when it comes to the spread of damp via condensation.

Weak insulation and drafty walls

In addition to humidity issues, poorly insulated walls let in drafts, meaning your whole home will use more energy in order to maintain a comfortable temperature. Energy-efficient retrofits for your walls, attic and basement can go a long way.

Poor attic ventilation can cause all sorts of serious problems, such as ice dams, mold and mildew, and a shortened roof lifespan. Without proper ventilation, moisture can end up significantly damaging the roofing system.

Can loft insulation cause health problems? ›

There are real dangers from old loft insulation within houses, which can contain asbestos, a carcinogenic material. For newer insulation however, as long as precautions are taken during handling and installation, they will not be dangerous to the health of users.

Having too many vents in your roof can increase the chances of water leaking into your loft space and causing damage. Not enough and moisture won't be able to escape, leading to problems associated with condensation build up. The amount of ventilation required is dependent on your roof size, shape and material.

Most codes use the 1/300 rule for minimum residential attic ventilation recommendations. This means that for every 300 square feet of enclosed attic space, 1 square foot of ventilation is required – with half at the upper portion (exhaust vents) and half in the lower portion (intake vents).

It's easy to fit, water-repellent and breathable so you won't get rot or mould. Planning to use your loft for storage? Going for rigid insulation boards could save you time and effort, as you get boards and insulation in one.

What Causes Attic Condensation. There may be multiple causes of attic condensation in your house. Poor attic insulation, as well as poor ventilation, can cause your attic to trap humid air from your home. Improperly vented bathroom and dryer exhausts can also cause attic condensation.

What happens if your attic is not vented? If an attic is not properly ventilated, whether caused by a lack of vents or blocked vents, ice dams can form in winter, the HVAC system can become overworked, indoor air quality can be affected, and the roof sheathing can begin to rot.

Exhaust ventilation is most efficient when it's installed at or near the highest point of your roof where hot, humid air can easily escape. Exhaust vents are divided into three common categories: static, powered, and mechanical.

If you're not currently ventilating your attic in the winter time, you may be doing your home a disservice. Attic ventilation not only helps your home stay comfortable throughout the cold months, but it also helps protect your home from damaging moisture that can be caused by roof structures.

Roof ventilation is important year-round. During the winter, your home's roof vents allow moisture to leave the attic space, preventing the growth of mold and mildew that can occur even during this typically dry period. You should absolutely leave your roof vents open during the winter – do not cover them!

Should you put a dehumidifier in your attic? ›

Controlling this excess moisture from your attic is crucial for your health and safety. For that, a dehumidifier could be a good solution to control the excess humidity in your attic. This device can automatically control your desired humidity level and continuous drainage without any noise.

Attic fans do work. They will help circulate air in your attic and ventilate the space, so it stays closer to the outside temperature. Attics can reach incredibly high temperatures in the hot summer months and gather excessive moisture in the winter. Attic fans will help fight these problems.

Don't place insulation directly over downlights. Use a downlight cover such as a Loft Lid before rolling insulation over the fittings. Don't block any vents such as soffit vents with insulation. Don't squash the insulation as this can reduce its thermal performance by over 50%.

Much like cavity wall insulation, loft insulation is designed to last for the entire lifespan of the house, providing energy bill savings of around £250 for each one of those years that it is installed.

If you find that your old loft insulation is wet, then this may be a situation when you do need to remove it. Leaving wet insulation there and placing new insulation on top will cause the dampness to spread. This will only lead to mould, and potentially rot.

However, with regards to loft insulation, one of the best things you can do is install natural insulation made of sheep's wool. This eco-friendly form of insulation is hygroscopic, which means it's able to absorb and wick away moisture incredibly effectively, tackling condensation before it becomes an issue.

By far and away the easiest way to prevent condensation in your loft space is to install Icynene spray foam insulation. This is because Icynene battles both interstitial condensation and condensation.

Spray Foam Insulation is Ideal for Use in Crawl Spaces

Most builders and contractors agree that spray foam is a far better product for use in a potentially damp environment. Spray foam repels water, immediately attached to whatever surface you spray it on, and is resistant to biological growth.

Too much Insulation with a minimum amount of ventilation will result in condensation forming as the warm air has nowhere to escape to. It can also result from insulation being improperly installed such as too many layers being laid on top of each other or if it is too tightly packed.

Lofts can't just chip off a layer of insulation, so the need to breathe is far more important. So, can too much loft insulation cause condensation? Yes it can, and it can cause havoc in your home as well.

Can too much insulation cause damp? ›

There are occasional horror stories reported of insulation said to be causing damp issues. This shouldn't be the case when insulation is installed properly, and as long as the home was suitable for the insulation method chosen – but insulation is not the solution to an existing damp problem.

Signs of Poor Ventilation

Windows and glass that appear frosted due to condensation. The discoloration of floor, wall tiles, and grout. Early signs of rust stains on plumbing. Mold growth on structural surfaces like walls and wood.

Soffit Vents help to create a flow of fresh air into the attic or roof space of your home. Ventilation in the roof space will help reduce condensation during the cooler winter period and help to remove excess heat and any moisture during the warmer summer months.

Fibreglass insulation is also known to absorb moisture, and once it becomes damp, it promotes the growth of mildew and mould. If these spores are spread in the air, they can be harmful to human health, causing breathing problems, and being extremely hazardous to those who already suffer from allergies and asthma.

Excess insulation in the attic can make a house too tightly sealed and block vents. If airflow is blocked, moisture can't escape. If moisture accumulates in the attic and comes into contact with warm air, that can allow mold to grow, which can result in serious respiratory problems in people.

In 2011, the National Toxicology Program (NTP) removed all biosoluble glass wool, such as fiberglass used in home and building insulation and for non-insulation products from its “Report on Carcinogens.”^[3,4] California's Office of Environmental Health Hazard Assessment (“OEHHA”) published a modification to its ...

Go outside an look up at the underside of your eaves. If you can see vents then go up into your loft and make sure they aren't obstructed by insulation. If it is simply move it back from the vents and make sure there's adequate room for the air to circulate.

Finding condensation in attic is surprisingly common. It is estimated that at least 1 in 5 homes are affected by this issue. First tell-tale signs include finding damp in loft or water accumulation on the inside of roof tiles or roof membrane.

If you find that your loft space is too humid, you can use a dehumidifier to reduce the humidity. A dehumidifier will not work in an undeveloped loft space because it will be taking the fresh air that comes from under the eaves, which is very inefficient.

What Is the 1:300 Rule? The US Federal Housing Authority recommends a minimum of 1 square foot of attic ventilation for every 300 square feet of attic floor space, evenly split between intake and exhaust.

What is the most effective way to vent moisture from an attic space or under a roof? ›

Insert Roof Vents

Roof vents are typically set at a roof's peak, where the attic's air naturally rises. Adding roof vents to your attic can ensure warm, moist air is able to escape, preventing heat buildup and condensation. You will need to periodically check your roof vents to make sure they are debris free.

The IRC requires 1 square foot of net free ventilation area to every 150 square foot of attic floor space (1/150), but does not specify the location of intake vents or exhaust vents, nor does it specify the ratio of intake to exhaust.

Does insulation make your house hotter? "Insulating homes has very little, if any, impact on the risk of overheating," said Professor Kevin Lomas from Loughborough University, who led the largest national study so far into overheating in homes.

Since 2003, current building regulations recommend a depth of at least 270mm (mineral or glass wool) in the loft – use this as a starting point rather than a finishing line to see larger savings. In 1995, the recommended depth was 200mm. Prior to that it was less than 100mm.

Can you put a dehumidifier in the loft? A loft dehumidifier, much like a basement dehumidifier, aids in preventing condensation, dampness, and moisture damage in your attic. Moisture that is trapped in a loft can harm stored things and result in dampness, mould and mildew, bad odours, and property damage through rot.

There are three general reasons why humidity can become high in an attic: 1) poor ventilation; 2) improper insulation; and 3) heated air from living areas getting into the attic.

Air sealing an attic goes a long way to maintain your home. Besides keeping energy costs low, it'll mainly help to keep your home feeling comfortable long-term. Without a sealed attic, hot air can get inside the living space (heat gain) during warmer months and get outside (heat loss) during colder months.

Condensation building up in lofts and roof spaces has become an increasingly common problem for property owners in recent years, and if you don't notice it early and take action that condensation can lead to serious issues like damp, black mould, and your timber starting to rot.

The Solution. I've found the most effective way to cure loft condensation is to install ventilation so a breeze can enter the loft and pull the moisture out of the loft into the atmosphere (this method works for most lofts in the UK but not “warm roofs”).

If the fibreglass insulation is found wet, remove the affected area and place it in a warm place to dry out naturally with lots of ventilation. Once dried, you can install the fibreglass insulation back in place. If this is not possible you will have to throw the insulation away and replace it.

Is it cheaper to run an attic fan or air conditioner? ›

Attic fans are more energy-efficient than air conditioners, as they'll typically use no more than 10 to 15 percent of the power needed to run an air conditioner, making an attic fan a more affordable cooling option.

The ideal attic temperature should be no less than 60 degrees in the winter and no more than 10 to 20 degrees above the outdoor temperature in the summer. If your attic temperature climbs above 130 degrees, you may start running into issues with your energy bill, as well as the integrity of your roof.

This ventilation space is incredibly important for a cold deck roof as otherwise when the warm air passes through and changes temperature, if it can't escape it produces water droplets which can then cause damage to your ceiling.

If you're concerned about attic temperature control, a specific attic temperature range should help. Make sure your attic is no colder than 60 degrees Fahrenheit and no warmer than 10 degrees above the outside temperature.

We recommend a FFP3-rated disposable dust mask when working in the loft, especially when handling or cutting loft insulation. Look for ones with a valve for easier breathing.

One important thing to remember is that insulation should never be pushed right into the eaves because it will interfere with airflow. If you're going for a warm loft then you'll need much more insulation to be able to cover the underside of the roof along with the gable and party walls.

Water vapour entering the loft increases the risk of condensing at the inside of the roof slope or other cold surfaces such as water tanks. To reduce the chance of condensation, you need to increase ventilation in the attic to try to remove the water vapour that is generated before condensation occurs.

Too much Insulation with a minimum amount of ventilation will result in condensation forming as the warm air has nowhere to escape to. It can also result from insulation being improperly installed such as too many layers being laid on top of each other or if it is too tightly packed.

As long as you ventilate your property properly, you can have as much insulation as you like within reason. The trick with loft insulation is to balance the amount of insulation you have with the amount of ventilation necessary to prevent damp. As long as you get that balance right, you should be fine.

Placing boards over your insulation can be a great idea if done correctly. By boarding over your loft insulation, you can create a lot more storage space whilst creating a safe and stable environment.

Is it OK to sleep in a room with exposed insulation? ›

"Fiberglass insulation should never be left exposed in an occupied area, according to the American Lung Association," says ALA's Godfrey. "Exposed fiberglass insulation, once in the air, does cause respiratory reactions, such as dry, scratchy throat and coughing, as well as acting as a skin and eye irritant.

Since 2003, current building regulations recommend a depth of at least 270mm (mineral or glass wool) in the loft – use this as a starting point rather than a finishing line to see larger savings. In 1995, the recommended depth was 200mm. Prior to that it was less than 100mm.

The general advice we give is that you should always insulate between and above the rafters (warm roof) or between and under the rafters (cold roof).

In most circumstances removing your old insulation isn't necessary and it can actually be quite beneficial to leave it. This is as most insulation will retain its thermal properties so leaving it in place will mean that you continue to benefit from it whilst also having an additional layer of insulation on top!

In the Summer: On a hot day, touch your ceiling with your hand. If it feels warm, this is a tell-tale sign that your attic is storing hot air. This interferes with your home's ability to stay cool and comfortable and shows that more ventilation is needed.

The Solution. I've found the most effective way to cure loft condensation is to install ventilation so a breeze can enter the loft and pull the moisture out of the loft into the atmosphere (this method works for most lofts in the UK but not “warm roofs”).