In fact, adding too much insulation to your walls can lead to problems such as poor ventilation, mould growth, and condensation. This is because thicker insulation can block airflow and trap moisture, leading to indoor air quality issues and even structural damage.
It is possible to over-insulate your house so much that it can't breathe. The whole point of home insulation is to tightly seal your home's interior. But if it becomes too tightly sealed with too many layers of insulation, moisture can get trapped inside those layers. That's when mold starts to grow.
Your walls or floors are always cold. Your home is drafty, especially in certain areas. You notice water leaks or moldy insulation, especially in attic spaces.
The Short Answer
If your house has too much insulation, it becomes too tightly sealed, and moisture becomes trapped inside. If there isn't proper ventilation, especially in the attic where the warm air travels when it rises, mold will grow, and your home's air quality can decline.
Many of us know what causes mould; when moisture is trapped in the rooms of you home. Sometimes, there is insufficient insulation in the walls, so mould grows. However, not many people realise that additional insulation isn't always the answer. In fact, too much insulation can be the secret cause of mould.
The short answer is, yes, you can over-insulate your home. While your home should be well-insulated against the cold and keep you cool during hot summer months, that doesn't mean you should cram the walls full.
The PROBLeM wiTh MOLd
Mildew (mold in early stage) and molds grow on wood products, ceiling tiles, cardboard, wallpaper, carpets, drywall, fabric, plants, foods, insulation, decaying leaves and other organic materials. Mold growths, or colonies, can start to grow on a damp surface within 24 to 48 hours.
As a general guideline, it's advisable to install double layers of thermal insulation throughout your house. Nevertheless, this may not be feasible in all areas due to space limitations. Typically, it's not practical to add two layers of insulation within the walls of your home.
The optimal R-value for most homes is 30, but you can go as high as 38 if you live in a tropical climate. Anything higher than 38 indicates an over-insulated space. While you might think that too much insulation can't be bad, there are some significant consequences to consider.
Never place insulation close to water heaters, oil burners or anything hot. The backing is especially flammable and will be a major fire hazard for your home.
One sign of good insulation is having even temperatures throughout your home. If different rooms have different temperatures – say, you freeze in the kitchen but feel too warm in your living room – that's a clear sign your house is under-insulated.
Depending on where you live and the part of your home you're insulating (walls, crawlspace, attic, etc.), you'll need a different R-Value. Typical recommendations for exterior walls are R-13 to R-23, while R-30, R-38 and R-49 are common for ceilings and attic spaces.
Exposure to some insulation products can cause certain health effects if the product is mis- handled, mis-applied, or if the wrong product is used in certain environments. Common symptoms may include irritated, itchy, watery, or burning sensation of the eyes, nose, or throat, or itchy skin or skin rashes.
Lifespan of cavity wall insulation materials
Polystyrene beads can last up to 100 years due to their resistance to moisture and decay. Polyurethane foam and mineral wool are durable, typically lasting over 50 years. Extruded polystyrene (XPS) has a 20—to 30-year lifespan, and fibreglass can last 80—to 100 years.
Good interior wall insulation reduces the risk of moisture problems by slowing heat transfer and regulating temperatures. Depending on the wall's location and your climate, you might benefit from adding a vapor control layer (VCL).
Thicker walls generally have a lower U-value, which means they offer better thermal efficiency. For example, a 600mm thick solid wall has a U-value of 1.6W/m2K, while a 300mm thick wall has a U-value of 2.78W/m2K. The goal of adding external insulation is to reduce the U-value, thereby improving thermal efficiency.
According to the U.S. Department of Energy, R-values for exterior walls in colder climates should be at least R-13 to R-23. In milder climates, a lower R-value may be sufficient. For example, in a moderate climate, an R-value of R-13 to R-15 is typically recommended.
One common cause of reduced ventilation is improper insulation. If insulation is installed too thick, it can block ventilation and trap moisture, leading to a host of issues such as reduced air quality and the growth of mold.
If we wish to label the strength of the association, for absolute values of r, 0-0.19 is regarded as very weak, 0.2-0.39 as weak, 0.40-0.59 as moderate, 0.6-0.79 as strong and 0.8-1 as very strong correlation, but these are rather arbitrary limits, and the context of the results should be considered.
R-value is used to judge thermal insulation performance and the higher the number, the better the product's insulating ability. So R19 has better insulating ability than R13. Now R-Value ranges widely across products and home applications.
The DOE Insulation Fact Sheet (DOE/CE-0180) can be ordered from the Energy Efficiency and Renewable Energy Clearinghouse or accessed from the Internet at www.ornl.gov/ roofs+walls. Fiberglass and rock wool batts—2x4 walls can hold R-13 or R-15 batts; 2x6 walls can have R-19 or R-21 products.
The thermal barrier of a home should consist of a continuous layer of insulation on all sides—including the lowest floor, the exterior walls, and the ceiling or roof. Doubling the thickness of insulation will double the insulation's R-value, cutting heat loss in half.
Generally speaking, closed-cell insulation (i.e. cellular glass, phenolic, polyiso, and flexible elastomeric foam) is more resistant to mold spores than open-cell insulation (i.e. fiberglass).
The only way to prevent mold infestation in drywall following a water damage incident is to dry it within 48 hours after water intrusion. The 48-72 hour window is critical to prevent mold growth as it usually takes 24 to 48 hours for mold to germinate and grow.