While fiberglass actually doesn't absorb moisture (the individual fibers are made from water and recycled glass), it does hold moisture, which can be very bad.
This material is made of tiny strands of glass, so it doesn't absorb water. However, when moisture fills the air pockets between the fibers, the insulation loses its ability to slow the transfer of heat.
If the source of moisture is from the inside of a wall (for example a pipe leak in the wall), and if the insulation is not dry within 2-3 days, it should be removed.
Fiberglass doesn't absorb water, so no instant damage will be done to your home's structure. However, if the problem goes unfixed, that will do damage and seriously decrease the insulation's functionality. To dry fiberglass insulation out, use a dehumidifier and some fans.
Advances in housing insulation have meant a big increase in condensation problems. Homeowners are being warned to act to prevent damp talking hold. Ironically, condensation and dampness is getting worse as homes become better insulated.
Yes, too much insulation can cause condensation. This is because over-insulating leads to poor ventilation inside a house and as a result prevents the humid air from escaping outside and becomes more prone to condense on cool surfaces and walls.
Moisture and insulation
Improperly installed insulation is one of the leading causes of condensation in the attic, especially when too much insulation traps warm air up near the roof and forces condensation.
In an ideal circumstance, cellulose insulation should take around 24-48 hours to dry.
Fiberglass, a non-biodegradable substance is resistant to mold. With its sharp, ground glass, mold spores puncture before they can attach to it. Mold can grow on the fiberglass insulation backing, which is made of paper and is a mold food source. Fiberglass insulation without backing may be the best choice.
Polyiso and extruded polystyrene foam boards have the strongest waterproof properties. What is this? Foam boards that are treated with a foil vapor barrier are the best in terms of preventing moisture from reaching surfaces. EPS is susceptible to crumbling and absorbs more moisture.
Once wet, the insulation cannot 'dry out' as it is contained in the cavity. It will then draw heat out of the property - a bit like wearing a wet jumper would take the heat away from a person's body.
Does Loft Insulation Directly Cause Damp? The simple answer to this is no. 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.
Technically, mold does not typically grow on the insulation itself. Fiberglass is not a viable food source for mold. Yet mold growth is often found on the top surface of attic insulation.
Unless you have paper backed, or wool insulation, mould does not decompose fiberglass insulation. Most often mould is found on the dust in the insulation, sometimes like the picture above the dark areas are dust caused by thermal bridging (air infiltration) and not mold.
Fiberglass insulation is constructed of tiny shards of glass that form pockets to trap air and help restrict the transfer of heat. Its naturally mold resistant in that the material itself is not a food source for mold.
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.
Because insulation keeps the heat from the escaping, the temperature of the loft, for example, would naturally stay warm. Again, many would say that this is nothing but good news, but even a warm space needs the capability to breathe and ventilate. Without this – moisture begins to accumulate.
Preventing Condensation: Use Insulation!
If using a porous insulation material, a vapor retarder is absolutely necessary to prevent the water vapor from passing through the insulation and condensing. These principles also hold true for duct systems.
If you notice any discoloration on your insulation such as brown, black, or even pink or orange particles, you are dealing with a dirt or mold problem. Insulation sheets are a solid color, so any discoloration will be obvious.
When portions of insulating material harbor mold spores, then you should replace it. Even if the material dries out, mold spores can become airborne and travel to other wet areas of the house. If you catch it early enough, then you'll only need to replace a small section of material, keeping your cost lower.
Will cavity wall insulation dry out? The answer is actually yes. It does take a long time because the materials that you use for cavity wall insulation are extremely poor at moving moisture around and allowing themselves to dry out.
Wet insulation in the attic can be dried out with the help of a fan or a dehumidifier. For some attics, you can remove the wet batts and keep them in a warm area to dry out. After a few weeks, you will need to monitor the insulation.
Does Spray Foam Insulation Trap Moisture? Does spray foam absorb water? Yes, there are open cell spray foams on the market that will absorb water, but that doesn't mean they all do. The spray foam used here at RetroFoam of Michigan does get wet and water even moves through it, but it doesn't trap moisture indefinitely.
Spray foam insulation creates a vapor barrier. This will prevent condensation from forming.