Is Insulation Waterproof? (Different Materials)

The right home insulation can save you over $200 annually on energy bills. But more than just modulating the temperature in your home, you want waterproof insulation whose performance doesn’t decline rapidly when exposed to water. The question comes in: are all insulation materials waterproof?

Insulations have varying waterproof capabilities. Insulation types like Rockwool and Amaflex are outrightly water resistant. For spray foam insulation, it depends on if it is open-cell or closed-cell. Open-cell foam insulation is not waterproof, while its closed-cell counterpart boasts impressive waterproof abilities. Styrofoam is water-resistant but not totally waterproof. Lastly, fiberglass has poor waterproof qualities.

It is easy to be overwhelmed when choosing home insulation. Yes, they are many, with varying strengths. What specific waterproof capabilities do the most popular insulation types have, and how does water affect them? Let us find out.

Is Foam Insulation Waterproof?

There are different variants of foam insulation, like open-cell foam insulation and closed-cell. The open-cell foam insulation is lighter as the cells are not closely stacked.

Such sizable pores between cells allow for increased water permeation, meaning poor waterproof capacity.

Closed-cell foam insulation has higher density, thanks to the tightly packed cells. This eliminates the openings through which water would have penetrated.

Consequently, closed-cell foam insulation has superior water resistance. Albeit, high waterproof capabilities tend to be exclusive to high-density closed cell foam insulation.

Nonetheless, spray foam insulation has impressive drying qualities when exposed to water.

Now you must be wondering how long it would take for your spray foam insulation to dry when it contacts water. Well, this depends on the level of airflow your spray foam is exposed to.

For adequately ventilated areas, spray foam insulation can dry out in 48 hours if the leak (producing the water) is small. Larger leaks can take more than seven days.

It could take weeks if your spray foam insulation was thoroughly soaked upon water exposure (typical of open-celled foam).

Despite being waterproof, we advise you don’t sustainably expose your closed-cell foam to moisture or water. Constant contact can trigger deterioration in the spray foam’s insulative capacities.

Is Fiberglass Insulation Waterproof?

Fiberglass insulation is made from little glass fiber shards. While they boast almost unprecedented durability, they don’t promise the best waterproof capacities.

When fiberglass gets wet for long, its insulating capabilities break down until the fiberglass dries. Here is what is happening.

The water molecules (consequent of your fiberglass getting wet) penetrate the pores between the tiny glass shards.

These water particles displace the air inside these spaces, which is core to the fiberglass’s insulating strengths.

With the air displaced, the material’s insulation is severely disrupted. Given its poor waterproof capacity, fiberglass insulation tends to easily drink in moisture. This amplifies the rate at which mold grows on it.

If you are using fiberglass insulation for your room, you must diligently protect it from moisture. If there are any leaks in your home’s exterior, rapidly seal them.

Should your fiberglass inevitably gets wet, you must quickly identify the affected area and dry it. You can tell which areas are affected by the smell of the batts.

Those that have interacted a lot with water could have a murky smell.

If You can’t altogether remove the fiberglass batts, you can enhance the drying by situating a dehumidifier close to the affected batts.

This should increase ventilation and dispel the absorbed moisture.

The good news is that once the moisture content is eradicated, your fiberglass regains its insulating ability.

Is Rockwool Insulation Waterproof?

Rockwool is hands-down one of the best stone wool insulation out there. It has a unique formulation that entails working steel slag, minerals, and molten rock.

The end product – a wool material strongly resembling cotton candy – is further manipulated into sheets and rolls.

Thanks to this process, Rockwool has outstanding water resistance (in addition to superior fire resistance and sound absorbency).

When exposed to water, Rockwool doesn’t wick. Typically, the water the Rockwool contacts drains off pretty quickly. This means your rockwool insulation doesn’t soak water in.

As soon as the water is completely drained and the Rockwool dries, its maximum insulation capacity is restored.

While rockwool does well against water, it is worth pointing out that it can’t resist vapor.

Is Styrofoam Insulation Waterproof?

Styrofoam is mainly produced from expanded polystyrene. Their structure is such that a considerable quantity of air bubbles is locked inside the Styrofoam.

This entrapped air buffers the Styrofoam, giving it its insulation. While Styrofoam has a closely packed cell structure, tiny air interstices exist between the cells.

Given their reduced sizes, water will struggle to soak the Styrofoam thoroughly. But when exposed for a long time directly to water, it will eventually take in water. This is often referred to as waterlogging.

Consequently, Styrofoam has water resistance properties; it will not readily absorb moisture from the air. But it is not fully waterproof.

Keeping your Styrofoam insulation submerged for long in hot tub covers or even in floating docks will soak water.

When your Styrofoam insulation is deployed sustainably in high humidity areas for long periods, it will also take in water eventually.

This harms its insulating strengths. Sustained absorption of water distorts the polystyrene pellets.

This is especially when the collected moisture stays for long in the Styrofoam and eventually forms ice.

If this happens, the Styrofoam insulation would eventually wear off.

Is Celotex Insulation Waterproof?

For those who don’t know, Celotex is one of the leading producers of polyisocyanurate boards in the United Kingdom.

A typical Celotex insulation can drop your property’s U-value (herein, the capacity of your home to transport cool air from a cold area to a warm area and conversely too), thanks to its 0.022 W/mK thermal capacity.

Celotex doesn’t absorb moisture from the atmosphere because of its design structure. Its closed cell structure lends Celetox robust hydrophobic, enabling them to shut off water even in direct contact.

Such waterproof capacity means that sustainable exposure to water leaks will not rapidly damage your Celotex insulation or facilitate mold growth.

Is Armaflex Insulation Waterproof?

Armaflex is another engineered insulation we must commend for its waterproof strengths.

A lot of this capacity can be traced to Armaflex’s elastomeric high-density structure. Armaflex is dedicatedly built to reduce condensation and consequent energy wastages.

This nitrile rubber insulation boasts high-level thermal conductivity, with corresponding high water resistance.

Its inbuilt vapor barrier ensures you don’t need to install a secondary vapor barrier when using Armaflex insulation.

Ultimately, this means longer-lasting insulation even in high humidity conditions or water leakages.

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