Does Great Stuff Spray Foam Absorb Water?

Does Great Stuff Spray Foam Absorb Water?

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Does Great Stuff Spray Foam Absorb Water?

Great Stuff spray is a brand of expanding foam insulation that seals and insulates gaps in walls, doors, windows, and ceilings.

Yes! If you find a leak in your roof or plumbing system. Great Stuff will keep your home dry and safe from potential mold growth.The active ingredient is polyurethane foam that expands to fill the space between surfaces as it hardens.

You can buy this product at your local hardware store or online. Great Stuff’s original formulation came out in 1959.

It was initially marketed as an easy-to-apply home improvement solution for homeowners looking to “Do It Yourself” projects at home.

However, there are now many Great Stuff sprays available on the market today that have varying degrees of expansion properties depending on the job you’re doing.

Great stuff spray foam has proven excellent for new construction and remodeling projects because it’s more than an insulator.

– It also provides structural support by filling gaps between surfaces like wood studs and joists where the air can enter the home through leaks.

– It’s also an effective sound barrier. Thus homeowners living near busy streets or airports will appreciate how quieter their homes are after installing this product.

What Spray Foam Is Waterproof?

Closed-cell polyurethane spray foam is waterproof. Some open-cell spray foams may also be water-resistant but not waterproof.

When closed-cell polyurethane applies to a substrate and cures fully.

It will form an air barrier that makes the assembly air and moisture-proof and reduces vapor transmission (indoor condensation).

During the entire surface curing process, any excess bleed water from the substrate or from within the foam cells must have time to escape so that when the foam has fully cured.

There’s no longer any pressure difference between inside and outside of the created wall system thermal boundary.

If this does not occur, water vapor will enter via capillary action, where it can find a path through small fissures and capillary pores.

The now water-saturated foam cells are impervious to vapor transmission further when the pressure difference is no longer present after full curing.

Suppose there’s a path for moisture penetration into your home or building envelope via the substrate you’re spraying.

In that case, you must address this before applying closed-cell polyurethane spray foam.

On substrates where it would be undesirable for water to penetrate behind the surface.

You will still have some risk if you decide not to apply an appropriate primer coat before spraying closed-cell polyurethane over these types of materials.

The top surface may appear sound, but only time will tell if there was ever enough time for all excess bleed water from beneath the surface to evaporate.

It’s never 100% known if all moisture is fully eliminated beneath the substrate. This is even after drying for days, weeks, or months.

There may be enough time to cover your flooring with polyurethane before the residual moisture below fully evaporates (causing no problems).

There may not be enough time (in which case you’ll get swelling and flaking – turning your beautiful floor into something that resembles drywall).

If you’re planning to use closed-cell spray foam in areas where water will come in contact with an untreated substrate.

Does Great Stuff Spray Foam Absorb Water?

It would be best to spend some extra money on a good primer coat of open-cell spray foam first.

If water gets behind an open-cell foam, it can still eventually evaporate out after about a week or two, causing no problems.

Once the open-cell foam has sunken below the water’s surface, then you’ll have no issues with anything that it’s in contact with – including your substrate.

Is Great Stuff Big Gap Filler Closed Cell?

Yes! Because the Great Stuff Big Gap Filler is a closed-cell, you cannot use it as a gap filler. The product can fill gaps between the wood, plastics, and metal surfaces.

Also, this product has been thoroughly tested for durability. This is to ensure that it will last in spaces where people live or work. A few of its features include:

• No shrinkage, so you don’t have to worry about your project expanding

• Easy clean up with soap and water if it gets on carpets or other textiles

• A variety of sizes available to fit different sized gaps

Does Expanding Foam Stop Damp?

Yes! It seals off small gaps where moisture can enter your home by forming an airtight seal at the base of the wall or ceiling.

One can use expanding foam to insulate buildings with limited cavities, such as timber-framed homes, where mineral wool insulation or cavity wall insulation would be unsuitable.

It’s also ideal for filling the gaps around things like plug sockets and light switches. When expanded polystyrene mixes with air, it grows 30-60 times its original volume.

This fills all the gaps in the building’s structure.

Once dry, this foam completely seals off small openings and cracks against air leakage, damp penetration and helps protect against noise pollution.

Expanding foam doesn’t cure until open to the atmosphere.

Thus once applied can continue absorbing moisture until it becomes water-resistant (it won’t suddenly stop blocking out dampness).

Some formulas are more tolerant of wetting than others. However, reapplying may be necessary after drying out if you expose the area to water during the application.

Will Great Stuff Foam Lift Concrete?

No. The expanding gas causes the foam to rise off any surface. Some people believe the foam will lift the concrete, but that is not possible because of all the pressure built up in between.

The expanding gas creates a lot of pressure inside each pocket. With enough pressure pushing against any material (like concrete).

It can generate more force and even lift something off its foundation.

That is why concrete needs to be very thick and robust to support anything heavy, like a building or giant rock formations.

Does Foam Jack Last?

The answer is yes – but only for a short period. The foam will not regrow to its original thickness once it’s removed.

Foam comes in many grades (durometer). The general rule of thumb is that the higher the durometer rating, the stiffer and shorter-lived it is.

A high-grade 95 or 98 foam will be rigid initially but deteriorate quickly. Our experience with 98s shows approximately six months’ life span.

I have had no reported results from customers using a different grade of foam for this application other than stated above.

You should note that most do-it-yourself use either an 80 durometer or a custom formulated soft foam at their discretion.

This usually lasts a couple of years easily in this application.

Foam is excellent for this purpose because it does not break down any faster when exposed to the sun and elements.

If you want your jack to last longer than six months or concern yourself with UV exposure.

I recommend using an engineered resin system like Tufcoat Pro Resin instead of foam.

This will provide a more rigid, more resilient surface that’s much more UV resistant and give it a glossier finish which most people prefer.

Are Great Stuff Gaps and cracks waterproof?

Yes. Great Stuff, big gap filler insulation, is waterproof. Even no water will come out, even if you leave it for days after filling the gaps.

It’s important to note that Great Stuff is not a paintable solution. You can’t use it with water, then expect it to dry into a waterproof sealant using nothing else after you apply it.

Spray in some sealant afterward. Otherwise, the moisture will seep through over time and damage what’s behind or above your insulation.

I would recommend spraying one or two coats of KILZ primer over the top of it before applying any new coatings.

Spray foam sealants are also an option if someone wants to spend more money on something they don’t have to, but most people only need the primer for protection.

If you cannot afford to paint it, you should at least use two coats of primer.

Is Foam Jacking Better Than Mud Jacking?

Yes, it is. Foam jacking is an injection method used to lift a subsurface structure from the bottom surface by displacing or filling voids beneath it with injected foam.

The displacement of the void space reduces the load exerted on the structure and reduces the settlement.

You can apply it to both fine-grained soils and soft clays that have low permeability.

Here, excavation is not needed before using foam jacking, which saves time and money for developers who don’t need to reinforce an area before lifting it out of its subsidence trough.

It also performs better than mud jacking as there are no air pockets left behind after injecting.

Which allows for more effective compression on those sensitive areas such as parking areas, buildings, commercial property, and homes.

Foam jacking can lift larger structures such as roadways or pipelines with superior results.

When attempting to raise a small structure like a single residential home with mud jacking.

There will still be settlement after the injection process if the area is not reinforced first; thus, it will sink again over time, which leads to failed repairs.

You can also do foam jacking without having to pump water out of the ground, making it possible in drier climates where groundwater might not exist beneath newly filled grounds.

Not only is it known as a more efficient solution, but foam jacking is also more cost-effective than other methods.

It’s usually costs less than mud jacking, and you can rent the injection equipment instead of purchasing it.Since it doesn’t need excavation beforehand.

You don’t have to pay for the labor associated with that work which means you save money upfront on projects that are smaller or need to go fast.

And then there’s the factor of ongoing operating costs where mud jacking would need injecting liquids like bentonite.

These liquids could add up in terms of time and resources required compared to using compressed air to inflate the polyurethane mixture into the soil.

Foam jacking also benefits by being environmentally friendly as it doesn’t create any liquid runoff or need harmful chemicals for injection.

Is Slab Jacking Permanent?

Yes. Once you jack a slab, the foundation steel will not move back into place.

Slab jacking is fully driven by hydraulic pressure. Once it releases the pressure, the foundation steel will remain lifted.

The only way to “undo” slab jacking would be to jack the foundation back into position with increased pressure than what was initially used during the original lift.

There are other ways to repair a floor that has settled beyond slab jacking; one standard option would be mud jacking.

This process involves injecting an epoxy material under the concrete to raise it back up instead of using hydraulics like slab jacking.

Does Great Stuff Spray Foam Absorb Water?

(Imagine lifting a flagstone or piece of wood with your palm versus using a crowbar).

Mud jacking uses much less pressure than slab jacking and might be the preference in some situations.

Can I Spray Foam On A Wet Surface?

No. When spraying polyurethane, the key is to make sure the surface is dry before you start.

If it’s too late and your floor or wall has already become wet, you’ll need to wait until they’re dry again. You can also use a dehumidifier or fan to speed up the drying process.

Spray Foam Insulation is best used when done so in drier conditions with minimal humidity levels.

It will take longer for walls and floors to dry when using this insulation method because it takes time for the moisture trapped within them to evaporate through.


Spray foam insulation is a perfect solution for homes with any of these problems.

If you are looking for an easy to install, quick-drying, and cost-effective way to get your home or building insulated, then spray foam may be the right option for you.


Hi! I' am Tyron. I faced many questions from customers about different products, and there was hardly any help on the internet. After learning all the things about these products as a manager the hard way, I decided to start a blog and help other people.

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