Will Great Stuff foam lift concrete?

When it comes to DIY and home improvement projects, many homeowners find themselves wondering if Great Stuff expanding foam can be used to lift concrete that has settled or sunk over time. Great Stuff foam is a popular polyurethane-based insulating foam sealant made by Dow that is commonly used to fill gaps and cracks around windows, doors, pipes, and more. But can it also be used for the heavy duty task of concrete lifting? Let’s take a closer look at whether Great Stuff foam has what it takes to lift and level out concrete.

The Causes of Settled Concrete

Before we dive into whether Great Stuff foam can lift concrete, it’s helpful to understand what causes concrete to settle and become uneven in the first place. There are several common reasons concrete may sink or become unlevel over time:

• Normal settling – All concrete settles slightly as it cures and ages. Some settling is normal, though more than 1 inch over 20 feet is usually considered excessive.
• Poor initial pour – If the underlying soil wasn’t compacted properly before pouring, it can lead to future settling.
• Weak soil – Soft, sandy, or improperly compacted soil is more prone to settling under the weight of concrete.
• Erosion – Water erosion around or under the concrete slab can cause sinking.
• Heavy loads – Parking large vehicles like RVs or dump trucks on the slab can cause it to settle.
• Underground voids – Ants, rodents, or root systems creating voids under the concrete can lead to sinking.

These issues cause concrete to slowly sink unevenly, leaving dangerous trip hazards or problems with cracking and structural integrity. This is when homeowners start wondering about using Great Stuff foam as a quick fix.

Can Great Stuff Lift and Level Concrete?

Now that we know why concrete can settle and become uneven, let’s look at whether Great Stuff foam has the right properties and capabilities to lift and level concrete slabs:

Expanding Capability

One of the main selling points of Great Stuff foam is its ability to expand up to 30 times its original volume after being dispensed. This expansion capability allows it to readily fill gaps and create an airtight seal. However, there are limits to how much expandable foam can expand and the pressure it can exert.

While Great Stuff may feel quite solid and stiff after curing, it doesn’t have anywhere near the strength and weight bearing capacity of concrete. Concrete slabs are extremely heavy – a typical 4 inch thick slab can weigh over 100 pounds per square foot. Great Stuff foam simply doesn’t have the structural strength to lift and support that much weight.

Bonding Ability

For Great Stuff foam to lift concrete, it would need to bond very rigidly and hold things in place under tension. However, its bonding strength is meant more for filling gaps rather than structural adhesion. Typical Great Stuff foam usually only sticks to surfaces with a strength of around 14 psi.

By comparison, high strength construction adhesives can have tensile bond strengths of over 200 psi on concrete. So Great Stuff doesn’t have the bonding power needed to lift and permanently hold concrete in place against forces trying to make it settle.

Long Term Durability

Lifting concrete requires a very durable, long-lasting solution. However, Great Stuff foam is only designed for temporary, low-strength applications like sealing and insulating cracks and gaps. It’s not made to permanently support heavy structural loads.

When used in thin layers, Great Stuff foam tends to soften, compress, and lose strength over time – especially when exposed to weather. This means it could slowly give way and allow the concrete to re-settle if it was used to try lifting or leveling a slab.

Professional Concrete Lifting Methods

Since the properties of Great Stuff foam make it unsuitable for effectively lifting and leveling concrete, what methods do professionals use instead? Here are some of the most common and effective ways to lift settled concrete:

Mudjacking

Mudjacking involves drilling small holes in the sunken concrete and pumping a mud or slurry mix underneath to gently raise it back into place. The slurry mix hardens to permanently support and level the slab. Mudjacking can lift concrete up to 1.5 inches.

Slabjacking

Similar to mudjacking, slabjacking uses polyurethane expanding foam rather than a cement mix to fill voids and raise the concrete. Small holes are drilled and expanding foam is injected to slowly lift the slab. Slabjacking can lift concrete up to 3 inches.

Foam Injection

For more significant settling up to 7 inches, higher density polyurethane foams are injected under pressure through drilled holes to fill voids and lift the concrete. The foam expands and hardens to solidly support the slab.

Concrete Grinding

For minor sinking under 1 inch, concrete grinding uses planar machines to mechanically shave down high spots and level the slab. This is a temporary fix and doesn’t address underlying voids.

Concrete Replacement

In cases of extreme settling or sinkholes, sections of the concrete may need to be removed and repoured level with the rest of the slab. This is the most expensive fix but may be necessary with major soil and erosion issues.

Conclusion

While Great Stuff foam has many beneficial uses for sealing cracks and gaps, it simply doesn’t have the right properties and capabilities when it comes to permanently lifting and leveling sunken concrete slabs. It lacks the strength, durability, and bonding power to effectively raise concrete and keep it supported. Homeowners are better off utilizing professional methods like mudjacking, slabjacking, or foam injection to lift settled concrete.

Great Stuff Foam Applications

Even though it can’t lift concrete, Great Stuff foam is extremely versatile and useful for smaller home insulation and sealing jobs like:

• Filling gaps around windows, doors, pipes, vents, etc.
• Sealing air leaks to improve insulation
• Insulating rim joists in basements
• Soundproofing interior walls and floors
• Filling cavities around wiring, plumbing, ductwork
• Adhering insulation panels to walls and roofs
• Crafting decorative moldings and trims

It comes in several specialized formulas like fireblock, pestblock, land and pond, and more. Just don’t expect it to tackle heavy duty concrete lifting tasks.

Great Stuff Foam Types

Here is an overview of the main types of Great Stuff foam insulating sealants available:

Great Stuff Gaps & Cracks

– All purpose foam for interior cracks and gaps 1 inch or less

Great Stuff Window & Door

– Designed for sealing around windows and door frames

Great Stuff Fireblock

– Fire resistant formula for sealing penetrations and blocking fire spread

Great Stuff Pestblock

– Contains pesticides to block insects from entering through gaps

Great Stuff Big Gap Filler

– For filling larger gaps up to 3 inches wide

Great Stuff Pond & Stone

– Specially designed for use near water features and landscapes

Great Stuff Multipurpose Black

– Black colored foam ideal for exposed areas and UV resistance

Tips for Using Great Stuff Foam

When using Great Stuff foam for sealing and insulating projects around your home, keep these important usage tips in mind:

• Always read and follow the product safety guidelines.
• Wear gloves and eye protection when handling.
• Only use in well-ventilated areas and avoid breathing fumes.
• Dispense in beads rather than large globs for the best expansion and curing.
• Moisten surfaces slightly before application to improve adhesion.
• Allow several hours for full expansion and 24-48 hours for complete curing.
• Cut away excess cured foam with a serrated blade.
• Uncured foam can be cleaned away with acetone or nail polish remover.
• Avoid overfilling gaps since pressure can warp surfaces as foam expands.

Used properly, Great Stuff foam is a handy DIYer’s secret weapon. But for concrete lifting jobs, call in a lifting professional for reliable results.

Frequently Asked Questions

Can I use Great Stuff foam to raise a sunken concrete walkway?

No, Great Stuff expanding foam does not have the strength or durability to effectively raise and support the weight of sunken concrete walkways long-term. You’ll need professional methods like slabjacking or mudjacking.

Will Great Stuff foam lift my concrete garage floor that is sagging?

Unfortunately no, Great Stuff foam should not be used try lifting sagging or settled garage floors, as it cannot withstand the weight and downward pressure. Professional slab lifting techniques are recommended for permanently raising garage concrete.

Can I use Great Stuff foam to stabilize my shifting patio concrete blocks?

It’s not advisable, as Great Stuff foam does not have enough structural strength and bonding ability to permanently stabilize shifting concrete patio blocks. Proper underlying support and proper block installation is key to stabilizing concrete paver patios long-term.

How much weight can expanding Great Stuff foam hold up?

Great Stuff foam has very low density and structural strength compared to materials like concrete. It is only designed to seal cracks and gaps, not support significant weight. The foam may feel quite stiff, but it will compress and deform over time when holding any substantial weight.

Will Great Stuff foam adhere well to cracked concrete surfaces?

Yes, as long as the concrete surface is clean, dry, and properly prepared, Great Stuff insulating foam can bond very effectively to fill in cracks and gaps in concrete. Its expanding nature allows it conform to the irregular shape of cracks for a tight seal.