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Great Stuff Pestblock VS Gaps And Cracks

Dupont’s Great Stuff Insulating Foam Sealant helps to fill gaps in both commercial and residential buildings. The manufacturer offers a variety of products designed for specific applications.

Let’s take a closer look at the Great Stuff Pestblock VS Gaps And Cracks products to determine similarities, differences, and when you should use one product or the other.

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08/13/2022 01:07 pm GMT
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08/13/2022 11:02 am GMT

What Are Insulating Foam Sealants?

Each of the products we are looking at is considered an insulating foam sealant. Two of the ingredients in each formula are the organic compounds isocyanate and polyol resin.

When mixed, the interaction causes the liquids to expand. This expansion is what allows the foam to fill open spaces.

Thermal Resistence To Heat Flow

Once the liquid hardens into a foam, these sealants provide insulation. The hardened foams created with both Great Stuff Gaps And Cracks and Great Stuff Pestblock help block:

  • Conductive Heat Transfer – The molecular bonds in the sealant is loose, resulting in a reduction of heat transfer
  • Convective Heat Transfer – Creating a seal that air cannot move through prevents external air penetration and internal air from escaping
  • Radiant Heat Transfer – The opaque characteristic of the foam does not promote the radiation of heat through this medium

Can Be Used Indoors And Outside

Dupont’s line of Insulating Foam Sealants is usable throughout your home. The products will maintain their color on inside surfaces. Exposure to the sun’s UV light can discolor the skin of both products. You can paint Gaps And Cracks or Pestblock to avoid UV damage.

The foam resists weather damage, which is another consideration for exterior surfaces.

What Surfaces Will They Adhere To?

Both sealants adhere to a variety of surfaces that include:

  • Glass
  • Masonry
  • (Most) Metals
  • (Most) Plastics
  • Wood

A porous surface is ideal. For metals and plastics, you can test a small section ahead of time to verify the sealant’s ability to adhere.

Suggested Applications

Dupont indicates that both products are for similar application areas. DIY projects include your home’s ductwork. That includes areas where HVAC penetrates ceilings, floors, and walls.

Penetration points for electrical work or plumbing is another area these sealants work well at. Both penetration points create space for air transfer and pest movement. These products fill the voids around conduits and pipes.

Another problem point that Great Stuff Gaps And Cracks and Great Stuff Pestblock are ideal for use are points of penetration in your attic. HVAC, wire ports, and roof vents have small spaces that the sealants can penetrate.

Dupont also suggests that these products work on rim plates and sill joists in your home as well.

Working With Great Stuff Insulating Foam Sealant

Dupont tests the entire product line in similar conditions to compare the results. Gaps And Cracks, as well as Pestblock, lose tack after 5 – 15 minutes. You can trim them after an hour, and the sealants will cure after one day.

The foam can be cut or sanded to shape. Both products will accept paint or stains.

These sealants expand up to one inch before hardening. That makes them ideal for the applications written about previously. They are not the best foam sealants to use on large voids, though.

Great Stuff Pestblock VS Gaps And Cracks


Dupont’s Great Stuff Gaps And Cracks come in creme color. The Great Stuff Pestblock is grey.

These colors are used as an identifier and do not change the foam’s composition. You may find that one color works better for your project area, but keep in mind that you can paint or stain either sealant.

Container Size

You will get 20 ounces of Gaps And Cracks in each canister. Pestblock sells in a smaller 12-ounce can. The larger container offers more product to use, with the smaller can only providing you with easier storage.


Dupont supplies a standard straw dispenser with the Great Stuff Gaps And Cracks.

Great Stuff Pestblock includes the Smart Dispenser. The design uses integrated components that address issues found with straw applicators. These improve:

  • Drips – A new trigger design stops flow immediately upon release
  • Precision – The tapered tip creates a smaller bead of foam
  • Reuse – The assembly allows you to reuse the product for 30 days


You will pay about twice as much for Gaps And Cracks then for Pestblock. That means you will pay less for an ounce of Pestblock and could factor for larger jobs.

At A Glance

Dupont’s Great Stuff Gaps And Cracks

This product improves energy efficiency in your home by reducing unwanted airflow.


  • Larger cannister
  • Better with moisture
  • Color easier to paint or stain


  • Cost more
  • Standard straw dispenser

Dupont’s Great Stuff Pestblock

This product eliminates pest problems without using pesticides.


  • Not harmful to bees
  • Penetrates small cracks easily
  • Reusable for up to 30-days


  • Smaller canister
  • Grey is harder to cover with paint or stains
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