Key Takeaways
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Whether you’re looking to increase your home’s energy efficiency, stop moisture problems in their tracks, or just make your home more comfortable, insulating your basement is key. It saves energy and helps keep a comfortable temperature in your home all summer and winter long.
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Expanded Polystyrene (EPS) and Extruded Polystyrene (XPS) are the most commonly used rigid foam insulations. Both have unique properties that make them suitable for different needs, but it’s essential to know the difference between the two before making a selection.
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Of them all, EPS is the most cost-effective and eco-friendly, as well as providing a good level of moisture resistance. It potentially has a lower R-value and compressive strength than XPS.
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With the added R-value and compressive strength, XPS is best suited for areas that need added durability or impact resistance. It is less environmentally friendly and more costly than EPS.
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Proper preparation of basement walls and following installation best practices is key for both EPS and XPS. This helps achieve optimal performance and prevents future problems such as moisture accumulation.
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Whichever type of basement insulation you choose to install, always keep the long-term in mind. Look out for insulation thickness, resistance to mold, and compatibility with other materials. These factors are key in determining durability and effectiveness.
Insulating a basement properly requires knowing the insulation materials insulation values, moisture resistance, and installation requirements.
Made from expanded polystyrene (EPS), Insulfoam is economical and versatile. Conversely, extruded polystyrene (XPS) provides greater compressive strength and superior moisture retention.
Both are great alternatives, depending on your project’s priorities and budget. Selecting the best material increases energy efficiency and durability for basement environments.
This decision is an important move in your home improvement project.
Understanding Basement Insulation
What is Basement Insulation
Basement insulation is the key to saving your basement and your indoor comfort. It’s an impressive slab of energy efficiency and moisture problem prevention, but only when applied to the walls and floors of below-ground spaces.
Basements are unique in that they are in direct contact with the surrounding soil. This genetic link usually renders them some of the worst insulators in a house. At 20 percent moisture content, soil provides an R-value of only 0.25–1 per inch, meaning it does little to slow heat transfer.
Without proper insulation, basements easily turn into cold, drab, energy-wasting holes in the ground—draining home comfort and driving up energy bills. Insulating your basement helps eliminate these issues by providing a layer of insulation that greatly resists heat from escaping.
It stops moisture condensation, creating a drier, more pleasant and usable living area. For those planning renovations or seeking to finish an unused basement, selecting the right insulation material can make all the difference in both performance and long-term satisfaction.
Why Insulation is Important for Basements
Insulating a basement has wider implications than simply making the basement warmer in winter and cooler in summer. Heat can never flow from a cooler place to a warmer place – that would be a miracle!
In an uninsulated basement, this process lets warmth seep from your living areas down into the earth. Proper insulation reduces this heat loss, making it more affordable to heat homes during Canada’s long and cold winters.
Moisture control is the second most important reason for basement insulation. Basements are especially susceptible to moisture because they’re located below grade. Without insulation, moisture can continue to infiltrate.
This can lead to issues including mold growth, structural damage, and an unpleasant musty ambiance. Rigid foam insulation is one of the best materials to use, and it acts as your barrier. They lower the chances of moisture penetration and contribute to a healthier indoor environment.
Basement insulation is an intelligent long-term investment. Improving your home comfort by finishing your basement increases your property value, making the space a usable space.
Sustainable building practices are catching on. Homeowners should be welcoming insulation solutions like these that help the U.S. Reach its carbon-neutral goals by 2030 and well into the future.
Common Types of Rigid Foam Insulation
Basements are another great use for rigid foam insulation, specifically due to its durability and moisture resistance. It offers great R-values as well, which adds to its energy-efficient appeal.
The other two commonly used options are Extruded Polystyrene (XPS) and Expanded Polystyrene (EPS), like Insulfoam. XPS is a strong, closed-cell foam that is widely recognized for its compressive strength and resistance to water.
It is most commonly installed in roofing applications and costs about $0.70/sf. One major disadvantage of XPS is its harm to the environment. The toxic emissions released during the manufacturing process are just the start.
Over time, XPS can absorb moisture, causing its R-value to plummet. This makes it a great insulator when first installed, but its insulating performance can diminish after decades of exposure.
Of all insulation products, Insulfoam EPS is one of the most environmentally friendly. It’s got a deep bench, with a track record exceeding 50 years. It’s more lightweight and cost-effective, and keeps its R-value over time better than other options—even in moisture-rich settings like basements.
As green building continues to become more prevalent, Insulfoam is the clear choice. It’s a practical and impactful way to shrink carbon footprints without sacrificing insulation performance.
In fact, building professionals would more commonly recommend EPS for basement projects in Zone 5 climates, where it outcompetes other materials by leaps and bounds. Its versatility and affordability make it a practical solution.
With some good advice, homeowners can thoroughly insulate their basements without spending a fortune.
Comparing EPS and XPS Insulation
1. What is EPS Insulation
Expanded polystyrene is a lightweight, rigid foam insulation widely used in commercial and residential construction. It’s often made by expanding small polystyrene beads and then fusing them together to form a solid sheet. EPS is more versatile, performing better than XPS in applications such as basement walls, under-slab insulation, and exterior sheathing.
EPS provides a high level of thermal resistance, making it big on insulation. It’s lightweight and easy to cut and shape, allowing it to be easily adaptable for different project needs. EPS is well-known for being cost-effective and readily available.
It’s easy to see why homeowners adore it for highly efficient insulation that won’t cost a fortune.
2. What is XPS Insulation
Extruded Polystyrene (XPS) insulation is a second type of rigid foam insulation. XPS is produced by extruding polystyrene plastic, forming a closed-cell structure that yields a denser, stronger insulation board. This process produces XPS’ characteristic smooth surface and superior resistance to water absorption compared to EPS.
XPS is often used in applications requiring greater durability like foundations, below-grade walls, and roofing systems. Its durability and moisture resistance make it a great choice where demand is at its most challenging.
3. R-Value Differences Between EPS and XPS
The R-value is a measure of an insulation material’s ability to resist heat flow. XPS usually has a higher R-value, often R-5 per inch. In comparison, EPS offers an R-value of R-3.6 to R-4.2 per inch.
This means XPS insulation offers superior thermal performance per inch thickness. EPS offers superior insulation performance, particularly when installed in thicker sheets. This combined with its typical cost-effectiveness makes it an excellent option for projects where thickness is not a concern.
4. Moisture Resistance Properties
XPS has superior performance in moisture resistance mainly because its closed-cell structure stops water absorption. This high moisture resistance quality allows XPS to be used in below-grade applications or areas that are susceptible to moisture exposure.
While EPS is not impermeable, it performs excellently under less demanding conditions. Even more protection is afforded by applying water-resistant coatings or membranes. Properly understood, installed, and detailed, installation techniques can make EPS even more resistant to moisture.
5. Compressive Strength Comparison
Where XPS really shines is in compressive strength, which usually ranges from 20 to 60 psi, per the product. This makes it the best choice for any heavy-load bearing applications, such as under concrete slabs.
EPS, on the other hand, can provide a compressive strength of 10-20 psi, which is sufficient for more lightweight applications. In short, for the majority of residential projects, you can choose either material and satisfy structural requirements.
If you require higher load resistance, XPS is the clear winner.
6. Cost-Effectiveness of EPS and XPS
Since EPS is typically less expensive than XPS, that can add up big time for projects on a budget. XPS insulations, on the other hand, excel in areas such as moisture resistance and compressive strength.
EPS still offers good insulating value at a lower cost. Insulating a basement wall with EPS can reduce material costs by hundreds of dollars. This strategy preserves excellent energy performance, even in areas that are more vulnerable to moisture concerns.
7. Environmental Impact Considerations
EPS definitely has the advantage in terms of sustainability. It has less impact on the environment due to fewer resources being used during production and the ability to be recyclable.
XPS, as durable as it is, is produced with blowing agents with higher GWP, thus not as environmentally friendly on the whole. For homeowners looking to prioritize sustainability, EPS offers a more environmentally friendly option.
Advantages and Disadvantages of EPS and XPS
Benefits of using EPS in basements
EPS remains the best value among all basement insulation solutions. It makes a great alternative for homeowners who want top-tier performance without top-tier cost. Available in pieces priced between $9 and $13, EPS is an economical choice that easily incorporates into a majority of renovation budgets.
Due to its lightweight and easy-to-cut nature, this helps speed up labor time and effort during basement work since it’s easy to handle and install. Its permeability to water vapor is another major advantage, with a perm rating as high as 5.0. This trait permits a bit of vapor diffusion, which is beneficial in the case of basements, where moisture management is critical.
If you are concerned about using green materials, EPS is the winner. It does not need to be virgin material, it often has recycled content and is reusable in other projects.
Drawbacks of using EPS in basements
EPS does have downsides. Its R-value, the industry standard measure of thermal resistance, is the lowest of all rigid foam insulations. Providing R-values ranging from 3.6 to 4.2 per inch, this rigid foam board provides quality thermal insulation. It’s not all it could be — at least when measured against other types.
This can result in the need for thicker panels to meet energy efficiency needs, which can limit usable space in confined spaces. EPS is permeable to some extent to water vapor. When done properly, this is a great practice, but it can cause issues in basements that are usually under high humidity.
If it is exposed to moisture over time, performance can be marginally affected. Its lower density structure ironically renders it more vulnerable to physical damage during installation or regular use.
Benefits of using XPS in basements
Extruded Polystyrene (XPS) is an even better, more durable, option for basement insulation. With an average R-value of 5.9 per inch, XPS offers the highest overall thermal insulation, making it easier for homeowners to create an energy-efficient building envelope.
Its closed-cell structure and smooth surface make it very resistant to moisture absorption. When exposed to continuous or intermittent wet conditions, it takes on less than 1% of its volume in water. Similar to EPS, XPS has very low permeability, with a perm rating of less than 1 for a 1-inch-thick panel.
This in turn makes it a superb barrier against water vapor. This quality is especially advantageous when used in basements, where moisture management is necessary to avoid mold and moisture issues. It’s a very dense, robust material. It tackles the dual challenges of installation and long-term use without sacrificing performance.
Drawbacks of using XPS in basements
Though strong, XPS does have some concerning weaknesses. One major drawback in comparison to EPS is cost, which is typically higher than that of EPS. This pricing out budget-minded homeowners.
XPS is highly non-fire-resistant, failing the NFPA 285 fire test for wall assemblies with steel studs. This limitation sometimes necessitates extra fireproofing during installation, adding to overall costs. The material’s low permeability is often touted as an advantage.
In some applications, it may trap moisture, making good design and ventilation critical. While XPS is durable, it is less environmentally friendly than EPS. It’s less recyclable and generally needs more energy in the production process.
