At Armored Insulation, we talk with homeowners every day who want to make the right choice between fiberglass batt and spray foam insulation. What they’re really asking is: how do I make sure my home stays energy-efficient, quiet, and comfortable without regrets down the line? They want insulation that works, lasts, and doesn’t bust the budget.
We’ve installed both fiberglass and spray foam across Kentucky homes and businesses, and we know how to match the solution to your specific needs. In this guide, we’re not here to sell you on one optionwe’re here to show you how to make the best decision for your space. Whether you’re renovating, building new, or just tired of sky-high energy bills, we’re giving you a real-world, honest look at both options so you can move forward with clarity.
By the end of this guide, you’ll know the key differences between fiberglass batt and spray foam, how each one performs in real-world conditions, and when one might make more sense over the other. We’ll break it down simply, directly, and from the perspective of experts who install insulation for a living.
Insulation isn’t just about R-values on a spec sheet. It’s about how your home feels every day whether that’s winter winds creeping through the walls or a second floor that can’t cool down in summer. The right insulation controls temperature, sound, and moisture. Let’s look at how fiberglass batt and spray foam stack up.
Spray foam forms an airtight barrier when applied, sealing every crack and seam. Fiberglass batt sits in the wall cavity, but it can’t stop airflow unless it’s installed with perfect precision and a separate air barrier.
In homes where air leakage is a known issue or where HVAC systems are overworking spray foam insulation often creates an immediate difference in comfort and efficiency. We’ve had clients call us days after an install saying their HVAC cycles less and rooms feel even.
Fiberglass batt insulation delivers good thermal resistance if it stays in place and dry. In reality, we often find compressed batts behind drywall, or gaps around electrical outlets and wiring weak points that let conditioned air escape.
Spray foam adheres directly to studs and sheathing, expanding to fill every crevice. It’s especially useful in cathedral ceilings, rim joists, and around ducts areas batt insulation struggles to fully cover.
The insulation you choose should fit not only your performance goals, but your project timeline, building type, and future plans.
Fiberglass batt is relatively fast to install and cost-effective upfront. It’s available in standard sizes that fit typical stud bays, and doesn’t require specialized equipment. For open wall cavities in new construction or remodels, it’s a practical choice if you’re working with experienced installers like our team who know how to avoid gaps and compression.
Spray foam requires more setup and curing time. We use professional-grade equipment to apply either open-cell or closed-cell foam, depending on the job. It’s not a DIY material—temperature, humidity, and ventilation all affect the application.
The benefit? Once in place, spray foam doesn’t shift, settle, or sag. It bonds directly to the framing and acts as both insulation and air barrier, streamlining the building envelope.
Insulation isn’t just an expense it’s an investment in energy savings, durability, and comfort. But budgets matter, and different situations call for different approaches.
Fiberglass batt has a lower initial cost and can be ideal for budget-conscious projects or code-minimum requirements. However, without tight air sealing, it may lead to higher heating and cooling costs over time.
Spray foam comes with a higher price tag upfront, but for homeowners planning to stay put, the long-term energy savings and moisture control often justify the cost. We’ve seen spray foam cut energy bills by 30–50% in homes with previously leaky envelopes.
Fiberglass can sag, shift, or be affected by pests and moisture. If it gets wet, it loses its effectiveness until completely dried and sometimes needs to be replaced.
Spray foam is more durable and doesn’t degrade as quickly over time. It resists water absorption, adds structural stability, and won’t attract pests. That makes it a strong candidate for areas with humidity or frequent weather swings.
Beyond energy and dollars, insulation affects your home’s air quality, noise levels, and overall comfort. These often-overlooked factors make a big difference day to day.
Fiberglass insulation is non-combustible and widely used, but it doesn’t resist moisture. If you have a basement, crawlspace, or anywhere prone to dampness, spray foam offers a better barrier against mold growth and air infiltration.
Spray foam also reduces pollen, dust, and allergens entering the home by sealing gaps and voids. Many of our clients with allergy concerns choose spray foam for this reason.
Open-cell spray foam excels at sound dampening. Whether it’s reducing traffic noise, TV bleed-through between rooms, or echo in an open-plan layout, it adds a layer of acoustic comfort.
Fiberglass batts do offer some soundproofing, but only when installed with acoustic-grade density and in proper layers. It’s most effective when combined with resilient channels or other sound control measures.
Older homes and renovation projects pose different challenges. Insulation needs to adapt to existing framing, wiring, and conditions.
For walls that can be opened up, either insulation type can work well. In attics or crawlspaces, fiberglass may be quicker and more affordable. For enclosed cavities where removal isn’t possible, injection foam or dense-pack cellulose may be alternatives we can explore.
We often recommend spray foam for inaccessible rim joists, knee walls, or areas with complex geometry. It molds around irregular surfaces and fills tight gaps that batts can’t reach.
Every home tells a different story. Sometimes budget, layout, or code drives the decision. Other times, it’s about how long the client plans to stay in the home or how sensitive they are to drafts or allergens.
That’s why we don’t take a one-size-fits-all approach. We look at each space, listen to the client’s priorities, and propose the option that makes the most sense—whether that’s a simple fiberglass batt install or a comprehensive spray foam envelope.
Choosing between fiberglass batt and spray foam doesn’t have to be confusing or stressful. With the right information and a team that knows how to match materials to homes, you can make a choice you’ll feel good about for years to come.
At Armored Insulation, we don’t push products we solve problems. Whether you need a fast, cost-effective solution or want a long-term upgrade with spray foam, we’re ready to help.
Fiberglass batt sits in the wall cavity and slows down heat transfer. Spray foam expands into gaps and acts as both insulation and air seal, delivering a tighter building envelope.
Spray foam typically delivers better energy efficiency by preventing air leakage, which is a major source of energy loss.
Yes, when installed correctly by trained professionals like Armored Insulation. Once cured, spray foam is inert and safe for indoor air quality.
Fiberglass batts can be installed DIY, but mistakes in fitting or sealing can hurt performance. Spray foam should always be installed by licensed professionals.
Open-cell spray foam offers excellent sound dampening. Fiberglass batt can help but is less effective in open areas.
Spray foam can last over 30 years with little degradation. Fiberglass batt may require replacement or repair sooner if it’s disturbed or gets wet.
Both can be used in retrofits. Spray foam is often better for sealing irregular or hard-to-reach areas in older structures.
Moisture reduces fiberglass performance and can lead to mold if not addressed. Spray foam resists moisture and is often used in basements and crawlspaces.
Yes. Properly installed insulation especially spray foam can significantly lower heating and cooling costs.
Start with a free consultation. We’ll assess your space, listen to your needs, and recommend what’s right for your home not just a generic answer.