Cellulose vs. Fiberglass: Which Insulation Performs Better in North Texas Heat?
If you’ve lived in DFW for more than five minutes, you know: the heat here is different. And that heat loves to camp out in your attic—pushing temperatures to 130–150°F in July and August. That’s why insulation choice matters more here than in most parts of the country.
Fiberglass blown-in insulation is extremely common, but in real-world North Texas conditions, cellulose often performs better. Here’s why:
Cellulose Is Denser — and Density Matters in Texas Heat
Fiberglass blown-in insulation is light and airy. Great for quick installs, but not so great when your attic becomes a convection oven.
Cellulose is much denser, which means it allows less air movement, slows down heat transfer, and helps stabilize indoor temperatures. In DFW’s brutal summers, density equals performance.
Cellulose Fills Gaps More Completely Than Blown Fiberglass
Both products are blown-in, but they behave differently once installed.
Fiberglass blown-in insulation can leave small voids around wiring, framing, and tight corners. It can also form air channels where heat can move more easily, and it may become uneven if disturbed by airflow.
Cellulose, because of its smaller particles and higher density, naturally settles into cracks, crevices, and irregular spaces. It fills around obstructions better and creates a more consistent thermal blanket - exactly what you want in a hot climate.
Cellulose Performs Better During Extreme Heat
Fiberglass loses performance as attic temperatures rise because heat passes through the air pockets more easily. That’s not ideal when your attic is hotter than your grill.
Cellulose handles high temperatures better because it slows air movement, resists radiant heat gain more effectively, and reduces the “radiant oven” effect that pushes heat into your living space. This gives your AC a break - especially in peak summer.
Bonus: Cellulose Helps Reduce Noise
Because cellulose is denser, it also provides better sound control. It helps reduce outside noise, HVAC sounds, and general home echoes. Not the main goal, but a nice improvement.
Most DFW Attics Need More Than Just New Insulation
Insulation alone isn’t the finish line. Before adding new material, many attics in North Texas need attention underneath the surface.
Common issues include:
Air leaks around plumbing, wiring, and framing
Missing or crushed baffles
Ventilation imbalances
Compacted or contaminated old insulation
Rodent tunnels
Dust and debris buildup
That’s why JayCo Insulation performs a complete attic restoration before adding cellulose.
Our Attic Restoration Process Includes:
Full insulation removal
Attic sanitization
Air sealing
Baffle installation
High-density cellulose blown in to the proper depth
Your insulation only performs its best when the entire attic environment is corrected.
Final Thoughts
Fiberglass blown-in insulation isn’t “bad” - it’s just not the top performer in our extreme Texas heat. If you want more consistent comfort in both summer and winter, cellulose gives you a noticeable advantage.
JayCo Insulation offers free attic assessments across DFW if you want to see what’s happening above your ceiling.