When you picture your cat happily hopping through a cat window insert, you probably imagine freedom, independence, and hours of feline fun. But let’s be honest—if you’re like most cat parents, one big concern comes to mind before hitting “buy”:

Do cat windows let in drafts?

It’s a fair question. No one wants their energy bill creeping up or cold air sneaking in every time their cat goes exploring. The truth is, poorly made pet doors can cause draft issues—but with the right design and setup, your home can stay just as cozy (and energy-efficient) as before.

In this guide, we’ll explain why drafts happen, how Cat Flap Fever prevents them, and 7 proven ways to keep your home warm in the winter, cool in the summer, and comfortable year-round.

Why Drafts Are a Common Concern with Cat Windows

Any time you add an opening to your home, the worry is the same: air escaping where it shouldn’t. With cat windows, drafts usually come from:

• Poor fit: A “one-size-fits-all” insert won’t match your unique window track, leaving gaps.

• Cheap materials: Thin plastic panels and flimsy flaps don’t insulate against temperature changes.

• Lack of weatherstripping: Without a seal, even tiny cracks can pull in chilly air.

• Wear and tear: Low-quality doors can warp or loosen over time, making gaps worse.

At Cat Flap Fever, we designed our custom cat window inserts to solve all of these problems. Each one is cut to your exact window size, made with durable PVC or Plexiglass, and reinforced with brush and foam weatherstripping to lock drafts out.

7 Ways to Keep Your Cat Window Cozy & Energy-Efficient

Here are seven proven ways to ensure your cat window insert adds joy—not drafts—to your home:

1. Choose a Custom-Fit Cat Window Insert

The biggest cause of drafts is a bad fit. Windows vary in track size, and a generic pet door won’t seal properly.

Cat Flap Fever inserts are custom cut to your exact window measurements. This snug fit eliminates gaps where air could slip through, keeping your home sealed tight against the elements.

Pro tip: If you’re unsure how to measure, we’ll guide you step-by-step—so your insert fits like a glove.

2. Pick the Right Material: Plexiglass vs. PVC

Not all materials perform equally when it comes to insulation.

• Plexiglass inserts give you visibility and a sleek finish, perfect for homeowners who want natural light.

• Solid PVC inserts offer extra insulation, making them ideal for harsher climates where temperatures swing dramatically.

Both materials are sturdy and weather-resistant, but picking the one that fits your environment makes a big difference in energy savings.

3. Seal with Foam Weatherstripping

Even the best-fitting insert benefits from an extra layer of insulation. Foam weatherstripping compresses against your window frame, blocking airflow and creating a thermal barrier.

Every Cat Flap Fever insert comes with foam weatherstripping around all four sides, so your cozy air stays in, and cold drafts stay out.

4. Add Brush Seals Around the Flap

The flap itself is another area where air can sneak through. That’s why we use brush weatherstripping around the swinging door.

This small but mighty feature:

• Stops air leaks

• Keeps bugs out

• Prevents rain and dust from sneaking in

It also softens the flap’s swing, which means less rattling on windy days.

5. Use the Locking Flap When Needed

Sometimes you want to completely shut the door—literally. Whether you’re away for the weekend, or it’s the middle of a snowstorm, our locking flap option lets you seal the cat door fully.

That means zero drafts, zero pests, and total peace of mind.

6. Pair with Seasonal Comfort Hacks

Even the most energy-efficient insert benefits from smart seasonal add-ons. Here are a few homeowner-approved tricks:

• Thermal curtains: Close them at night to lock in warmth.

• Draft stoppers: Use at the base of windows or doors for added insulation.

• Window film: An inexpensive way to add an extra layer of insulation in winter.

Combine these with your Cat Flap Fever insert, and you’ll keep your home snug all year.

7. Maintain & Refresh Your Weatherstripping

Over time, any seal can wear down from daily use. Luckily, foam and brush weatherstripping are easy to replace.

Check your insert once or twice a year:

• Is the foam still springy and tight?

• Are the brushes intact and covering the flap edges?

A quick refresh keeps your insert performing like new, season after season.

Seasonal Performance: Winter vs. Summer

A draft-free cat window isn’t just about staying warm in January—it’s about comfort year-round.

• In winter: Foam weatherstripping blocks icy gusts and keeps heat inside.

• In summer: The same insulation holds in cool air from your AC, so you’re not losing efficiency on hot days.

Think of it as giving your window an energy-efficient upgrade—with a built-in cat exit.

Why Draft-Free Cat Windows Matter Beyond Comfort

Sealing out drafts does more than make your living room cozy. It also:

• Lowers energy bills – Every gap means wasted heating or cooling.

• Improves indoor air quality – Drafts can bring in dust, pollen, and outside odors.

• Boosts home security – A tight-fitting, lockable insert keeps pests (and raccoons!) out.

With Cat Flap Fever, you don’t have to choose between comfort and convenience. You get both.

Cat Window Solutions for Renters

If you rent, you may be doubly concerned: will a pet door not only let in drafts but also cause permanent damage to your home?

That’s where Cat Flap Fever shines:

• No tools required

• No drilling, cutting, or permanent changes

• Easy to install and remove when you move out

You get a draft-free, energy-efficient solution—and keep your deposit safe.

Real Stories from Cozy Homes

Here’s what a few of our customers have said:

“Fit like a tight glove! No gaps at all. We installed in December and our house stayed warm—plus, the cat figured it out in two tries.”

“We live in the Midwest, so cold winters are no joke. I was worried about drafts, but this thing seals better than my actual windows!”

“My apartment is small, so I couldn’t afford to lose heat or AC. The weatherstripping really works, and I love that I didn’t have to drill or damage the window.”

Proof that comfort, efficiency, and feline freedom can go hand in hand.

Final Takeaway: Cozy Homes, Happy Cats

So, do cat windows let in drafts?

They can—if you buy a flimsy, one-size-fits-all model. But with Cat Flap Fever’s custom-fit inserts, weatherproof materials, and draft-blocking features, you don’t have to choose between keeping your cat happy and keeping your home cozy.

Give your cat freedom. Keep your home energy-efficient. And enjoy the best of both worlds—with zero drafts.

Ready to create a draft-free, pet-friendly home?
👉 Explore Cat Flap Fever’s custom cat window inserts today and see why cat parents across the U.S. are saying it’s the best upgrade they’ve ever made for their pets and their homes.