A pet door installed correctly is barely noticeable on your energy bill. Installed wrong, it’s an unsealed hole in your home’s insulation, and that matters here: Colorado Springs temperatures can swing from 14°F at 6am to 55°F by 2pm, so a poorly sealed pet door lets in drafts and cold air while your heat escapes right through it. I get called out on this more than you’d think, usually after someone’s installed one themselves and can’t figure out why the hallway near it never warms up. You’ll feel it every winter morning before your coffee is done. Here’s how I do it right, every time.
What’s the Energy Seal Problem With Pet Doors?
Your building envelope is the outer shell of your house that separates the heated inside from the cold outside (I think of it as the jacket your house is wearing, and every unsealed opening is a hole in that jacket). Every opening in it (windows, doors, outlets, and the holes where pipes and wires pass through) is a path for heated air to escape and cold air to get in. A pet door is a hole you cut on purpose. That means the seal on the door itself is your only line of defense.
Single-flap pet doors with no magnet are the worst offenders. The flap moves freely. In Colorado’s regular wind, that means it moves constantly: flapping open, letting cold air in, flapping closed, then opening again. On a January night at 6,035 feet, that adds up to real heat loss.
The cost adds up faster here than in milder places. Daily temperature swings top 40°F, and the heating season runs from about September through May. Over a season that long, the energy lost through a poorly sealed pet door keeps piling up.
What Type of Pet Door Should You Buy?
Dual-Flap with Magnetic Closure (Recommended Baseline)
This is the minimum I’ll install in a Colorado Springs climate, and I tell every client the same thing: don’t let anyone talk you into a single flap up here. Two flaps with an air gap between them, plus a magnet at the bottom of each flap. The air gap acts as insulation. The magnet holds each flap shut against the wind.
Look for: flexible vinyl or rubber flaps rated for low temperatures (some flaps stiffen and crack below 0°F), magnetic strips along the full perimeter of the flap (not just the bottom edge), and an adjustable-tension mounting frame.
Brands that hold up in cold climates: Endura Flap, PetSafe Extreme Weather, Hale Pet Doors.
Electronic/Microchip-Activated Door
The most airtight option. A hard panel covers the opening and only unlocks when your pet’s microchip or a collar sensor comes close. When your pet is inside, the panel is locked shut. Closed, it insulates about as well as the door around it, instead of relying on a flapping vinyl seal.
These run $200–$500 for the unit and require a power source (typically battery or AC adapter). The tradeoff: slower open/close cycle than a passive flap door, and a pet that needs to learn to wait for the door to cycle.
Good for: homes where energy efficiency is a priority, homes with security concerns about wildlife or neighborhood animals accessing through the pet door, and owners of cats or small dogs where the smaller opening size limits the wildlife intrusion risk.
Sliding Glass Door Insert
If you mainly reach the yard through a sliding glass door, a pet door insert is the simplest installation: no cutting, no framing, no changes to the structure. The insert replaces the glass panel or slides in alongside it.
The limitation: these reduce your light and can look bulky. They also reduce the usable opening of your sliding door. For renters or homeowners who want reversibility, they’re the right solution.
Where Should You Install a Pet Door?
In the door itself: The most common location and usually the cleanest. Works in wood, steel, and fiberglass doors, though steel and fiberglass take more care during cutting. Keep the pet door out of any glass part of the door (cutting into glass is not a DIY project, and I’ve been called in to fix more than one attempt at it).
In the wall: Needed when there is no door in a practical spot, or when you want to send the pet to a specific part of the yard. A wall install means cutting through the exterior siding, the sheathing (the panels under the siding), the framing (working around the studs), the insulation, and the drywall. You have to frame the opening, insulate the lined tunnel that runs through the wall, and add weathertight flashing on the outside. Flashing is the metal or plastic that channels water away from the seam so it can’t get into the wall. This is a legitimate contractor job, not a Saturday afternoon project.
In the garage wall, opening into a dog run: A popular setup in Colorado Springs, and honestly one of my favorite requests to get. The pet reaches a covered, fenced run from the garage instead of going straight into the yard. That solves the “letting the dog out at 2am in January” problem. Installation is simpler because exterior garage walls usually aren’t required to be insulated. You still want a quality flap door for draft control.
How Do You Install a Pet Door in a Door Panel?
Step 1: Measure your pet correctly. Width: measure your pet at the widest point (usually the shoulders or hips). Height: measure from the floor to the top of the back. Add about 2 inches to each for clearance. The bottom of the pet door (the part your pet steps over) should sit no higher than your pet’s lowest point, the bottom of the chest or belly. Lower is better. Set it low enough that they don’t have to jump, but high enough to clear the door sweep and weather stripping at the base of the door.
Step 2: Use the template. Every quality pet door kit includes a template. Tape it to the door in the correct position, confirm measurements from all edges, and mark your cut lines. Do not skip this step. A miscut on a steel or fiberglass door can’t be undone.
Step 3: Drill corner holes first. Drill a hole large enough for your jigsaw blade at each corner of the cut area. This gives you an entry point for the saw and creates a clean corner rather than an overcut.
Step 4: Cut. Wood doors: jigsaw with a fine-tooth wood blade. Steel doors: jigsaw with a metal-cutting blade, slow speed. Fiberglass doors: jigsaw with a fiberglass blade, slow speed, with a vacuum to capture the glass fiber dust. Wear a respirator.
Step 5: Smooth the edges and seal. A cut in a steel door leaves sharp metal burrs. File or sand them smooth (this is called deburring) so they don’t wear against the pet door frame. Steel and fiberglass doors have a foam insulation core. The cut exposes that foam, so seal it with spray foam or caulk before you install the frame.
Step 6: Install the frame. Most pet doors use a two-piece frame: an inside panel and an outside panel that bolt together through the door. Tightening them squeezes a foam gasket against both faces of the door for a seal. Follow the manufacturer’s instructions. Make it snug, but don’t overtighten on a thin door panel.
Step 7: Apply exterior caulk. Run a bead of exterior silicone caulk around the outside frame where it meets the door. This is the waterproofing step, and it’s the one I see skipped the most on DIY jobs. Colorado Springs sits at high altitude with strong sun, so uncaulked gaps break down the frame’s mounting faster here than in other places.
Maintenance
Inspect the flap seal annually. The flexible flap material stiffens and eventually cracks in cold weather, especially if it’s low-quality vinyl. Check in October before the first hard freeze (this is the one maintenance item I remind clients about every fall, because it’s so easy to forget until you’re already feeling the draft). A cracked flap doesn’t seal, which means it doesn’t insulate.
Clean the magnetic closure strips. Dirt and debris on the magnetic closure prevents the seal from engaging fully. Wipe them down seasonally.
Check the frame caulk. This caulk is on the outside of your house, so it takes the full freeze-thaw cycle (water seeps into a gap, freezes, expands, and pries it wider) plus strong sun. Inspect it every fall and recaulk any gaps that have opened.
Jonathan Shea is the owner of The Colorado Handyman, serving Colorado Springs and the Pikes Peak region. Flat-rate written estimates, no hourly billing surprises. Licensed and insured with $2M general liability coverage.
Get a free written estimate: Contact The Colorado Handyman or call (719) 243-9718.
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