A pet door is a convenience that becomes a problem when it’s the wrong product or installed without attention to the energy seal. In Colorado Springs, where the temperature might be 14°F at 6am and 55°F by 2pm, a poorly sealed pet door is a source of drafts, heat loss, and cold infiltration that you’ll feel every winter morning before your coffee is done.
Done correctly, a pet door is nearly invisible on your energy bill. Here’s how to do it correctly.
The Energy Seal Problem
Every opening in your building envelope — windows, doors, outlets, penetrations — is a path for conditioned air out and unconditioned air in. A pet door is a deliberate opening, which means the seal quality of the door itself becomes your only line of defense.
Single-flap pet doors with no magnetic seal are the worst offenders. The flap moves freely, which means in Colorado’s regular wind, it’s moving constantly — flapping open, letting cold air draft in, flapping closed, opening again. On a January night at 6,035 feet, that’s a meaningful heat loss.
The Colorado-specific calculation is more aggressive than in other markets. With daily temperature swings exceeding 40°F and a heating season that runs effectively from September through May, the energy cost of a poorly sealed pet door compounds over a long heating season.
What to Buy
Dual-Flap with Magnetic Closure (Recommended Baseline)
Two flaps with an air gap between them, magnetic closure at the bottom of each flap. The air gap provides insulation value; the magnetic closure seals the flap against wind movement. This is the minimum worth installing in a Colorado Springs climate.
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 approaches. When your pet is inside, the panel is locked — which means it has the thermal performance of the surrounding door panel rather than 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 your primary yard access is through a sliding glass door, a pet door insert is the simplest installation — no cutting, no framing, no structural modification. 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 to Install It
In the door itself: The most common location and usually the cleanest. Works in wood, steel, and fiberglass doors, though steel and fiberglass require more care during cutting. Keep the pet door out of the glass portion of a door (if applicable) — cutting into glass is not a DIY project.
In the wall: Necessary when no door in a practical location exists, or when you want to direct the pet to a specific yard area. Wall installation requires cutting through exterior siding, sheathing, framing (avoiding studs), insulation, and drywall. Proper framing around the opening, insulating the sleeve through the wall, and weathertight flashing on the exterior are all required. This is a legitimate contractor job.
In the garage wall, accessing a dog run: A popular setup in Colorado Springs — the pet accesses a covered, fenced run from the garage rather than directly into the yard, which solves the “letting out at 2am in January” problem. Installation is simpler because garage walls typically don’t have insulation requirements, though you still want a quality flap door for draft control.
The Installation Process — Door Panel
Step 1: Measure your pet correctly. Width: measure your pet at the widest point (typically the shoulders or hips). Height: measure from floor to top of the back. Add 2 inches to each dimension for clearance. The sill of the pet door should be at elbow height for your pet — low enough that they don’t have to jump, high enough to clear the door sweep and weather stripping.
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: Deburr and seal. Steel door cuts need deburring to protect the pet door frame from abrasion. Steel and fiberglass door cores are filled with foam insulation — exposed foam needs to be sealed with spray foam or caulk before the frame is installed.
Step 6: Install the frame. Most pet doors use a two-piece sandwich frame — interior panel and exterior panel that bolt together through the door, compressing a foam gasket against both door surfaces. Install per the manufacturer’s instructions, snug but not overtightened on thin door panels.
Step 7: Apply exterior caulk. Run a bead of exterior silicone caulk around the exterior frame where it meets the door surface. This is the waterproofing step and is frequently skipped. At Colorado Springs UV levels, uncaulked gaps degrade the frame mounting faster than in other markets.
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. 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. With Colorado’s freeze-thaw cycle and UV degradation, exterior caulk around the frame needs inspection every fall. 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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