Can you put a cat flap in a composite door? Learn how to fit a cat flap in a composite door without damaging insulation, security, or performance.
What You’ll Learn
- Can you put a cat flap in a composite door safely?
- How to fit a cat flap in a composite door without damaging the structure
- How to choose the best cat flap for a composite door
- How much it costs to fit a cat flap in a composite door
(Estimated Reading Time: 5-6 Minutes)
Introduction
Got a cat that runs the house and a brand-new composite door you’re proud of? We get it. Composite doors are a go-to for UK homeowners thanks to their strength, security, and sleek design—but what happens when your feline friend wants their own private entrance?
Can you put a cat flap in a composite door? And just as important, how do you fit a cat flap in a composite door without damaging it or voiding the warranty?
The good news: you absolutely can—you just need to do it the right way.
In this guide, we’ll walk you through your options, from factory-prepped cat flap routing to expert post-install fitting (which we offer!). Whether you’re ordering a new door or updating an old one, we’ll help you create a solution that keeps your cat happy and your door looking (and performing) its best.
How to Fit a Cat Flap in a Composite Door: Your Options
Yes—but only if it’s done properly.
Composite doors aren’t built like timber or uPVC. They’re made with a solid timber or insulated foam core, encased in a durable GRP (glass-reinforced plastic) skin. This layered construction is what gives composite doors their strength and energy efficiency—but it also means they require extra care when cutting into.
If you put a cat flap in a composite door without proper planning or tools, you risk weakening the structure, causing leaks or draughts, or even voiding the warranty.
To keep your door performing as it should, we recommend one of two safe options:
- Choose a factory-routed cat flap when ordering a new door
- Hire a professional for a post-installation retrofit using the correct tools and seals
“We installed a SureFlap in our Comp Door rear door—no draughts, no damage, just a very happy cat.” — GFD Customer, Newcastle
Option 1: Factory Routing by Manufacturer (Solidor & Comp Door)
Ordering a composite door with cat flap routing? It’s the cleanest, safest, and most hassle-free option.
Both Solidor and Comp Door offer cat flap routing at the manufacturing stage—ideal if you want the flap built into the design from day one. A cut-out is precision-made in the lower solid panel during production, so your fitter won’t need to drill into the finished door.
You’ll need to supply your own cat flap (square or rectangular only) and provide a template before manufacture. Once installed, the flap fits straight into the pre-cut opening—no extra drilling, no mess, no damage.
This method keeps your door’s structure, insulation, and security features fully intact.
In fact if you select our installation service when purchasing your new composite door our friendly installers will install this for you on site.
Note: Factory routing is only available on solid lower panels, not glazed sections.
Option 2: Retrofitting After Installation (By a Professional)
Already have your door fitted? You can still add a cat flap for composite door setups—just don’t go DIY.
A qualified door fitter or glazier can retrofit a flap into the lower solid section safely. Just make sure they:
- Use a reinforced backing plate or sealant collar
- Avoid cutting through weather seals or structural layers
- Preserve thermal efficiency and internal insulation
DIY jobs on composite doors often go wrong—leading to draughts, cracked skins, or even voided warranties. Leave it to the pros.
“Don’t let YouTube convince you it’s an easy job. Composite doors need expert handling when it comes to modifications.”
Choosing the Best Cat Flap for a Composite Door
Not all cat flaps are made the same—especially when you’re dealing with a solid composite door.
For the best results, choose a cat flap for composite door installations that’s built to handle tough, rigid panels without causing damage.
Look for models with:
- ✅ Microchip access (e.g. SureFlap, PetSafe)
- ✅ Lockable settings for added security
- ✅ Draught-proof brushes or rubber seals
- ✅ Rigid frame to prevent flexing or cracking
Avoid ultra-lightweight models designed for uPVC—they’re too flimsy for composite materials and can lead to issues over time.
Cost of Fitting a Cat Flap in a Composite Door
Here’s what to budget depending on your approach:
| Option | Estimated Price |
|---|---|
| Factory-fitted (new door) | ~£50 extra |
| Professional retrofit | £120–£250 |
| Premium microchip cat flap | £50–£150 |
It’s usually cheaper and cleaner to go with factory fitting when ordering a new door. But if you already have a composite rear door, retrofitting is still totally doable.
Design Your Composite Door with Add-ons
Conclusion
So yes, the answer to “can you put a cat flap in a composite door” is a definite yes—just make sure it’s done properly. And now that you know how to fit a cat flap in a composite door the right way, you don’t need to choose between a secure, stylish entrance and your pet’s freedom.
Whether you opt for factory routing during manufacture or choose a professional retrofit, your composite door can stay draught-free, energy-efficient, and structurally sound.
Just steer clear of DIY shortcuts—composite doors are too valuable to risk with the wrong tools.
At GFD Homes, we offer high-quality composite doors from trusted brands like Solidor and Comp Door, both of which support cat flap compatibility. From front entrances to rear doors, we’re here to help you create a home that works for the whole family—tail and all.
🛒 Browse the full collection at www.gfdhomes.co.uk.
📞 Or call 01642 309576 for expert guidance and a no-pressure quote.
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Browse our articles for tips on choosing and customising your composite and rear doors
- Why Composite Rear Doors Are the Smartest Choice for UK Homes
- Back Doors: The Best Options for UK Homes
- Best Composite Doors in the UK: Top Picks for Style, Security & Value
- Trade Composite Doors: looking for trade prices? Visit our trade site, The Trade Village
FAQs: Can You Put a Cat Flap in a Composite Door?
Q: Will fitting a cat flap void my warranty?
Not if it’s factory-fitted or installed by a professional with approved parts.
Q: Can I install it into a glazed section?
No, not without specialist glass. It’s best to use a solid panel section.
Q: Will it affect insulation?
Minimal—especially if you use a flap with a draught seal and it’s properly installed.
Q: Can I add a flap after installation?
Yes—but it’ll cost more and require a trusted tradesperson. If you’re still shopping, consider adding it from the start.
Q: Can you put a cat flap in a composite door without affecting insulation or strength?
Yes — if done properly.
