Composite doors are a popular choice for UK homeowners thanks to their durability, security, and stylish appearance. Unlike traditional timber doors, composite doors combine multiple materials (uPVC, wood, insulating foam, and GRP skins) to provide excellent insulation and weather resistance. While it’s always recommended to hire a professional fitter, some experienced DIYers may want to understand the fitting process. Here’s a clear breakdown of how to fit a composite door.
Step 1: Prepare the Opening
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Remove the old door and frame carefully, ensuring no damage to the surrounding brickwork or plaster.
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Clean the opening thoroughly, removing debris, old sealant, or screws.
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Measure the aperture to confirm that your new composite door and frame will fit securely.
Step 2: Position the New Frame
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Place the new frame into the opening.
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Use spirit levels to check that the frame is plumb (vertical) and square.
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Packers or shims can be used to adjust the position until the frame sits perfectly.
Step 3: Secure the Frame
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Drill fixing holes through the frame sides (avoid drilling through the threshold or head).
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Insert frame fixings or screws securely into the surrounding brick or blockwork.
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Check alignment at every stage—tighten carefully without warping the frame.
Step 4: Install the Door
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Hang the fitted composite doors onto its hinges within the secured frame.
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Check that the door opens and closes smoothly without catching.
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Ensure even spacing (known as “margins”) around the edges for a neat fit.
Step 5: Fit the Hardware
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Attach handles, letter plates, knockers, and any other accessories.
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Install the locking system—most composite doors come with a multipoint locking mechanism.
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Test the lock thoroughly to ensure smooth operation and maximum security.
Step 6: Seal the Frame
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Apply a quality external sealant around the frame to prevent draughts and water ingress.
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Fill any small internal gaps with low-expansion foam or suitable filler.
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Smooth sealant edges for a professional finish.
Step 7: Final Checks
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Open and close the door multiple times to confirm alignment.
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Test the lock, handles, and weather seals.
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Clean the frame and glass for a polished look.
Why Professional Installation Matters
Although this guide shows the process, fitting a composite door requires precision tools and experience. An incorrectly fitted door can cause draughts, leaks, and security issues. Hiring a professional installer ensures your composite door lasts for decades, performs efficiently, and meets guarantee requirements.
