A composite front door is a solid core faced with a moulded skin, usually glass reinforced plastic, in a frame of its own. It is the default replacement for a timber or UPVC front door in Britain because it is dimensionally stable, secure and needs very little maintenance. It is not faultless, and the faults are predictable.
The problems that actually occur
Colour fade on a south facing door, particularly on dark reds and blues, is the most common complaint. Expansion and slight bowing on a dark door in strong sun is real and usually recovers as it cools, though it can make the door bind at the top on a hot afternoon. Beyond that, most reported problems are the hardware rather than the slab: multipoint locks going out of adjustment, hinges dropping, and the weatherseal flattening. Those are adjustments and parts, not a new door.
Can you paint composite doors?
Yes, with the right preparation and the right product, and no, not casually. The skin is a GRP surface with a factory finish, so it needs degreasing, a light key and a primer made for plastics, then an exterior paint suited to the substrate. Done properly it lasts; done with ordinary gloss over an unprepared surface it peels within a season. Check the guarantee first, because painting a door may affect it.
Composite door cost fitted: what the price includes
The door slab, the frame, the threshold, the hardware set, the glass unit if there is one, removal of the old door, fitting and making good, and the certificate. Sidelights and top lights add. The cheapest quotes usually differ on the lock and the hinge quality rather than the door, which is exactly where it matters. Ask what lock cylinder is fitted and whether it meets the recognised anti snap standard.
Security and the regulations
A front door on a new dwelling has a security requirement under Approved Document Q, and while replacing a door on an existing house is not usually caught by it, the same standards are the sensible specification. Ask whether the doorset is certified to a recognised security standard as a whole unit rather than relying on a lock brand, because the test is of the door, frame and hardware together.
Questions people ask about problems with composite doors
Do composite doors fade?
Dark colours on a sunny elevation can fade noticeably over years. Manufacturers differ, and the guarantee wording on colour is worth reading before choosing anthracite for a south facing door.
Why does my composite door stick in hot weather?
Thermal expansion of a dark slab in direct sun, usually binding at the top. It generally recovers as the door cools. Persistent binding is a hinge adjustment.
Can a composite door be repainted a different colour?
Yes with a plastics primer and a suitable exterior finish after proper preparation. Check whether it voids the manufacturer's guarantee first.
Are composite doors more secure than UPVC?
The slab is more resistant to physical attack, and in practice the lock cylinder and the frame fixing decide most break ins. Specify a certified doorset and an anti snap cylinder whichever material you choose.