TL;DR
- Wipe the slab and frame with warm, soapy water and a microfibre cloth every six to eight weeks. Clean glass separately. That is the bulk of the routine.
- Avoid bleach, solvents, abrasive scourers, pressure washers, and WD-40 on the cylinder. Use silicone spray on hinges and graphite powder in the lock barrel once a year.
- Check the compression seals each spring and autumn using the paper test. Failed seal sections are inexpensive and quick to replace before they cause draughts.
- Sticking doors and stiff locks usually mean the slab has dropped on its hinges. Adjust the alignment rather than forcing the mechanism, and call the installer for persistent issues.
One of the genuine pleasures of owning a quality composite front door is that it asks very little of you. The GRP skin holds its colour for decades, the seals stay supple for years, and the lock mechanism continues to throw cleanly long after the rest of the house has needed a coat of paint. This is one of the reasons composite has become the dominant front door choice for UK homes in 2026: a 25 to 30-year service life with minimal fuss is genuinely on offer.
The catch is the word “minimal”. Minimal is not the same as none. A composite door that is never cleaned, never lubricated, and never inspected will quietly age faster than one that gets a few small habits applied to it across the year. The maintenance involved is genuinely modest: an hour or two per year, no specialist tools, no unusual products. This guide walks through exactly what to do, what to avoid, and how to spot when something needs an installer rather than a cloth.
If your current door is becoming difficult to clean, no longer seals properly, or is starting to affect your home’s kerb appeal, it may be worth exploring modern replacement door options for your home. A well-fitted new door can improve security, weather resistance, and thermal performance, while reducing the amount of upkeep needed over time.
Quick answer: the safest routine
For most UK homeowners, the right composite door routine is straightforward. Wipe the slab and frame down with warm soapy water and a microfibre cloth every month or two. Clean the glass separately with a standard glass cleaner. Lubricate the hinges and lock mechanism once a year with a silicone spray. Check the weather seals each spring and autumn. That is genuinely the bulk of it.
What you should avoid is also short. No bleach, no solvent cleaners, no abrasive scouring pads, no pressure washers and no oil-based lubricants on the lock cylinder. These are the products and habits that cause damage on composite doors, and the damage is usually irreversible.
The rest of this guide is the detail behind these basics: why each step matters, how to spot problems before they become expensive, and when to call your installer rather than reach for a cloth.
Why composite doors still need maintenance
Modern composite doors are remarkably low-maintenance, but they are not maintenance-free. The slab is engineered to weather decades of British rain and sun without warping, swelling or fading meaningfully, and a quality GRP skin holds colour better than almost any factory-applied finish on the market. So far, so reassuring.
Where attention pays back is in the moving parts and the seals. The hinges, multipoint lock, cylinder, letterplate restrictor and weather seals all benefit from light, regular care. Neglected, these are the components that fail first on otherwise sound doors. They are also the components that feel like the door itself failing, even when the slab is in perfect condition.
The other reason for routine inspection is that small problems are cheap to fix and big problems are not. A failing seal caught early is a £20 part. The same seal left to deteriorate causes draughts, condensation and water ingress that can damage the surrounding plaster and timber. A hinge that has dropped slightly is a five-minute adjustment. The same hinge left to drag the slab against the frame for a year wears the seal and stresses the lock.
What composite doors are made from and why that affects cleaning
Understanding what you are cleaning helps you avoid damaging it. A modern composite door is built from several layers, each with different properties.
The outer skin is glass-reinforced plastic (GRP), typically 2 to 3mm thick. It is moulded with a textured finish that mimics timber grain, then bonded to the structural core under pressure. The skin is what takes the weather, holds the colour, and gives the door its appearance. It is durable but not invincible: solvents, abrasives and harsh chemicals can dull or damage it permanently.
The core is the structural heart of the slab. Quality composite doors use either a solid timber core, a polyurethane foam core, or a hybrid of the two. The core is sealed inside the door and you should never see or touch it directly. If you can, the slab has been compromised and needs professional attention.
The frame is usually uPVC with steel reinforcement, although aluminium and timber frames are available on premium products. The frame profile is hollow with reinforcement at the locking and hinging points. It cleans much like the slab itself.
The glazing units, where present, are double-glazed with low-emissivity coatings and warm-edge spacer bars. They should be laminated rather than only toughened for security on a front door. Glass needs different care to GRP, which is why the cleaning routine separates the two.
The hardware (hinges, lock, cylinder, handle, letterplate, knocker, spy hole) varies in finish but generally cleans with the same warm soapy water as the slab, with the lock and hinge mechanisms benefiting from light annual lubrication.
Monthly cleaning routine
The core cleaning routine is the same one you would use on any quality painted surface, scaled to a front door.
Fill a clean bucket with warm water and a small amount of mild washing-up liquid. Standard supermarket washing-up liquid is fine. Use a soft microfibre cloth or a non-abrasive sponge. Wipe the door slab from top to bottom, working with the moulded grain rather than across it. Move on to the frame, the threshold and the door surround. Rinse with clean water on a fresh cloth and dry with a soft towel to prevent water marks.
Clean the glass separately with a standard glass cleaner, or a vinegar and water solution if you prefer a less chemical option. Use a clean microfibre cloth and a separate dry cloth for finishing. Avoid letting glass cleaner run down onto the GRP skin, where it can leave residue.
The hardware (handles, letterplate, knocker, spy hole) cleans with the same warm soapy water and a soft cloth. Avoid abrasive metal polishes on coated finishes such as anthracite, brushed chrome or matte black, because the polish can lift the coating over time. Brass hardware can be polished with a brass-specific polish if you want it to stay shiny, or left to develop a natural patina if that suits your taste.
How often is “monthly” actually necessary? In practice, a wipe-down every six to eight weeks is plenty for most homes. Coastal properties, busy family entrances and homes near roads with heavy pollution benefit from more frequent attention. Rural properties on quiet lanes can stretch to three months between cleans without consequence.
What not to use on a composite door
The list of products that cause damage is short but worth knowing. None of these belong on a composite door, regardless of what marketing copy elsewhere may claim.
Bleach and bleach-based cleaners can dull the GRP finish and leave permanent marks. Solvent cleaners (white spirit, acetone, paint thinners) can soften and damage the skin. Abrasive scourers, scouring pads and rough sponges scratch the finish, particularly on darker colours where the marks show clearly. Pressure washers force water past the seals and into the frame, and the impact can dislodge weather strips and damage glazing seals. Strong degreasers and industrial cleaners are formulated for surfaces composite skin was not designed to resist.
Polishes and waxes are a more nuanced area. Some manufacturers approve specific polishes for their products; others void warranties if anything other than warm soapy water is used. The honest advice is to check your door’s care guide before applying any polish or wax. If in doubt, leave the slab unpolished. A quality composite door does not need polish to maintain its appearance.
WD-40 deserves a separate mention because it is the lubricant homeowners reach for most often. It is not the right product for composite door locks. WD-40 is a water displacer rather than a lubricant, it attracts dust over time, and on most multipoint locks it can gum up the mechanism if used regularly. Silicone spray is the correct product for hinges and exposed mechanism parts. Graphite powder, or a manufacturer-approved dry lubricant, is the correct product for the lock cylinder itself.
Hardware maintenance: hinges, locks, handles, keeps and cylinders
The moving parts of a composite door benefit from a small amount of attention once a year. This is the maintenance step that pays back the most for the least time invested.
Hinges should be lubricated annually with a light spray of silicone spray. Open the door, spray a small amount on the hinge pin from above, and operate the door a few times to work the lubricant in. Wipe away any excess. The same applies to any visible moving parts of the multipoint lock, including the hooks, deadbolts and rollers, which engage with the frame when the door is locked.
The lock cylinder is the small barrel that the key turns. It needs different treatment. Spray lubricants and oils gum up cylinder mechanisms over time and attract dust into the keyway. The right product is graphite powder, applied sparingly into the keyway, or a manufacturer-approved dry lubricant. Insert the key, turn it a few times to work the graphite in, and you are done.
Handles can become loose over time as the fixings work slightly with daily use. A loose handle is usually fixed by tightening the small grub screws on the back of the handle plate, which most reputable manufacturers include as a serviceable feature. Do not over-tighten; finger-tight plus a quarter turn is generally enough.
Strike plates and keeps (the metal plates on the frame that the locking points engage with) should sit cleanly with the slab when locked. If the slab pulls tight against the seals when the lock throws, the strike plates are aligned correctly. If the slab feels loose or the lock has become stiff, the strike plates may need adjustment, which is usually an installer job rather than a homeowner task.
Seals, draughts and weatherproofing checks
The compression seals around the slab are what give a modern composite door its airtight closure. Check them visually each spring and autumn.
The seals should look clean, intact and continuous around the perimeter of the slab. They should compress slightly when the door is closed and recover their shape when the door is opened. Damaged, hardened, torn or compressed-flat seals no longer seal effectively.
The simple test is the paper test. Close a sheet of paper in the door at various points around its perimeter and try to pull it out. If the paper holds firmly, the seal is compressing properly. If the paper slides freely, the seal at that point is no longer doing its job. Repeat at the threshold, the hinge side, and the lock side.
A failed seal section can usually be replaced individually without replacing the whole door. The seal sections push into a channel in the frame and are inexpensive parts; an installer can usually fit replacements in under an hour.
The threshold is the bottom of the door and the place where draughts most often persist. Check the threshold sweep (the brush or rubber strip on the underside of the slab) for wear, and clear any debris from the drainage channels in the threshold profile. Blocked drainage channels allow water to back up against the door, which accelerates wear on the bottom seal and can lead to minor water ingress over time.
Preventing fading, stains and scratches
Modern composite doors are engineered to resist UV fading better than almost any other front door material on the market, but no finish is completely fade-proof under decades of British sun.
South-facing and west-facing doors take more UV exposure than north-facing doors, and dark colours show fade more visibly than light ones. A black or anthracite door on a south-facing elevation may look slightly less saturated after fifteen years than the same door on a north-facing elevation. The change is usually subtle and uniform, which is why it goes largely unnoticed.
The best protection against fading is regular cleaning. Dirt and pollution sit on the surface of the GRP skin and accelerate UV degradation. A clean door fades more slowly than a dirty one. There is no need for UV protectant sprays or polishes for most properties; the GRP skin already includes UV stabilisers as part of its construction.
Stains from organic matter (bird droppings, leaf debris, tree sap) should be cleaned promptly because they can etch into the skin if left for weeks. Warm soapy water removes most marks if dealt with within a day or two.
Scratches on composite doors are uncommon because the GRP skin is genuinely tough, but they do happen. Light surface scratches can sometimes be polished out with a manufacturer-approved touch-up product. Deeper scratches that have penetrated the colour layer are harder to repair invisibly. Some manufacturers offer touch-up pens in matching colours for minor damage. For visible scratches on the front face of the door, professional repair or skin replacement is occasionally the only route to an invisible fix.
Seasonal maintenance: winter, summer, coastal and urban homes
The maintenance routine adjusts slightly with the seasons and the location of the property.
Winter is the season the door earns its keep. Compression seals work hardest in cold, wet weather, and a properly closed and locked door should essentially eliminate draughts. After heavy storms, check that water has not pooled at the threshold and that drainage channels are clear. Salt or grit thrown from gritted pavements can find its way onto the door slab; rinse it off promptly with clean water rather than letting it sit.
Summer brings UV exposure and thermal expansion. Dark-coloured composite doors can warm noticeably in direct sun, and minor seasonal expansion is normal. If the door starts to feel slightly tighter against the frame in hot weather, this is usually a temperature effect rather than a fault, and the door will return to normal as the weather cools. Persistent tightness across seasons suggests hinge adjustment may be needed.
Coastal homes face salt-laden air, which accelerates corrosion on hardware and can leave deposits on the slab. Rinse the door with clean water more often than you would inland, ideally every couple of weeks. Stainless steel hardware should be specified on coastal installations from the outset, and any signs of corrosion on hardware should be addressed quickly with a rinse and a light buff with a soft cloth.
Urban homes face pollution and fine particulates from traffic. The slab and glass collect a film of grime more quickly than rural properties, and monthly cleaning is genuinely useful rather than optional. Pay particular attention to the glass and the upper part of the slab where airborne deposits settle.
Troubleshooting: common problems and what they mean
A handful of issues come up regularly on otherwise sound composite doors. Most have simple causes.
The door is sticking or scraping
Usually the slab has dropped slightly on its hinges, or seasonal expansion has tightened the fit. Most modern multipoint locks include a hinge adjustment that allows the slab to be lifted slightly back into alignment. A locksmith or your installer can usually correct this in under an hour. If the slab itself has warped, which is rare on quality composite doors, the slab is the problem and adjustment will not solve it.
The lock is hard to lift or throw
Usually because the slab has dropped and the locking points are no longer engaging cleanly with the strike plates. Lubrication may help in the short term, but the underlying cause is alignment. Repeatedly forcing a stiff lock can damage the mechanism, so address the alignment rather than working around it.
Draughts around the frame
Usually compression seal failure or seal compression after years of use. The paper test identifies which sections need replacement. Individual seal sections are inexpensive and quick to replace.
Condensation on the inside of the glazing
If condensation forms on the inside surface of the glazed unit, the room is humid and the glass is colder than the dew point of the air. This is a ventilation issue, not a door issue. If condensation forms between the panes of the double-glazed unit (cloudy or misted glass that does not wipe clear), the unit’s seals have failed and the unit needs replacement. Failed glazing units are usually replaceable individually.
Loose handle
The fixing screws on the back of the handle have loosened with use. Tighten the grub screws gently. If the handle still feels loose after tightening, the spindle or the handle itself may have worn and need replacement.
Faded or scratched finish
Light fading is a UV effect on south-facing doors over many years and is generally not repairable. Stains from organic matter usually clean off with warm soapy water if addressed promptly. Scratches range from polishable to professional-repair-only depending on depth.
Water ingress at the threshold
Usually blocked drainage channels in the threshold profile or a worn threshold sweep. Clear the channels with a soft brush and inspect the sweep for wear. Persistent water ingress after these checks suggests an installation issue and should be referred to your installer.
When to call an installer
Most composite door maintenance is genuinely homeowner-level work. A few situations call for an installer or a competent locksmith rather than a cloth and a screwdriver.
Lock mechanism failure where the multipoint lock no longer engages cleanly, or where a key has snapped in the cylinder, needs professional attention. Forcing a failing lock typically makes the problem worse and risks damage to the door slab or frame.
Persistent alignment issues that have not resolved with hinge adjustment may indicate frame movement or a more significant fault. An installer’s diagnosis is more efficient than guesswork at this stage.
Seal damage that runs around significant lengths of the perimeter is a job for someone with the correct profile and the right tools. Individual short sections can be a homeowner repair on a confident DIY job; whole-perimeter replacement is typically professional work.
Glazing unit failure (cloudy or misted units that no longer clear) needs a glazier or your original installer. The unit is replaced as a sealed cassette rather than repaired in place.
Visible damage to the slab itself (deep scratches, cracking, swelling at the base, separation between the skin and the frame) should be assessed by the original installer under warranty wherever possible. Most reputable manufacturers offer warranties of ten years or longer on composite doors, and significant slab faults typically fall within their scope.
Most reputable installers offer a free service call in the first year to fine-tune adjustments as the door beds in. Take advantage of this; it is genuinely useful and rarely added to in subsequent years.
Warranty, building regulations and replacement-door paperwork
Maintenance is not just about appearance and operation. It also affects the documentation that protects you when you sell.
Most composite door manufacturers offer warranties of ten years or longer on the slab, with separate (often shorter) warranties on the hardware and glazing units. The warranty terms typically specify what cleaning and maintenance products are acceptable. Using bleach, solvents or unapproved polishes can technically void parts of the warranty, even if no damage is visible. The honest framing is to stick to warm soapy water, microfibre cloths and silicone or graphite lubricants, and you will not stray from any reputable manufacturer’s care guide.
Replacement external doors fall under Approved Document L of the Building Regulations, which sets a minimum thermal performance for any door fitted as part of a replacement. Your installer should have provided a FENSA or CERTASS certificate confirming building regulations compliance, usually within four to six weeks of installation. Keep this certificate with your home documentation. Conveyancers ask for it when you sell the property, and without it, buyers can demand a retrospective Building Control inspection.
If the door has been damaged or modified in a way that affects the original certification (for example, the cylinder has been replaced with a non-rated unit, or the glazing has been replaced with non-compliant glass), this is worth knowing about because it can affect resale. In practice, sensible homeowner maintenance never crosses these thresholds, but invasive repairs by unregistered contractors can.
Maintenance checklist
The full year of composite door maintenance fits comfortably onto a single page. Here it is.
Every six to eight weeks: wipe the slab, frame, threshold, handles and letterplate with warm soapy water and a microfibre cloth. Clean the glass separately with glass cleaner. Dry with a soft towel.
Every six months (spring and autumn): visually check the compression seals around the perimeter and at the threshold. Run the paper test if the door has felt different recently. Clear the threshold drainage channels. Check that the lock throws cleanly and the door pulls tight against the seals when locked.
Annually: lubricate the hinges with a light silicone spray. Apply graphite powder or a manufacturer-approved dry lubricant to the lock cylinder. Tighten any loose handle fixings. Inspect the slab and frame for visible damage.
After storms or coastal exposure: rinse the slab with clean water to remove salt and debris. Check that no seals have lifted or torn.
If anything feels persistently wrong (sticking door, stiff lock, draughts that have not improved with seal checks): call the installer rather than working around it.
This routine, applied across the years, keeps a quality composite door looking and working close to factory condition for the full 25 to 30 year service life of the product.
Frequently asked questions
1. How often should I clean a composite door?
Every six to eight weeks for most homes, more frequently for coastal or urban properties exposed to salt or pollution, less frequently for rural homes on quiet lanes. The slab tells you what it needs; visible dirt or film is the signal to clean.
2. Can I use washing-up liquid on a composite door?
Yes. Mild washing-up liquid in warm water is the recommended cleaning solution for composite doors. Use a microfibre cloth or non-abrasive sponge, and rinse and dry with a soft towel to prevent water marks.
3. Can I use bleach or abrasive cleaner?
No. Bleach can dull the GRP finish and leave permanent marks. Abrasive cleaners and scourers scratch the skin, particularly on darker colours. Avoid both, even on stubborn marks; warm soapy water and a little patience usually resolve the issue.
4. Can I pressure wash a composite door?
No. Pressure washers force water past the seals and into the frame, can dislodge weather strips and damage glazing seals. The correct method is a clean cloth, warm soapy water and gentle pressure.
5. Should I use WD-40 on composite door locks?
No. WD-40 is a water displacer rather than a true lubricant, attracts dust over time, and can gum up multipoint lock mechanisms with regular use. Use silicone spray for hinges and exposed mechanism parts, and graphite powder or a manufacturer-approved dry lubricant for the cylinder.
6. Why is my composite door hard to lock?
Usually because the slab has dropped slightly on its hinges and the locking points are no longer engaging cleanly with the strike plates. Hinge adjustment, available on most modern multipoint locks, resolves this. Forcing a stiff lock typically makes the problem worse.
7. How do I stop my composite door fading?
Regular cleaning is the best protection. Dirt and pollution accelerate UV degradation, so a clean door fades more slowly than a dirty one. South-facing doors fade more visibly than north-facing ones; this is normal and the change is usually subtle over many years. UV protectant sprays are generally not necessary on quality composite doors.
8. Can scratches be repaired?
Light surface scratches sometimes polish out with a manufacturer-approved touch-up product. Deeper scratches that have penetrated the colour layer are harder to repair invisibly. Some manufacturers offer matched touch-up pens for minor damage; significant scratches on the front face usually need professional attention.
9. Can I repaint a composite door?
Specialist primers and exterior paints exist that will adhere to GRP, but the result is rarely as durable or attractive as the original factory finish, and repainting can affect the warranty. The honest framing is that composite doors are designed not to be repainted. If you genuinely need a different colour, replacement is usually the better long-term answer.
10. Why is there condensation on the glass?
Condensation on the inside surface of the glass usually indicates that the room is humid and the glass is colder than the dew point of the air. This is a ventilation issue rather than a door fault. Condensation between the panes (cloudy or misted glass that does not wipe clear) means the glazing unit’s seals have failed and the unit needs replacement.
11. How do I know if the seals need replacing?
Run the paper test. Close a sheet of paper in the door at various points around the perimeter and try to pull it out. If it slides freely, the seal at that point is no longer compressing. Visible damage, hardening, tearing or permanent compression of the seal also indicate replacement is due.
12. When should I call an installer?
For lock mechanism failure, persistent alignment issues, significant seal damage, glazing unit failure, or visible damage to the slab itself. Most reputable installers offer a free service call in the first year, which is worth using for any minor adjustments needed as the door beds in.
13. Does poor maintenance affect the warranty?
It can. Most warranties specify acceptable cleaning and maintenance products, and using bleach, solvents or unapproved polishes can technically void parts of the warranty. Sticking to warm soapy water, microfibre cloths and silicone or graphite lubricants keeps you safely within any reputable manufacturer’s care guide.
14. Do replacement composite doors need to meet UK Building Regulations?
Yes. Replacement external doors are controlled fittings under the Building Regulations and must meet thermal performance, safety glazing and other technical standards. A registered FENSA or CERTASS installer handles certification on your behalf and provides a certificate confirming compliance. Keep this with your home documentation; conveyancers ask for it when you sell.