Maintaining your Windows

Looking after your windows and doors will help maximise their life and performance, and enables you to maintain product warranties.

Preventing damage

If your new house or renovation is under construction, check that your builder protects the joinery at all stages during the building process. It’s much easier – and far more cost-effective – to avoid damage than to try to repair it. Inspect the windows and doors on delivery for any damage before they are accepted. And see that windows and doors are installed soon after delivery to site, as they are more likely to get accidentally damaged when stored for extended periods.


Once installed, your builder must mask the inside and outside of each window and door with masking tape and tough polythene film to protect the frame and glass from damage for the rest of the construction period. Apart from the physical damage from other building materials, major damage can also be caused, to aluminium frames in particular, by concrete and mortar used in brickwork or plaster cladding.

Handle with gloves at all times

Ask your builder to use disposable gloves when handling your windows and doors to help protect the surface from any substances on their hands, such as sunscreen, sealants, paints, oils and solvents. Most good builders know to do this.

Washing and general care

To maintain their performance and looks, all window and door units (whether timber, aluminium or uPVC) benefit from a regular washdown. Wash them all over, not just the parts that are sheltered from the rain. In fact, looking after your windows is very much like looking after a new car – a regular wash keeps your investment in smart condition.

Avoid harsh chemicals

The general principle is to avoid caustic or volatile chemicals (which can damage surfaces) and harsh abrasives, which can leave scratches. These extremes shouldn’t be necessary so long as you wash often and use a gentle soap solution.


Dry glass off with a window squeegee and soft, dry cloth if you want to avoid any smears. And be very observant while cleaning, as micro grit trapped in cleaning cloths can cause scratches.


Depending on your framing materials, maintenance may also involve lubrication and adjustment of moving parts, or small repairs, some requiring professional assistance.

Timber frames

Timber is an excellent framing material that can perform well for decades, so long as you look after it. Water is its greatest enemy, either from rainfall or airborne interior/exterior vapour. Neglected timber can become prone to mould and rot, leading to structural damage, loose panes and thermal inefficiency. In any case, timber is naturally prone to shrinking and expanding depending on humidity and temperature, and this movement will affect paint finish, mechanical fit and performance.

Repair and maintenance

To avert costly and complex repair work, a regimen of regular checking and maintenance is critical. We recommend doing this every six months – or more often if you live in a coastal area or a particularly humid climate. 

Sponge down exteriors of windows and frames with a pH-neutral detergent in warm water. This helps remove dust and bacteria, inhibiting mould or mildew; clean, smooth timber surfaces are also better at shedding any pooled water. Wash the window panes first, then the frames, then rinse with clean water. If there is mould, applying a solution of one part distilled white vinegar to four parts water, then wiping it off, may shift it. Clean the interiors of frames with a soft, dry cloth.

Check frame exteriors for chips, splits or gaps. Repair any such damage with wood filler, then sand it flat and paint it over. Check frames carefully for flaking or cracking paint, and repaint when necessary. This may require sanding and a base coat/topcoat, depending on the state of things. It may also mean taking out sashes or casements so as to avoid gumming up their movement. With varnished frames, polyurethane-based varnishes have a habit of delaminating after a year or two, needing renewal.

When repainting timber frames, your choice of carrier (oil, water, etc.) will depend on the timber; if in doubt, consult your local paint supplier.

Check putty for looseness or cracking, and have it replaced if necessary. Allow fresh putty to skin over (a couple of weeks should do, but no longer than a month), then apply an enamel undercoat, ensuring the paint overlaps the glass. Then add topcoat. Some glaziers now use adhesive strip to bed panes into frames, then add timber beading in place of putty; this beading will require painting.

Check the action of hinges, locks and stays, easing where necessary with a little light machine oil or a silicone-based spray lubricant. 

Keep an eye out for borer, particularly in the untreated timbers of older homes. You won’t see the insects, but they leave conspicuous tiny holes as they exit timber. Infested wood can be treated; there are also products that will deter borer. Keeping timber dry will help keep the insects out, as they like moist wood.

On top of your six-monthly maintenance, schedule a regular full refinish: every three to four years for painted frames, or one to two years for varnished or stained frames. Fully sand down each frame before applying the finish of your choice. Check the mechanisms of sash windows, replacing cords if they are rotten.

Aluminium frames

For aluminium frames, a washdown every three months is normally sufficient, but you will need to wash them more frequently if you live near the seaside, a building site or an industrial area. A build-up of damaging substances like sea salt, lime or other chemicals can damage the surface finish.

Repair and maintenance

To wash aluminium windows and doors, use a good-quality, soft-bristled brush and a dilute solution of mild, pH-neutral liquid dishwashing detergent. Some brushes have in-built detergent dispensers and connect directly to the garden tap. These brushes make it easy to rinse off the detergent bubbles, which is an important part of the care process.

For anodised aluminium, more difficult grime deposits may require the use of a mild abrasive such as pumice powder and water. And if you find a greasy deposit, cleaning may require a soft cloth dipped in white spirits. It’s important to thoroughly rinse the windows and doors after cleaning to fully any spirit residues. We do not recommend you use solvents or pumice on a powdercoated finish – just use a mild soap and soft cloth.

Never use emery paper, sandpaper, steel wool or other highly abrasive materials on any aluminium, nor acid or alkaline cleaners, or any chemical cleaners, as they can damage the anodised or powdercoated finish. Be careful with emulsion cleaners, as they, too, can attack anodised coatings.

If you hire a commercial cleaning company, ensure they provide you with written assurances that they will only use products safe for aluminium joinery and glass. If they don’t provide a written assurance, do not use their services. Damage to windows and glass (and other parts of buildings) caused by cleaning products can result in difficult and costly repairs.

When painting near aluminium frames, cover and protect them with a drop sheet. In the event of accident, act quickly and remove splashes from windows and frames with a soft cloth soaked in water.

Care with sunscreen

Some sunscreens contain semi-conducting metal oxides, such as titanium dioxide or zinc oxide, which can damage protective finishes. They can accelerate the degradation of that surface up to 100 times faster than is normal, leaving behind the indelible images of the handprint. 

It is strongly recommended you wear gloves, when handling aluminium, to protect your windows and doors from sunscreen stains. In the event of accident, thoroughly wash down the affected area with soapy water and rinse it clean.

Polishing and recoating

When your powdercoated joinery starts to fade or grow dull, you can polish it. Most coatings will benefit from a light cutting automotive polish, but always test it in a concealed area first. Powder manufacturers also supply dab sticks and spray cans for touch-ups.

Occasionally, you may need to get your aluminium windows recoated. You can recolour your joinery without removing it from the building. We recommend that you seek an in-situ refinisher who is also member of the Association to ensure you get a quality result. For consistency, colour matching should be done in daylight, but not in direct sunlight.

uPVC frames

One of the plus points of uPVC is that it’s a durable and comparatively low-maintenance material. Since it is a plastic, however, there are some treatments that should be avoided as they may leave streaks or scarring. Also, because frames and hardware are technically complex assemblies, it’s far better to prevent damage than attempt repair, making regular maintenance a wise strategy.

Repair and maintenance

As with aluminium, a regular washdown will help keep your frames looking good, preserve their finish and, importantly, catch any mechanical issues before they lead to damage. Washing every three months should be sufficient unless you live by the coast or near a source of pollution, in which case two-monthly attention is recommended. 

Use warm water with a drop of detergent and apply with a soft white cloth. For stubborn dirt, apply the solution and leave for five minutes before giving it another wipe. Another option is to use a solution of one part white vinegar to four parts hot water. After washing, rinse down with clean water, then wipe dry with a soft microfibre cloth.

Do not use any of the following: cream cleaner, caustic solutions (such as ammonia), alcohol or cellulose thinners, bleach, white spirits or methylated spirits. Avoid scouring pads, wire wool, or anything else liable to scratch the uPVC. If you want to use glass cleaner on panes, apply it to a cloth and ensure it does not touch the frames; it would be safer to use a vinegar solution on glass and then squeegee it off.

Give the openings of your uPVC frames a regular clean. Open each window or door to the point of resistance (and no further) and, with a brush, or a brush fitting on a vacuum cleaner, sweep dust and dirt out of the channels. Use a damp cloth to wipe over the gaskets, which are prone to trapping dirt. Gaskets that become unseated (particularly in cold seasons) can sometimes be popped back in, but if they fail regularly or split, they will need replacing.

Annual lubrication, using petroleum jelly or a silicone-based spray lubricant, will help keeping moving parts working. Pay attention to lock and closure mechanisms. If, over time, a handle becomes hard to open or close, do not force it. First try lubricant; then if needs be, seek help from a professional, such as your local window installer, who can make any necessary adjustments to all your frame mechanisms. It is advised that you choose the professional route, rather than DIY, if your frames are still under warranty.