Greater London · England
Window Mastic in South Kensington
We cover South Kensington for mastic around window and door frames, sills and patio doors. Old sealant removed completely, joints prepared properly and every job guaranteed for a year.
- Leaking joints at the ends of sills
- Rain getting in at the frame or under the sill
- Black, perished sealant on frames
Window mastic in South Kensington: local notes
In London conversions and blocks, the lease decides who is responsible for the frames, so it’s worth checking before booking. With historic houses such as Carlyle's House (about 0.6 miles south-east) nearby, there’s older building stock in the area around South Kensington as well as newer homes. In older buildings, older frames set in brick or stone need a sealant that suits them, and sometimes that is traditional sand mastic.
If you let a flat or house near West Brompton station, renewing tired window mastic between tenants heads off draught and damp complaints. Managing a site like Our Lady of Victories RC Primary School? Then its window and door frames need their mastic kept sound, just like a home’s.
South Kensington is about 1 mile south-east of Kensington, in Greater London. Every kind of property in South Kensington is covered for window mastic, old or new, large or small. The work is guaranteed for a year. We cover 764 towns and villages across Greater London, large and small.
All of SW3, SW7 and SW10 is covered for window mastic. If you need window mastic at a property on King's Road, Fulham Road and Museum Lane or anywhere close by, we can help. You’ll find South Kensington on the A3217, which makes it straightforward to reach with everything needed for window mastic. Neighbouring places we cover for window mastic include Little Chelsea (1 mile south), Chelsea (1 mile east), Brompton (1 mile north-east), World's End (1 mile south) and Earl's Court (1 mile west). Within a short drive, we also cover London (4 miles east), St Pancras (4 miles north-east), Shoreditch (5 miles north-east), Walthamstow (9 miles north-east), Hoxton (5 miles north-east) and Whitechapel (5 miles east).
Near you in South Kensington
We work in homes and buildings around London School of Dramatic Art, Burton’s Court and Anglesea Arms. You’ll also find Natural History Museum Library and Archives (within half a mile north) and Collingham College (0.5 miles west). The nearest railway station is West Brompton station, roughly 0.8 miles west of the centre. Nearby you will also find Victoria and Albert Museum Spiral (under half a mile north) and Baynard's Castle (3.6 miles north-east). For a walk, there’s Serpentine and Campden Hill.
How we handle window mastic in South Kensington
There are two joints on most windows. Outside, the mastic keeps rain out; the internal joint closes the gap to the plaster and stops draughts. We seal one or both, depending on what’s needed. We work on timber windows & doors, composite doors and uPVC windows, and the jobs we see most are white mastic on grey or black frames and cracked sealant at the sill ends.
London homes have every kind of window, from timber sashes in period terraces to aluminium and uPVC in newer blocks. The mastic around them dries out and cracks with age, letting in draughts and water.
Whatever the size of the job, you get the same one-year guarantee.
- Place
- South Kensington (SW3, SW7, SW10)
- Region
- Greater London
- Cover
- One year on every job
- Quote
- A clear price before any work starts
- Phone
- 0345 464 0079
- Page updated
- 26 October 2026
When it isn’t the sealant
It helps to know what we cannot do too:
- Soft or decayed wood in the frame
- Condensation trapped between the panes
- Draughts through the window seals rather than the frame
If in doubt, phone 0345 464 0079 or drop us an email and we’ll say what we think before booking.
Where we work in South Kensington
- Aluminium frames
- Composite doors
- Patio & French doors
- Window sills
- uPVC windows
- Timber windows & doors
How it works
On the day, there’s very little for you to do. Show us the job and we’ll take it from there. The work itself takes a morning for a couple of windows and a door, including the tidy-up. In South Kensington, as in most of London, parking needs a little planning. It helps if you can point us to a visitor permit or a bay close to the door.
- First, we go round the frames with you and agree the list.
- The old mastic is cut out and scraped back to clean surfaces.
- Deep gaps get closed-cell backing rod to set the depth.
- A flexible exterior sealant is applied in a colour to suit the frame.
- We tool each bead neatly and check every joint is closed.
Preparing for the visit
- Mention if the joints have been sealed before
- Keep children and pets away from the work area
- Try not to wet indoor joints just before the visit
Getting a quote
Quotes start with a quick conversation. Describe the problem, the location and the size of the job, and we’ll talk you through what we’d do. When it suits you, ring 0345 464 0079 or drop us an email.
Advice
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Why deal with it now?
Redecorating is a good moment to renew the mastic. A clean new bead makes new paint or render look finished, and it’s easier while the walls are being worked on anyway. In a London flat, a failed joint rarely stays your problem alone: water from a shower or window joint can reach the flat below, and gaps in fire-stopping matter to everyone in the building.
What you pay reflects the work, not guesswork. That is why we ask a few questions first.
What you get with us
- Colour agreed with you before we start
- White, clear, grey or coloured to suit, where the product allows
- More than 20 years in sealant work
- Anti-fungal sanitary silicone in wet areas
See what affects the cost and customer reviews.
DIY versus a professional finish
The biggest DIY mistake is sealing over old sealant. New silicone will not bond to old, so it peels away and traps moisture behind it. All the old material has to come out first.
The difference is mostly in the preparation and the product. We take joints back to clean, dry surfaces, and the sealant is matched to the joint and its conditions, and the work is guaranteed for a year.
Surface by surface
Aluminium frames
Aluminium moves with heat, and the frames are often slimmer than uPVC. A neat, narrow bead in a colour to match suits the frame.
uPVC windows
Fitters’ mastic on plastic frames is sometimes thin and rushed. We cut it out, back any deep gaps and reseal properly.
When to call us in South Kensington
On timber frames, paint and putty build up around the joint. Old mastic gets painted over and cracks under the paint, and the wood moves with damp as well as heat.
Common reasons people contact us are:
- Sealant in the wrong colour for the frame
- Cracked or shrunken mastic around the frame
- Draughts coming in around windows and doors
- Untidy mastic left by window fitters
South Kensington is in London, so parking needs planning: let us know about parking bays, permits or a driveway.
Before booking anyone
- How hidden problems are handled
- Who turns up on the day
- Whether you can choose the colour
- Whether the sealant suits the joint
Common questions in South Kensington
Is parking an issue for window mastic in South Kensington?
In much of London, parking needs planning: a visitor permit or a nearby bay makes the day run more smoothly, so mention what’s available when you book.
Do you work for landlords with property near West Brompton station?
Yes, we work for letting agents and landlords. Just phone 0345 464 0079 or email us and tell us about the property, and we will send you a clear quote.
How long will my window job take?
Allow a few hours for a few frames, or a day or more for a whole house. Access and how stubborn the old mastic is affect the time most.
Is it messy?
No. We protect the surfaces around the joints, and we clear up the old sealant and our materials before we leave.
Can I do it myself?
Sometimes. The key is preparation: remove all the old material and work on a clean, dry joint. We can always put it right if it fails.
Can I paint over the new sealant?
That depends on the product. Silicone isn’t paintable, but some hybrid sealants are. Tell us if you’re decorating and we will choose accordingly.
What should I tell you?
Only a few details: the address or postcode, what’s wrong and any access issues. Then phone 0345 464 0079 or send us an email.
Can you quote for more than one area?
Yes. Just list everything you need and we’ll quote it together.
How to look after the new joints
Simple care keeps the joints in good condition. We recommend:
- Air rooms to keep condensation down around windows
- Repaint timber before it’s bare
- Don’t use solvent cleaners on the joint
- Do not aim a pressure washer at the joints
On timber frames, keep the paintwork in good order, because bare, wet timber moves more and pulls at the joint. Keep paint off the silicone itself.
A failed joint lets water into the wall a little at a time. Often the first sign is a damp patch inside or flaking paint on the reveal. Catching it early keeps the fix to a reseal.