Greater London · England
Window Mastic in Kensington
Mastic around window and door frames, sills and patio doors for homes and businesses in Kensington and across Greater London. Fully insured, ARBOMaster approved and guaranteed for a year.
- Draughts coming in around windows and doors
- Leaking joints at the ends of sills
- Untidy mastic left by window fitters
Common questions in Kensington
I let a flat near Kensington Olympia station. Can you help?
Yes. We work for landlords and agents as well as householders. Just phone 0345 464 0079 or send us an email with the address and what needs doing, and we will send you a clear quote.
Do you cover Kensington for window mastic?
Yes. Our work covers London and the South East, and Kensington is part of that. You can ring 0345 464 0079 or send us an email and tell us what needs doing, and we will give you a clear price.
How many windows can you do in a day?
It depends on access, the old mastic and the size of the frames. You will know the timing when we quote.
Do you work on first-floor windows?
Yes, where they can be reached safely. Tell us about access when you get in touch and we’ll plan for it.
Is it OK to seal over old sealant?
No. Fresh sealant does not stick to old sealant, and it traps any mould or water underneath. It all has to come out first.
Can you quote for more than one area?
Yes. More than one area can go on one quote.
Will resealing my frames help with draughts?
It will if the frame joint is the problem. We check where the draught is before any work starts.
Do I need to be at home?
Access is agreed with you when the job is booked. For inside work, that normally means someone being in.
How we handle window mastic in Kensington
Behind a thin line of old mastic there’s sometimes a deep void. Filling it with sealant alone leaves a joint that can’t move properly, so we fit backing rod to set the right depth. That way the new bead bonds to the frame and the wall only. Typical jobs include cracked or shrunken mastic around the frame and gaps between the frame and the inside reveal, on composite doors, uPVC windows and patio & French doors.
Much of London’s older housing was built with timber sash windows, some still in place and some long since replaced. Either way, the mastic between frame and brickwork is what stops draughts and rain getting in, in Kensington as anywhere.
We guarantee the work for a year. If something isn’t right with it in that time, tell us and we’ll put it right.
- Where
- Kensington (W11, W8, W14, SW7)
- Wider area
- Greater London
- Cover
- 12 months on all our work
- Price
- A clear price before any work starts
- Call
- 0345 464 0079
- Updated
- 26 October 2026
Places near Kensington
What else we do in Kensington
Keeping the joints in good condition
Simple care keeps the joints in good condition. Our advice:
- Walk round the house once a year and look at the joints
- Clear any debris from frame drain holes
- Keep timber frames painted
- Keep jet washers away from the mastic
Try not to touch the new joint while it cures, following the cure time we give you. Keep jet washers away from the frames.
Look out for the warning signs: split or missing mastic, gaps, damp patches inside or black mould on the reveal. If you notice one, it’s time to get the joint looked at.
DIY versus a professional finish
Overfilling a joint is a classic DIY mistake. A thick, smeared bead looks untidy and doesn’t move well, and the joint depth matters as much as the finish.
What a professional job adds is preparation and the right product. Joints are cleaned back to sound surfaces and dried, and the sealant is matched to the joint and its conditions.
Signs you need window mastic in Kensington
Water runs down the glass onto the sill, and the ends of the sill, where it meets the wall, are where it gets in. When that sealant fails, water gets into the wall or under the frame.
The problems people normally mention when they call include:
- A bead that does not match the frame
- Gaps left after new windows were fitted
- Draughty joints inside around the window
- Whistling draughts around closed windows
For landlords with property near Kensington Olympia station, cracked frame mastic tends to show up as a draught or damp complaint, so it’s worth checking between lets.
Questions to ask before booking
- The length of the guarantee
- How the surfaces are prepared before sealing
- Whether they seal over old material or remove it
- What happens if the job turns out different
Why deal with it now?
Draughts and leaks do not always mean new windows. If the frames and glass are in good order, resealing the joints is often all that’s needed. Problems with the glass or gaskets are for a window company, and we’ll say so. In a flat in Kensington, failed sealant seldom stays inside your own four walls: water can reach the neighbours below, and gaps in fire-rated joints affect the whole building.
Commercial jobs are quoted on the same basis as homes: the amount of work, the access and the products needed, along with when we can work on site. Call for a quick quote and we’ll explain what it covers.
Why Kensington customers choose us
- Colour picked to suit the job
- Experience in homes, commercial sites and hotels
- Fully insured
- Old sealant always removed completely
Read our cost guide or what customers say.
What we cannot put right
In fairness, there are a few things sealant will not fix:
- A sash or casement that will not close properly
- A failed sealed unit that has misted up
- Damp problems in the wall away from the window
If you’re not sure, just phone 0345 464 0079 or drop us an email and we will give you a straight answer.
Joints and surfaces we work on
- Timber windows & doors
- Composite doors
- Patio & French doors
- Aluminium frames
- Window sills
- uPVC windows
How the visit works
We bring everything the job needs with us, so there’s nothing for you to buy. Once we have agreed what’s being done, we protect the area and start. It normally takes a few hours for a few frames, or a day or more for a whole house. In 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.
- We check how each frame can be reached safely.
- Old, cracked mastic is removed completely.
- The surfaces are cleaned and left dry, and primed where the sealant calls for it.
- Deep voids are backed, then the sealant is gunned in.
- The joint is shaped to shed water and the area tidied.
How to prepare
- Mention any leaks or damp you’ve noticed
- Let us know about parking restrictions
- On commercial sites, let us know about site rules
Ask for a quote
For a quick quote, get us on the phone, or email us if that’s easier. Describe what needs sealing and we’ll explain what’s involved.
Related advice
Landlords, agents and businesses in Kensington
Businesses can book us for washrooms, kitchens, offices and more. On commercial sites, working times can be discussed when we quote.
Landlords and letting agents in Kensington can book us as well as homeowners. Sealant work between tenants keeps a property looking cared for.
Kensington homes and the weather
In London conversions and blocks, the lease decides who is responsible for the frames, so it’s worth checking before booking. Compared with the north and west, the South East gets less rain, yet outdoor joints still have to be sealed dry, so jobs are booked with the weather in mind.
For an older house near a landmark such as Church of St Barnabas, the joint between an old wall and a newer frame is normally the first place rain gets in. For site and facilities teams at buildings such as St Barnabas and St Philip's CofE Primary School, its window and door frames need their mastic kept sound, just like a home’s.
Kensington is about 5 miles west of London, in Greater London. We carry out window mastic for homes and businesses in Kensington. Across Greater London, we cover 764 places, Kensington among them.
Work in W11, W8, W14 and SW7 works the same way as everywhere else we cover. We cover properties on Kensington High Street, Edwardes Square and Somerset Square. Kensington sits on or near the A402 and B316, so getting to you is simple. Nearby, we also carry out window mastic in Holland Park (1 mile north), Notting Hill (1 mile north), Shepherd's Bush (1 mile west), Notting Dale (1 mile north) and White City (1 mile north-west). Larger places within reach include London (5 miles east), Marylebone (3 miles north-east), St Pancras (4 miles north-east), Shoreditch (6 miles east), Walthamstow (10 miles north-east) and Hoxton (6 miles north-east). Kensington is among the bigger towns we cover in Greater London.
What’s near Kensington
In Kensington, that means homes and buildings near Holland Park, Scarsdale Tavern and Holland Park School. You’ll also find Kensington School (0.5 miles east) and Abdus Salam Library (1 mile east). Kensington has its own railway station: Kensington Olympia station. A little further out are Kensington Arcade (within half a mile east) and London Museum (0.7 miles north-east). For a walk, there’s WWT London Wetland Centre and The Long Water.